Publications

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2017

  • [DOI] Hong, Jiewei, Robert J. Hamers, Joel A. Pedersen, and Qiang Cui. A Hybrid Molecular Dynamics/Multi Conformer Continuum Electrostatics (MD/MCCE) Approach for the Determination of Surface Charge of Nanomaterials. The Journal of Physical Chemistry C 2017, 121, 3584–-3596.
    [Bibtex]
    @Article{hong2017hybrid,
    author = {Hong, Jiewei and Hamers, Robert J and Pedersen, Joel A and Cui, Qiang},
    title = {A Hybrid Molecular Dynamics/Multi Conformer Continuum Electrostatics (MD/MCCE) Approach for the Determination of Surface Charge of Nanomaterials},
    journal = {The Journal of Physical Chemistry C},
    year = {2017},
    volume = {121},
    pages = {3584–-3596},
    abstract = {The surface charge of nanomaterials determines their stability in solution and interaction with other molecules and surfaces, yet experimental determination of surface charge of complex nanomaterials is not straightforward. We propose a hybrid approach that iteratively integrates explicit solvent molecular dynamics simulations and a multiconformer continuum electrostatic model (MCCE) to efficiently sample the configurational and titration spaces of surface ligands of nanomaterials. Test calculations of model systems indicate that the iterative approach converges rapidly even for systems that contain hundreds of titratable sites, making the approach complementary to more elaborate methods such as explicit solvent-based constant-pH molecular dynamics. The hybrid method is applied to analyze the pKa distribution of alkylamines attached to a carbon-based nanoparticle as a function of ligand density, nanoparticle surface curvature, and ligand heterogeneity. The results indicate that functionalization strategies can modulate the pKa of surface ligands and therefore charge properties of nanomaterials (e.g., surface charge, charge capacitance). The hybrid computational approach makes a major step toward guiding the design of nanomaterials with desired charge properties.},
    doi = {10.1021/acs.jpcc.6b11537},
    publisher = {American Chemical Society},
    }
  • [DOI] Qiu, Tian A., Thu Ha Thi Nguyen, Natalie V. Hudson-Smith, Peter L. Clement, Dona-Carla Forester, Hilena Frew, Mimi N. Hang, Catherine J. Murphy, Robert J. Hamers, Vivian Z. Feng, and Christy L. Haynes. Growth-Based Bacterial Viability Assay for Interference-Free and High-Throughput Toxicity Screening of Nanomaterials. Analytical Chemistry 2017, 89, 2057-2064.
    [Bibtex]
    @Article{Qiu_2017,
    author = {Tian A. Qiu and Thu Ha Thi Nguyen and Natalie V. Hudson-Smith and Peter L. Clement and Dona-Carla Forester and Hilena Frew and Mimi N. Hang and Catherine J. Murphy and Robert J. Hamers and Z. Vivian Feng and Christy L. Haynes},
    title = {Growth-Based Bacterial Viability Assay for Interference-Free and High-Throughput Toxicity Screening of Nanomaterials},
    journal = {Analytical Chemistry},
    year = {2017},
    volume = {89},
    number = {3},
    pages = {2057--2064},
    month = jan,
    abstract = {Current high-throughput approaches evaluating toxicity of chemical agents toward bacteria typically rely on optical assays, such as luminescence and absorbance, to probe the viability of the bacteria. However, when applied to toxicity induced by nanomaterials, scattering and absorbance from the nanomaterials act as interferences that complicate quantitative analysis. Herein, we describe a bacterial viability assay that is free of optical interference from nanomaterials and can be performed in a high-throughput format on 96-well plates. In this assay, bacteria were exposed to various materials and then diluted by a large factor into fresh growth medium. The large dilution ensured minimal optical interference from the nanomaterial when reading optical density, and the residue left from the exposure mixture after dilution was confirmed not to impact the bacterial growth profile. The fractions of viable cells after exposure were allowed to grow in fresh medium to generate measurable growth curves. Bacterial viability was then quantitatively correlated to the delay of bacterial growth compared to a reference regarded as 100% viable cells; data analysis was inspired by that in quantitative polymerase chain reactions, where the delay in the amplification curve is correlated to the starting amount of the template nucleic acid. Fast and robust data analysis was achieved by developing computer algorithms carried out using R. This method was tested on four bacterial strains, including both Gram-negative and Gram-positive bacteria, showing great potential for application to all culturable bacterial strains. With the increasing diversity of engineered nanomaterials being considered for large-scale use, this high-throughput screening method will facilitate rapid screening of nanomaterial toxicity and thus inform the risk assessment of nanoparticles in a timely fashion.},
    doi = {10.1021/acs.analchem.6b04652},
    publisher = {American Chemical Society ({ACS})},
    }
  • [DOI] Gunsolus, Ian L., Mimi N. Hang, Natalie V. Hudson-Smith, Joseph T. Buchman, Joseph W. Bennett, Daniel Conroy, Sara E. Mason, Robert J. Hamers, and Christy L. Haynes. Influence of nickel manganese cobalt oxide nanoparticle composition on toxicity toward Shewanella oneidensis MR-1: redesigning for reduced biological impact. Environ. Sci.: Nano 2017, .
    [Bibtex]
    @Article{Gunsolus_2017,
    author = {Ian L. Gunsolus and Mimi N. Hang and Natalie V. Hudson-Smith and Joseph T. Buchman and Joseph W. Bennett and Daniel Conroy and Sara E. Mason and Robert J. Hamers and Christy L. Haynes},
    title = {Influence of nickel manganese cobalt oxide nanoparticle composition on toxicity toward Shewanella oneidensis {MR}-1: redesigning for reduced biological impact},
    journal = {Environ. Sci.: Nano},
    year = {2017},
    abstract = {Current high-throughput approaches evaluating toxicity of chemical agents toward bacteria typically rely on optical assays, such as luminescence and absorbance, to probe the viability of the bacteria. However, when applied to toxicity induced by nanomaterials, scattering and absorbance from the nanomaterials act as interferences that complicate quantitative analysis. Herein, we describe a bacterial viability assay that is free of optical interference from nanomaterials and can be performed in a high-throughput format on 96-well plates. In this assay, bacteria were exposed to various materials and then diluted by a large factor into fresh growth medium. The large dilution ensured minimal optical interference from the nanomaterial when reading optical density, and the residue left from the exposure mixture after dilution was confirmed not to impact the bacterial growth profile. The fractions of viable cells after exposure were allowed to grow in fresh medium to generate measurable growth curves. Bacterial viability was then quantitatively correlated to the delay of bacterial growth compared to a reference regarded as 100% viable cells; data analysis was inspired by that in quantitative polymerase chain reactions, where the delay in the amplification curve is correlated to the starting amount of the template nucleic acid. Fast and robust data analysis was achieved by developing computer algorithms carried out using R. This method was tested on four bacterial strains, including both Gram-negative and Gram-positive bacteria, showing great potential for application to all culturable bacterial strains. With the increasing diversity of engineered nanomaterials being considered for large-scale use, this high-throughput screening method will facilitate rapid screening of nanomaterial toxicity and thus inform the risk assessment of nanoparticles in a timely fashion.},
    doi = {10.1039/c6en00453a},
    publisher = {Royal Society of Chemistry ({RSC})},
    }
  • [DOI] Qiu, Tian A., Marco D. Torelli, Ariane M. Vartanian, Nathan B. Rackstraw, Joseph T. Buchman, Lisa M. Jacob, Catherine J. Murphy, Robert J. Hamers, and Christy L. Haynes. Quantification of Free Polyelectrolytes Present in Colloidal Suspension, Revealing a Source of Toxic Responses for Polyelectrolyte-Wrapped Gold Nanoparticles. Analytical Chemistry 2017, 89, 1823-1830.
    [Bibtex]
    @Article{Qiu2017,
    author = {Tian A. Qiu and Marco D. Torelli and Ariane M. Vartanian and Nathan B. Rackstraw and Joseph T. Buchman and Lisa M. Jacob and Catherine J. Murphy and Robert J. Hamers and Christy L. Haynes},
    title = {Quantification of Free Polyelectrolytes Present in Colloidal Suspension, Revealing a Source of Toxic Responses for Polyelectrolyte-Wrapped Gold Nanoparticles},
    journal = {Analytical Chemistry},
    year = {2017},
    volume = {89},
    number = {3},
    pages = {1823--1830},
    month = jan,
    abstract = {Polyelectrolyte (PE) wrapping of colloidal nanoparticles (NPs) is a standard method to control NP surface chemistry and charge. Because excess polyelectrolytes are usually employed in the surface modification process, it is critical to evaluate different purification strategies to obtain a clean final product and thus avoid ambiguities in the source of effects on biological systems. In this work, 4 nm diameter gold nanoparticles (AuNPs) were wrapped with 15 kDa poly(allylamine hydrochloride) (PAH), and three purification strategies were applied: (a) diafiltration or either (b) one round or (c) two rounds of centrifugation. The bacterial toxicity of each of these three PAH-AuNP samples was evaluated for the bacterium Shewanella oneidensis MR-1 and is quantitatively correlated with the amount of unbound PAH molecules in the AuNP suspensions, as judged by X-ray photoelectron spectroscopy, nuclear magnetic resonance experiments and quantification using fluorescent assay. Dialysis experiments show that, for a 15 kDa polyelectrolyte, a 50 kDa dialysis membrane is not sufficient to remove all PAH polymers. Together, these data showcase the importance of choosing a proper postsynthesis purification method for polyelectrolyte-wrapped NPs and reveal that apparent toxicity results may be due to unintended free wrapping agents such as polyelectrolytes.},
    doi = {10.1021/acs.analchem.6b04161},
    publisher = {American Chemical Society ({ACS})},
    }
  • [DOI] Hamers, Robert J.. Nanomaterials and Global Sustainability. Accounts of Chemical Research 2017, .
    [Bibtex]
    @Article{Hamers2017,
    author = {Robert J. Hamers},
    title = {Nanomaterials and Global Sustainability},
    journal = {Accounts of Chemical Research},
    year = {2017},
    doi = {10.1021/acs.accounts.6b00634},
    }
  • [DOI] Laskar, MR, DH Jackson, S. Xu, RJ Hamers, D. Morgan, and TF Kuech. Atomic Layer Deposited MgO: A Lower Overpotential Coating for Li [Ni0. 5Mn0. 3Co0. 2] O2 Cathode.. ACS applied materials & interfaces 2017, .
    [Bibtex]
    @Article{laskar2017atomic,
    author = {Laskar, MR and Jackson, DH and Xu, S and Hamers, RJ and Morgan, D and Kuech, TF},
    title = {Atomic Layer Deposited MgO: A Lower Overpotential Coating for Li [Ni0. 5Mn0. 3Co0. 2] O2 Cathode.},
    journal = {ACS applied materials \& interfaces},
    year = {2017},
    abstract = {An ultra-thin MgO coating was synthesized via atomic layer deposition (ALD) to improve the surface properties of the Li[Ni0.5Mn0.3Co0.2]O2 (NMC) cathode. An in-situ quartz crystal sensor was used to monitor the "self-limiting" surface reactions during ALD process and estimate the density of the deposited film. The electrochemical performance of the MgO-coated NMC cathode was evaluated in a half cell assembly and compared to other ALD-based coatings such as Al2O3 and ZrO2. Cyclic voltammetry studies suggest that ALD MgO has a higher Li-diffusion co-efficient which results in lower overpotential on the NMC cathode surface and improved Li-ion battery rate performance. MgO-coated NMC also yielded improved capacity retention over uncoated NMC in a long-range cycling test.},
    doi = {10.1021/acsami.6b16562},
    }
  • [DOI] Huang, Xu, Joseph William Bennett, Mimi N. Hang, Elizabeth D. Laudadio, Robert J. Hamers, and Sara E. Mason. Ab Initio Atomistic Thermodynamics Study of the (001) Surface of LiCoO2 in a Water Environment and Implications for Reactivity under Ambient Conditions. The Journal of Physical Chemistry C 2017, .
    [Bibtex]
    @Article{huang2017ab,
    author = {Huang, Xu and Bennett, Joseph William and Hang, Mimi N and Laudadio, Elizabeth D and Hamers, Robert J and Mason, Sara E},
    title = {Ab Initio Atomistic Thermodynamics Study of the (001) Surface of LiCoO2 in a Water Environment and Implications for Reactivity under Ambient Conditions},
    journal = {The Journal of Physical Chemistry C},
    year = {2017},
    doi = {10.1021/acs.jpcc.6b12163},
    publisher = {American Chemical Society},
    }
  • [DOI] Shearer, Melinda J., Leith Samad, Yi Zhang, Yuzhou Zhao, Alexander A. Puretzky, Kevin W. Eliceiri, John C. Wright, Robert J. Hamers, and Song Jin. Complex and Non-Centrosymmetric Stacking of Layered Metal Dichalcogenide Materials Created by Screw Dislocations. Journal of the American Chemical Society 2017, 139, 3496–-3504.
    [Bibtex]
    @Article{shearer2017complex,
    author = {Shearer, Melinda J and Samad, Leith and Zhang, Yi and Zhao, Yuzhou and Puretzky, Alexander A and Eliceiri, Kevin W and Wright, John C and Hamers, Robert J and Jin, Song},
    title = {Complex and Non-Centrosymmetric Stacking of Layered Metal Dichalcogenide Materials Created by Screw Dislocations},
    journal = {Journal of the American Chemical Society},
    year = {2017},
    volume = {139},
    number = {9},
    pages = {3496–-3504},
    abstract = {The interesting and tunable properties of layered metal dichalcogenides heavily depend on their phase and layer stacking. Here, we show and explain how the layer stacking and physical properties of WSe2 are influenced by screw dislocations. A one-to-one correlation of atomic force microscopy and high- and low-frequency Raman spectroscopy of many dislocated WSe2 nanoplates reveals variations in the number and shapes of dislocation spirals and different layer stackings that are determined by the number, rotation, and location of the dislocations. Plates with triangular dislocation spirals form noncentrosymmetric stacking that gives rise to strong second-harmonic generation and enhanced photoluminescence, plates with hexagonal dislocation spirals form the bulk 2H layer stacking commonly observed, and plates containing mixed dislocation shapes have intermediate noncentrosymmetric stackings with mixed properties. Multiple dislocation cores and other complexities can lead to more complex stackings and properties. These previously unobserved properties and layer stackings in WSe2 will be interesting for spintronics and valleytronics.},
    doi = {10.1021/jacs.6b12559},
    publisher = {American Chemical Society},
    }
  • [DOI] Jared Bozich Mimi Hang, Robert Hamers Rebecca Klaper. Core chemistry influences the toxicity of multi-component metal oxide nanomaterials, lithium nickel manganese cobalt oxide and lithium cobalt oxide to Daphnia magna. Environmental Toxicology and Chemistry 2017, .
    [Bibtex]
    @Article{,
    author = {Jared Bozich, Mimi Hang, Robert Hamers, Rebecca Klaper},
    title = {Core chemistry influences the toxicity of multi-component metal oxide nanomaterials, lithium nickel manganese cobalt oxide and lithium cobalt oxide to Daphnia magna},
    journal = {Environmental Toxicology and Chemistry},
    year = {2017},
    doi = {10.1002/etc.3791},
    }

2016

  • [DOI] Hamers, Robert J. and Jason Bandy. Atmospheric-pressure photoelectron emission from H-terminated and amino-terminated diamond. Physica Status Solidi (a) 2016, .
    [Bibtex]
    @Article{Hamers2016,
    author = {Hamers, Robert J. and Bandy, Jason},
    title = {Atmospheric-pressure photoelectron emission from H-terminated and amino-terminated diamond},
    journal = {Physica Status Solidi (a)},
    year = {2016},
    issn = {1862-6319},
    __markedentry = {[hamers:]},
    doi = {10.1002/pssa.201600152},
    type = {Journal Article},
    }
  • [DOI] Jackson, D. H. K., M. R. Laskar, S. Y. Fang, S. Z. Xu, R. G. Ellis, X. Q. Li, M. Dreibelbis, S. E. Babcock, M. K. Mahanthappa, D. Morgan, R. J. Hamers, and T. F. Kuech. Optimizing AlF3 atomic layer deposition using trimethylaluminum and TaF5: Application to high voltage Li-ion battery cathodes. Journal of Vacuum Science & Technology A 2016, 34, 8.
    [Bibtex]
    @Article{Jackson2016,
    author = {Jackson, D. H. K. and Laskar, M. R. and Fang, S. Y. and Xu, S. Z. and Ellis, R. G. and Li, X. Q. and Dreibelbis, M. and Babcock, S. E. and Mahanthappa, M. K. and Morgan, D. and Hamers, R. J. and Kuech, T. F.},
    title = {Optimizing AlF3 atomic layer deposition using trimethylaluminum and TaF5: Application to high voltage Li-ion battery cathodes},
    journal = {Journal of Vacuum Science \& Technology A},
    year = {2016},
    volume = {34},
    number = {3},
    pages = {8},
    issn = {0734-2101},
    __markedentry = {[hamers:]},
    doi = {10.1116/1.4943385},
    type = {Journal Article},
    }
  • [DOI] Zhang, Lushuai, Susmit Singha Roy, Nathaniel S. Safron, Melinda J. Shearer, Robert M. Jacobberger, Vivek Saraswat, Robert J. Hamers, Michael S. Arnold, and Trisha L. Andrew. Orientation Control of Selected Organic Semiconductor Crystals Achieved by Monolayer Graphene Templates. Advanced Materials Interfaces 2016, 3, .
    [Bibtex]
    @Article{Zhang2016,
    author = {Zhang, Lushuai and Roy, Susmit Singha and Safron, Nathaniel S and Shearer, Melinda J and Jacobberger, Robert M and Saraswat, Vivek and Hamers, Robert J and Arnold, Michael S and Andrew, Trisha L},
    title = {Orientation Control of Selected Organic Semiconductor Crystals Achieved by Monolayer Graphene Templates},
    journal = {Advanced Materials Interfaces},
    year = {2016},
    volume = {3},
    number = {22},
    issn = {2196-7350},
    doi = {10.1002/admi.201600621},
    endnotereftype = {Journal Article},
    shorttitle = {Orientation Control of Selected Organic Semiconductor Crystals Achieved by Monolayer Graphene Templates},
    }
  • [DOI] Marquard, Angela N., Laura E. Slaymaker, Robert J. Hamers, and Randall H. Goldsmith. Investigation of activity, stability, and degradation mechanism of surface-supported Pd-PEPPSI complexes for Suzuki-Miyaura coupling. Journal of Molecular Catalysis A: Chemical 2016, .
    [Bibtex]
    @Article{Marquard2016,
    author = {Marquard, Angela N and Slaymaker, Laura E and Hamers, Robert J and Goldsmith, Randall H},
    title = {Investigation of activity, stability, and degradation mechanism of surface-supported Pd-PEPPSI complexes for Suzuki-Miyaura coupling},
    journal = {Journal of Molecular Catalysis A: Chemical},
    year = {2016},
    issn = {1381-1169},
    doi = {10.1016/j.molcata.2016.12.001},
    endnotereftype = {Journal Article},
    shorttitle = {Investigation of activity, stability, and degradation mechanism of surface-supported Pd-PEPPSI complexes for Suzuki-Miyaura coupling},
    }
  • Hamers, Robert John and Laura Elizabeth Slaymaker. 2016. U.S. Patent Application, "ELECTRICALLY-POLYMERIZED SURFACE LAYER FOR ARTIFICIAL SOLID-ELECTROLYTE-INTERPHASE (SEI) LAYERS ON SILICON AND CARBON BASED ELECTRODES". .
    [Bibtex]
    @Misc{Hamers2016a,
    author = {Hamers, Robert John and Slaymaker, Laura Elizabeth},
    title = {U.S. Patent Application, "ELECTRICALLY-POLYMERIZED SURFACE LAYER FOR ARTIFICIAL SOLID-ELECTROLYTE-INTERPHASE (SEI) LAYERS ON SILICON {AND} CARBON BASED ELECTRODES"},
    howpublished = {US Patent 20,160,020,449},
    year = {2016},
    endnotereftype = {Generic},
    shorttitle = {ELECTRICALLY-POLYMERIZED SURFACE LAYER FOR ARTIFICIAL SOLID-ELECTROLYTE-INTERPHASE (SEI) LAYERS ON SILICON AND CARBON BASED ELECTRODES},
    }
  • [DOI] Hang, Mimi N., Ian L. Gunsolus, Hunter Wayland, Eric S. Melby, Arielle C. Mensch, Katie R. Hurley, Joel A. Pedersen, Christy L. Haynes, and Robert J. Hamers. Impact of Nanoscale Lithium Nickel Manganese Cobalt Oxide (NMC) on the Bacterium Shewanella oneidensis MR-1. Chemistry of Materials 2016, 28, 1092-1100.
    [Bibtex]
    @Article{Hang2016,
    author = {Mimi N. Hang and Ian L. Gunsolus and Hunter Wayland and Eric S. Melby and Arielle C. Mensch and Katie R. Hurley and Joel A. Pedersen and Christy L. Haynes and Robert J. Hamers},
    title = {Impact of Nanoscale Lithium Nickel Manganese Cobalt Oxide (NMC) on the Bacterium Shewanella oneidensis MR-1},
    journal = {Chemistry of Materials},
    year = {2016},
    volume = {28},
    number = {4},
    pages = {1092-1100},
    abstract = { Nickel manganese cobalt oxide (NMC) comprises a class of lithium intercalation compounds with the composition LxNiyMnzCo1-y-zO2 (0 < x,y,z < 1). These compounds are of emerging importance in nanoparticle form as cathode materials for lithium-ion batteries used in transportation and consumer electronics. To evaluate the potential environmental impact of release of this material in the environment, we synthesized NMC nanosheets and investigated their interaction with Shewanella oneidensis, a soil and sediment bacterium. Exposure to 5 mg/L NMC significantly impaired bacterial population growth and respiration. Measurements of NMC surface composition by X-ray photoelectron spectroscopy and of the composition of the suspending solution via inductively coupled plasma-optical emission spectroscopy (ICP-OES) demonstrated incongruent material dissolution and measurable release of all four metal constituents (Li, Mn, Co, and Ni) into solution. Speciation modeling and assessment of bacterial response to metal ion exposure (via cell growth and respiration measurements) established that the observed bacterial inhibition arose from the metal ions released from the NMC, with the largest effects arising from Ni(II) and Co(II) species. },
    doi = {10.1021/acs.chemmater.5b04505},
    eprint = {http://dx.doi.org/10.1021/acs.chemmater.5b04505},
    }
  • [DOI] Bandy, Jason A., Di Zhu, and Robert J. Hamers. Photocatalytic reduction of nitrogen to ammonia on diamond thin films grown on metallic substrates. Diamond and Related Materials 2016, 64, 34-41.
    [Bibtex]
    @Article{Hamers586,
    author = {Jason A. Bandy and Di Zhu and Robert J. Hamers},
    title = {Photocatalytic reduction of nitrogen to ammonia on diamond thin films grown on metallic substrates},
    journal = {Diamond and Related Materials},
    year = {2016},
    volume = {64},
    pages = {34 - 41},
    issn = {0925-9635},
    abstract = {Abstract Recent studies have demonstrated that boron-doped diamond can act as a solid-state source of electrons in water when illuminated with above-bandgap light. Excitation of electrons to diamond's conduction band leads to facile emission of electrons into water; the resulting solvated electrons are potent reducing agents able to initiate many chemical reactions such as the reduction of \{N2\} to \{NH3\} and the reduction of \{CO2\} to CO. Here, we report investigations of the photocatalytic activity of diamond thin films grown on Mo, Ni, and Ti substrates. Our results show that in each case, there is a maximum in the photocatalytic activity that occurs just when the diamond coalesces into a contiguous film, then decreasing as the film becomes thicker. These results suggest that electron emission arises in part from excitation of electrons in the metal substrate, followed by injection into the conduction band of the diamond film. More detailed studies on films grown on niobium show that at the open-circuit potential the films have a downward bend-bending of ~ 0.3 V, which is favorable for barrier-free electron emission. Our result suggests that metal–diamond heterostructures may provide a scalable approach to achieving difficult photocatalytic reactions. },
    doi = {10.1016/j.diamond.2016.01.006},
    keywords = {Diamond film, Plasma CVD, Catalytic processes, Interface electronic properties, Electrochemical },
    }
  • [DOI] Zhu, Di, Jason A. Bandy, Shuo Li, and Robert J. Hamers. Amino-terminated diamond surfaces: Photoelectron emission and photocatalytic properties. Surface Science 2016, 650, 295-301.
    [Bibtex]
    @Article{Hamers587,
    author = {Di Zhu and Jason A. Bandy and Shuo Li and Robert J. Hamers},
    title = {Amino-terminated diamond surfaces: Photoelectron emission and photocatalytic properties},
    journal = {Surface Science},
    year = {2016},
    volume = {650},
    pages = {295 - 301},
    issn = {0039-6028},
    note = {The surface science of heterogeneous catalysis: In honor of Robert J. Madix},
    abstract = {Abstract We report a new approach to making stable negative electron-affinity diamond surfaces by terminating diamond with amino groups (also known as amine groups, —NH2). Previous studies have shown that negative electron affinity can be induced by terminating diamond surfaces with hydrogen, creating a surface dipole favorable toward electron emission. Here, we demonstrate that covalent tethering of positive charges in the form of protonated amino groups, —NH3+, also leads to negative electron affinity (NEA) and facile electron emission into vacuum and into water. Amino-terminated diamond was prepared using a very mild plasma discharge. Valence-band photoemission studies of the amino-terminated diamond samples show a characteristic “NEA” peak, demonstrating that the amino-terminated surface has NEA. Diamond's ability to emit electrons into water was evaluated using photochemical conversion of \{N2\} to NH3. Time-resolved surface photovoltage studies were used to characterize charge separation at the diamond interface, and Mott–Schottky measurements were performed to characterize band-bending at the diamond–water interface. \{XPS\} studies show that the amino-terminated surfaces provide increased chemical resistance to oxidation compared with H-terminated diamond when illuminated with ultraviolet light. },
    doi = {10.1016/j.susc.2016.01.003},
    keywords = {Diamond, Photocatalysis, Amine, Amino, Electron emission, Solvated electrons},
    }
  • [DOI] Liang, Dong, Yuelin Peng, Yongping Fu, Melinda J. Shearer, Jingjing Zhang, Jianyuan Zhai, Yi Zhang, Robert J. Hamers, Trisha L. Andrew, and Song Jin. Color-Pure Violet-Light-Emitting Diodes Based on Layered Lead Halide Perovskite Nanoplates. ACS Nano 2016, 10, 6897-6904.
    [Bibtex]
    @Article{Liang2016,
    author = {Liang, Dong and Peng, Yuelin and Fu, Yongping and Shearer, Melinda J. and Zhang, Jingjing and Zhai, Jianyuan and Zhang, Yi and Hamers, Robert J. and Andrew, Trisha L. and Jin, Song},
    title = {Color-Pure Violet-Light-Emitting Diodes Based on Layered Lead Halide Perovskite Nanoplates},
    journal = {ACS Nano},
    year = {2016},
    volume = {10},
    number = {7},
    pages = {6897-6904},
    issn = {1936-0851},
    doi = {10.1021/acsnano.6b02683},
    type = {Journal Article},
    }
  • [DOI] Laskar, Masihhur R., David H. K. Jackson, Yingxin Guan, Shenzhen Xu, Shuyu Fang, Mark Dreibelbis, Mahesh K. Mahanthappa, Dane Morgan, Robert J. Hamers, and Thomas F. Kuech. Atomic Layer Deposition of Al2O3–Ga2O3 Alloy Coatings for Li[Ni0.5Mn0.3Co0.2]O2 Cathode to Improve Rate Performance in Li-Ion Battery. ACS Applied Materials & Interfaces 2016, 8, 10572-10580.
    [Bibtex]
    @Article{Laskar2016,
    author = {Masihhur R. Laskar and David H. K. Jackson and Yingxin Guan and Shenzhen Xu and Shuyu Fang and Mark Dreibelbis and Mahesh K. Mahanthappa and Dane Morgan and Robert J. Hamers and Thomas F. Kuech},
    title = {Atomic Layer Deposition of Al2O3–Ga2O3 Alloy Coatings for Li[Ni0.5Mn0.3Co0.2]O2 Cathode to Improve Rate Performance in Li-Ion Battery},
    journal = {ACS Applied Materials \& Interfaces},
    year = {2016},
    volume = {8},
    number = {16},
    pages = {10572-10580},
    note = {PMID: 27035035},
    abstract = { Metal oxide coatings can improve the electrochemical stability of cathodes and hence, their cycle-life in rechargeable batteries. However, such coatings often impose an additional electrical and ionic transport resistance to cathode surfaces leading to poor charge–discharge capacity at high C-rates. Here, a mixed oxide (Al2O3)1–x(Ga2O3)x alloy coating, prepared via atomic layer deposition (ALD), on Li[Ni0.5Mn0.3Co0.2]O2 (NMC) cathodes is developed that has increased electron conductivity and demonstrated an improved rate performance in comparison to uncoated NMC. A “co-pulsing” ALD technique was used which allows intimate and controlled ternary mixing of deposited film to obtain nanometer-thick mixed oxide coatings. Co-pulsing allows for independent control over film composition and thickness in contrast to separate sequential pulsing of the metal sources. (Al2O3)1–x(Ga2O3)x alloy coatings were demonstrated to improve the cycle life of the battery. Cycle tests show that increasing Al-content in alloy coatings increases capacity retention; whereas a mixture of compositions near (Al2O3)0.5(Ga2O3)0.5 was found to produce the optimal rate performance. },
    doi = {10.1021/acsami.5b11878},
    eprint = {http://dx.doi.org/10.1021/acsami.5b11878},
    }
  • [DOI] Melby, Eric S., Arielle C. Mensch, Samuel E. Lohse, Dehong Hu, Galya Orr, Catherine J. Murphy, Robert J. Hamers, and Joel A. Pedersen. Formation of supported lipid bilayers containing phase-segregated domains and their interaction with gold nanoparticles. Environ. Sci.: Nano 2016, 3, 45-55.
    [Bibtex]
    @Article{Melby2016,
    author = {Melby, Eric S. and Mensch, Arielle C. and Lohse, Samuel E. and Hu, Dehong and Orr, Galya and Murphy, Catherine J. and Hamers, Robert J. and Pedersen, Joel A.},
    title = {Formation of supported lipid bilayers containing phase-segregated domains and their interaction with gold nanoparticles},
    journal = {Environ. Sci.: Nano},
    year = {2016},
    volume = {3},
    pages = {45-55},
    abstract = {For nanoparticles that have been released into the environment{,} the cell membrane represents an initial site of interaction with eukaryotic cells. The encounter of nanoparticles with cellular membranes may alter membrane structure and function{,} lead to uptake into cells{,} or elicit adverse biological responses. Supported lipid bilayers have proven to be valuable ex vivo models for biological membranes{,} allowing investigation of their mechanisms of interaction with nanoparticles with a degree of control impossible in living cells. To date{,} the majority of research on nanoparticle interaction with supported lipid bilayers has employed membranes composed of single or binary mixtures of phospholipids. Cellular membranes contain a wide variety of lipids and exhibit lateral organization. Ordered membrane domains enriched in specific membrane components{,} also referred to as lipid rafts{,} have not been explored with respect to their interaction with nanoparticles. Here we develop model membranes containing segregated domains differing in fluidity that are amenable to investigation by a variety of surface-sensitive analytical techniques and demonstrate that these domains influence the extent of nanoparticle attachment to model membranes. We determined conditions that allow reliable formation of bilayers containing liquid-ordered domains enriched in sphingomyelin and cholesterol and confirmed their morphology by structured illumination and atomic force microscopies. We demonstrate that the presence of liquid-ordered domains increases attachment of cationic gold nanoparticles to model membranes relative to those lacking such domains under near physiological ionic strength conditions (0.1 M NaCl) at pH 7.4. We anticipate that these results will serve as the foundation for and motivate further study of nanoparticle interaction with phase-segregated domains.},
    doi = {10.1039/C5EN00098J},
    issue = {1},
    publisher = {The Royal Society of Chemistry},
    }
  • [DOI] Troiano, Julianne M., Thomas R. Kuech, Ariane M. Vartanian, Marco D. Torelli, Akash Sen, Lisa M. Jacob, Robert J. Hamers, Catherine J. Murphy, Joel A. Pedersen, and Franz M. Geiger. On Electronic and Charge Interference in Second Harmonic Generation Responses from Gold Metal Nanoparticles at Supported Lipid Bilayers. The Journal of Physical Chemistry C 2016, 1-1000.
    [Bibtex]
    @Article{Troiano2016,
    author = {Julianne M. Troiano and Thomas R. Kuech and Ariane M. Vartanian and Marco D. Torelli and Akash Sen and Lisa M. Jacob and Robert J. Hamers and Catherine J. Murphy and Joel A. Pedersen and Franz M. Geiger},
    title = {On Electronic and Charge Interference in Second Harmonic Generation Responses from Gold Metal Nanoparticles at Supported Lipid Bilayers},
    journal = {The Journal of Physical Chemistry C},
    year = {2016},
    volume = {0},
    number = {0},
    pages = {1-1000},
    abstract = { Second harmonic generation (SHG) is useful for studying the properties of interfaces, including the surfaces of nanoparticles and the interaction of nanoparticles with biologically relevant surfaces. Gold nanoparticles at the biological membrane represent a particularly interesting system to be probed by SHG spectroscopy given the rich electronic structure of gold nanoparticles and the charged nature of the nano-bio interface. Here we describe the interplay between the resonant and nonresonant components of the second harmonic response as 4 and 14 nm spherical gold nanoparticles (AuNPs) wrapped in the cationic polyelectrolyte poly(allylamine hydrochloride) (PAH) adsorb to negatively charged supported lipid bilayers. In contrast to the SHG response of 4 nm PAH-AuNPs, that we have shown previously to be dominated by resonance enhancement, the SHG response from the adsorption of the 14 nm PAH-AuNPs, with similar hydrodynamic diameters, to a 9:1 DOPC:DOTAP bilayer is dominated by the nonresonant, interfacial, potential-dependent component of the signal. We hypothesize that the difference in the SHG response is attributable to the differences in the number of PAH molecules associated with the particles and, therefore, differences in the number of positively charged ammonium groups associated with the 4 vs the 14 nm particles. For 14 nm PAH-AuNPs with larger hydrodynamic diameters, we determined two regimes in the adsorption behavior, one where the resonance enhancement from the gold core of the nanoparticle dominates the signal and a second where the nonresonant, interfacial, potential-dependent term dominates the signal. The results presented in this study provide insight into the interplay between resonant and nonresonant components of the second harmonic signal from the adsorption of charged AuNPs and are valuable for future studies with other functionalized particles and lipid systems by SHG. },
    doi = {10.1021/acs.jpcc.6b01786},
    eprint = {http://dx.doi.org/10.1021/acs.jpcc.6b01786},
    }
  • Kuech T.R. Hamers, Pedersen R. J. . J. A.. 2016. Chemical transformations of metal, metal oxide, and metal chalcogenide nanoparticles in the environment. Edited by Xing Baoshan Vecitis, Chad Senesi Nicola D.. In Engineered Nanoparticles and the Environment: Biophysicochemical Processes and Toxicity, Wiley. .
    [Bibtex]
    @InBook{Kuech2016,
    title = {Chemical transformations of metal, metal oxide, and metal chalcogenide nanoparticles in the environment},
    publisher = {Wiley},
    year = {2016},
    author = {Kuech, T.R. Hamers, R.J. Pedersen, J.A.},
    editor = {Xing, Baoshan Vecitis, Chad D. Senesi, Nicola},
    isbn = {978-1-119-27582-4},
    booktitle = {Engineered Nanoparticles and the Environment: Biophysicochemical Processes and Toxicity},
    }

2015

  • [DOI] Dogangun, M., M. N. Hang, J. M. Troiano, A. C. McGeachy, E. S. Melby, J. A. Pedersen, R. J. Hamers, and F. M. Geiger. Alteration of Membrane Compositional Asymmetry by LiCoO2 Nanosheets. Acs Nano 2015, 9, 8755-8765.
    [Bibtex]
    @Article{Hamers540,
    Title = {Alteration of Membrane Compositional Asymmetry by LiCoO2 Nanosheets},
    Author = {Dogangun, M. and Hang, M. N. and Troiano, J. M. and McGeachy, A. C. and Melby, E. S. and Pedersen, J. A. and Hamers, R. J. and Geiger, F. M.},
    Journal = {Acs Nano},
    Year = {2015},
    Note = {ISI Document Delivery No.: CS2XR
    Times Cited: 0
    Cited Reference Count: 80
    Doganguen, Merve Hang, Mimi N. Troiano, Julianne M. McGeachy, Alicia C. Melby, Eric S. Pedersen, Joel A. Hamers, Robert J. Geiger, Franz M.
    National Science Foundation Centers for Chemical Innovation Program, the Center For Sustainable Nanotechnology [CHE-1240151]; International Institute for Nanotechnology; Keck Foundation; State of Illinois; Northwestern University; MRSEC [NSF DMR-1121262]
    This study was supported by the National Science Foundation Centers for Chemical Innovation Program, the Center For Sustainable Nanotechnology, under Grant No. CHE-1240151. The ToF-SIMS work was performed in the Keck-II facility of NUANCE Center at Northwestern University. The NUANCE Center is supported by the International Institute for Nanotechnology, MRSEC (NSF DMR-1121262), the Keck Foundation, the State of Illinois, and Northwestern University.
    Amer chemical soc
    Washington},
    Number = {9},
    Pages = {8755-8765},
    Volume = {9},
    Abstract = {Given the projected massive presence of redox-active nanomaterials in the next generation of consumer electronics and electric vehicle batteries, they are likely to eventually come in contact with cell membranes, with biological consequences that are currently not known. Here, we present nonlinear optical studies showing that lithium nickel manganese cobalt oxide nanosheets carrying a negative zeta-potential have no discernible consequences for lipid alignment and interleaflet composition in supported lipid bilayers formed from zwitterionic and negatively charged lipids. In contrast, lithiated and delithiated LiCoO2 nanosheets having positive and neutral zeta-potentials, respectively, alter the compositional asymmetry of the two membrane leaflets, and bilayer asymmetry remains disturbed even after rinsing. The insight that some cobalt oxide nanoformulations induce alterations to the compositional asymmetry in idealized model membranes may represent an important step toward assessing the biological consequences of their predicted widespread use.},
    Doi = {10.1021/acsnano.5b01440},
    ISSN = {1936-0851},
    Keywords = {phospholipid bilayer asymmetry
    nano-bio interface
    sum-frequency
    generation
    secondary ion mass spectrometry
    transbilayer movement
    silica/water interfaces
    frequency vibrational spectroscopy
    supported lipid-bilayers
    lithium-ion batteries
    phospholipid flip-flop
    sum-frequency
    gold
    nanoparticles
    transmembrane peptides
    mass-spectrometry
    functional-group
    facile synthesis},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000361935800014}
    }
  • [DOI] Fu, Y. P., F. Meng, M. B. Rowley, B. J. Thompson, M. J. Shearer, D. W. Ma, R. J. Hamers, J. C. Wright, and S. Jin. Solution Growth of Single Crystal Methylammonium Lead Halide Perovskite Nanostructures for Optoelectronic and Photovoltaic Applications. Journal of the American Chemical Society 2015, 137, 5810-5818.
    [Bibtex]
    @Article{Hamers541,
    Title = {Solution Growth of Single Crystal Methylammonium Lead Halide Perovskite Nanostructures for Optoelectronic and Photovoltaic Applications},
    Author = {Fu, Y. P. and Meng, F. and Rowley, M. B. and Thompson, B. J. and Shearer, M. J. and Ma, D. W. and Hamers, R. J. and Wright, J. C. and Jin, S.},
    Journal = {Journal of the American Chemical Society},
    Year = {2015},
    Note = {ISI Document Delivery No.: CH9EJ
    Times Cited: 8
    Cited Reference Count: 63
    Fu, Yongping Meng, Fei Rowley, Matthew B. Thompson, Blaise J. Shearer, Melinda J. Ma, Dewei Hamers, Robert J. Wright, John C. Jin, Song
    U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering [DE-FG02-09ER46664]; China Scholarship Council (CSC)
    This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Award DE-FG02-09ER46664. D.M. thanks the China Scholarship Council (CSC) for support.
    Amer chemical soc
    Washington},
    Number = {17},
    Pages = {5810-5818},
    Volume = {137},
    Abstract = {Understanding crystal growth and improving material quality is important for improving semiconductors for electronic, optoelectronic, and photovoltaic applications. Amidst the surging interest in solar cells based on hybrid organic inorganic lead halide perovskites and the exciting progress in device performance, improved understanding and better control of the crystal growth of these perovskites could further boost their optoelectronic and photovoltaic performance. Here, we report new insights on the crystal growth of the perovskite materials, especially crystalline nanostructures. Specifically, single crystal nanowires, nanorods, and nanoplates of methylammonium lead halide perovskites (CH3NH3PbI3 and CH3NH3PbBr3) are successfully grown via a dissolution-recrystallization pathway in a solution synthesis from lead iodide (or lead acetate) films coated on substrates. These single crystal nanostructures display strong room-temperature photoluminescence and long carrier lifetime. We also report that a solid liquid interfacial conversion reaction can create a highly crystalline, nanostructured MAPbI(3) film with micrometer grain size and high surface coverage that enables photovoltaic devices with a power conversion efficiency of 10.6%. These results suggest that single-crystal perovskite nanostructures provide improved photophysical properties that are important for fundamental studies and future applications in nanoscale optoelectronic and photonic devices.},
    Doi = {10.1021/jacs.5b02651},
    ISSN = {0002-7863},
    Keywords = {dislocation-driven growth
    solar-cell applications
    semiconductor
    nanowires
    efficiency
    ch3nh3pbi3
    crystallization
    performance
    diffusion
    transport
    chemistry},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000354338500025}
    }
  • [DOI] Dominguez, G. A., S. E. Lohse, M. D. Torelli, C. J. Murphy, R. J. Hamers, G. Orr, and R. D. Klaper. Effects of charge and surface ligand properties of nanoparticles on oxidative stress and gene expression within the gut of Daphnia magna. Aquatic Toxicology 2015, 162, 1-9.
    [Bibtex]
    @Article{Hamers542,
    Title = {Effects of charge and surface ligand properties of nanoparticles on oxidative stress and gene expression within the gut of Daphnia magna},
    Author = {Dominguez, G. A. and Lohse, S. E. and Torelli, M. D. and Murphy, C. J. and Hamers, R. J. and Orr, G. and Klaper, R. D.},
    Journal = {Aquatic Toxicology},
    Year = {2015},
    Note = {ISI Document Delivery No.: CH2NA
    Times Cited: 0
    Cited Reference Count: 56
    Dominguez, Gustavo A. Lohse, Samuel E. Torelli, Marco D. Murphy, Catherine J. Hamers, Robert J. Orr, Galya Klaper, Rebecca D.
    National Science Foundation Chemistry Division through the Center for Chemical Innovation Program [CHE-1240151]
    This work was funded by the National Science Foundation Chemistry Division through the Center for Chemical Innovation Program (CHE-1240151) to R. Hamers, C. Murphy, G. Orr and R. Klaper.
    Elsevier science bv
    Amsterdam},
    Pages = {1-9},
    Volume = {162},
    Abstract = {Concern has been raised regarding the current and future release of engineered nanomaterials into aquatic environments from industry and other sources. However, not all nanomaterials may cause an environmental impact and identifying which nanomaterials may be of greatest concern has been difficult. It is thought that the surface groups of a functionalized nanoparticles (NPs) may play a significant role in determining their interactions with aquatic organisms, but the way in which surface properties of NPs impact their toxicity in whole organisms has been minimally explored. A major point of interaction of NPs with aquatic organisms is in the gastrointestinal tract as they ingest particulates from the water column or from the sediment. The main goal of this study was to use model gold NP (AuNPs) to evaluate the potential effects of the different surfaces groups on NPs on the gut of an aquatic model organism, Daphnia magna. In this study, we exposed daphnids to a range of AuNPs concentrations and assessed the impact of AuNP exposure in the daphnid gut by measuring reactive oxygen species (ROS) production and expression of genes associated with oxidative stress and general cellular stress: glutathione S-transferase (gst), catalase (cat), heat shock protein 70 (hsp70), and metallothioneinl (mt1). We found ROS formation and gene expression were impacted by both charge and the specific surface ligand used. We detected some degree of ROS production in all NP exposures, but positively charged AuNPs induced a greater ROS response. Similarly, we observed that, compared to controls, both positively charged AuNPs and only one negatively AuNP impacted expression of genes associated with cellular stress. Finally, ligand-AuNP exposures showed a different toxicity and gene expression profile than the ligand alone, indicating a NP specific effect. (C) 2015 Elsevier B.V. All rights reserved.},
    Doi = {10.1016/j.aquatox.2015.02.015},
    ISSN = {0166-445X},
    Keywords = {ROS
    gst
    Gene expression
    Nanotoxicity
    Oxidative stress
    gold nanoparticles
    silver nanoparticles
    different sizes
    memory
    devices
    toxicity
    nanomaterials
    exposure
    water
    tio2
    zno},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000353860700002}
    }
  • [DOI] Samad, L., M. Caban-Acevedo, M. J. Shearer, K. Park, R. J. Hamers, and S. Jin. Direct Chemical Vapor Deposition Synthesis of Phase-Pure Iron Pyrite (FeS2) Thin Films. Chemistry of Materials 2015, 27, 3108-3114.
    [Bibtex]
    @Article{Hamers543,
    Title = {Direct Chemical Vapor Deposition Synthesis of Phase-Pure Iron Pyrite (FeS2) Thin Films},
    Author = {Samad, L. and Caban-Acevedo, M. and Shearer, M. J. and Park, K. and Hamers, R. J. and Jin, S.},
    Journal = {Chemistry of Materials},
    Year = {2015},
    Note = {ISI Document Delivery No.: CH2OZ
    Times Cited: 0
    Cited Reference Count: 52
    Samad, Leith Caban-Acevedo, Miguel Shearer, Melinda J. Park, Kwangsuk Hamers, Robert J. Jin, Song
    U.S. Department of Energy, SunShot NextGen PVII program [DE-EE0005330]; NSF; Research Corporation Scialog Award for Solar Energy Conversion; UW-Madison Vilas Associate Award; U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering [DE-FG02-09ER46664]
    The research was supported by the U.S. Department of Energy, SunShot NextGen PVII program, under award DE-EE0005330. L.S. and M.C.-A. acknowledge support from the NSF Graduate Research Fellowship Program. S.J. also acknowledges a Research Corporation Scialog Award for Solar Energy Conversion and the UW-Madison Vilas Associate Award for support. M.J.S., R.J.H., and S.J. were supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Award DE-FG02-09ER46664 for the surface characterization conducted herein. The authors acknowledge use of instrumentation supported by the UW MRSEC (DMR-1121288) and the UW NSEC (DMR-0832760).
    Amer chemical soc
    Washington},
    Number = {8},
    Pages = {3108-3114},
    Volume = {27},
    Abstract = {Resurgent interest in iron pyrite (FeS2) as an earth-abundant, nontoxic semiconductor for solar applications has resulted in many attempts to grow phase-pure thin films via chemical vapor deposition (CVD). However, all thin films grown via CVD or sulfidation to date have contained marcasite phase or other iron sulfide impurities. Here, we report the use of metallic cobalt pyrite (cattierite; CoS2) thin films as an ideal substrate leading to the first direct growth of phase-pufe iron pyrite thin films via,atmospheric pressure CVD., This synthesis was :achieved by reacting FeCl3 and ditert butyl disulfide (TBDS) at 400-450 degrees C. The products, were confirmed as phase-pure iron pyrite using X-ray diffraction (XRD), Raman, spectroscopy, and energy dispersive X-ray spectroscopy (EDS). In addition to phase-purity, the synthesis produced crystal domains >1 pm and a conformal coating 3-5 pm thick, which are attributed to the <2% lattice mismatch of the isostruetural cattierite substrate. The surface was characterized by ultraviolet and X-ray photoelectron spectroscopy (UPS & XPS) and the electrical properties by electrocheinical impedance spectroscopy (EIS) and Mott-Schottky analysis.. The direct growth of a phase-pure iron pyrite film on a conductive substrate provides the most convenient configuration so far for potential solar cells.},
    Doi = {10.1021/acs.chemmater.5b00664},
    ISSN = {0897-4756},
    Keywords = {atmospheric-pressure
    photovoltaic application
    n-fes2 pyrite
    surface
    growth
    mocvd
    semiconductor
    sulfurization
    nanocrystals
    precursors},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000353865800047}
    }
  • [DOI] Zhang, L. S., S. S. Roy, C. R. English, R. J. Hamers, M. S. Arnold, and T. L. Andrew. Observing Electron Extraction by Mono layer Graphene Using Time-Resolved Surface Photoresponse Measurements. Acs Nano 2015, 9, 2510-2517.
    [Bibtex]
    @Article{Hamers544,
    Title = {Observing Electron Extraction by Mono layer Graphene Using Time-Resolved Surface Photoresponse Measurements},
    Author = {Zhang, L. S. and Roy, S. S. and English, C. R. and Hamers, R. J. and Arnold, M. S. and Andrew, T. L.},
    Journal = {Acs Nano},
    Year = {2015},
    Note = {ISI Document Delivery No.: CE4HN
    Times Cited: 1
    Cited Reference Count: 36
    Zhang, Lushuai Roy, Susmit Singha English, Caroline R. Hamers, Robert J. Arnold, Michael S. Andrew, Trisha L.
    University of Wisconsin Materials Research Science and Engineering Center [DMR-1121288]; National Science Foundation [CBET-1033346]; DOE Office of Science Early Career Research Program through the Office of Basic Energy Sciences [DE-SC0006414]
    The authors gratefully acknowledge support from the University of Wisconsin Materials Research Science and Engineering Center (DMR-1121288). Partial support is acknowledged by M.S.A. and S.S.R. for graphene synthesis and transfer, from the National Science Foundation (Grant Number CBET-1033346) and the DOE Office of Science Early Career Research Program (Grant Number DE-SC0006414) through the Office of Basic Energy Sciences. We thank Prof. Song Jin for providing access to his AFM.
    Amer chemical soc
    Washington},
    Number = {3},
    Pages = {2510-2517},
    Volume = {9},
    Abstract = {Graphene is considered a next-generation electrode for indium tin oxide (ITO)-free organic photovoltaic devices (OPVs). However, to date, limited numbers of OPVs containing surface-Modified graphene electrodes perform as well as ITO-based counterparts, and no devices containing a bare graphene electrode have been reported to yield satisfactory rectification characteristics. In this report, we provide experimental data to learn why. Time-resolved surface photoresponse, measurements on templated pentacene-on-graphene films directly reveal that p-doped monolayer graphene efficiently extracts electrons, not holes, from photo-excited pentacene. Accordingly, a graphene/pentacene/MoO3 heterojunction displays a large surface photoresponse and, by inference, efficient dissociation of photogenerated excitons, with graphene serving as an electron extraction layer and MoO3 as a hole extraction layer. In Contrast, a graphene/pentatehe/C-60 heterojunction yields a comparatively insignificant surface photoresponse because both graphene and C-60 act as competing electron extraction layers. The data presented herein:provide experimental insight for future endeavors involving bare graphene as an electrode for organic,photovoltaic devices and strongly suggest that p-doped graphene is best considered a cathode for OPVs.},
    Doi = {10.1021/acsnano.5b01157},
    ISSN = {1936-0851},
    Keywords = {graphene
    pentacene
    charge extraction
    surface photoresponse
    built-in
    voltage
    organic solar-cells
    chemical-vapor-deposition
    films
    interface
    photovoltaics
    heterostructures
    pentacene
    substrate
    anodes},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000351791800027}
    }
  • [DOI] Berto, T. C., L. H. Zhang, R. J. Hamers, and J. F. Berry. Electrolyte Dependence of CO2 Electroreduction: Tetraalkylammonium Ions Are Not Electrocatalysts. Acs Catalysis 2015, 5, 703-707.
    [Bibtex]
    @Article{Hamers545,
    Title = {Electrolyte Dependence of CO2 Electroreduction: Tetraalkylammonium Ions Are Not Electrocatalysts},
    Author = {Berto, T. C. and Zhang, L. H. and Hamers, R. J. and Berry, J. F.},
    Journal = {Acs Catalysis},
    Year = {2015},
    Note = {ISI Document Delivery No.: CA9WK
    Times Cited: 1
    Cited Reference Count: 23
    Berto, Timothy C. Zhang, Linghong Hamers, Robert J. Berry, John F.
    University of Wisconsin-Madison; National Science Foundation [CHE-1300464]; Air Force Office of Scientific Research [FA9550-12-1-0063]
    We thank the University of Wisconsin-Madison and the National Science Foundation (CHE-1300464) for support of this work. Contributions of L.Z. and R.J.H. on diamond electrodes were supported by the Air Force Office of Scientific Research Award FA9550-12-1-0063.
    Amer chemical soc
    Washington},
    Number = {2},
    Pages = {703-707},
    Volume = {5},
    Abstract = {The ability of tetraalkylammonium ions (NR4+) to facilitate CO, electroreduction at various electrode surfaces has been investigated. Scan rate dependence shows this process to be diffusion-controlled and largely independent of working electrode material. Variation of the R groups on NR4+ is shown to have little effect on the reduction potential, indicating that catalysis via reduced NR4 center dot species, as previously proposed in the literature, is not a viable mechanism for CO, electroreduction. Rather, CO, is reduced via outer-sphere electron transfer according to the mechanism put forth by Saveant and co-workers [Lamy, E.; Nadjo, L.; Saveant, J.-M. J. Electroanal. Chem. 1977, 78, 403-407]. This view is supported by a full analysis of the reaction products, which consist exclusively of CO and CO32-, as well as solvent decomposition products formed at the counter electrode. No degradation of NR4+ ions is observed, which rules out the transient formation of Nit, radical species during electroreduction. However, Li' ions are definitively shown to inhibit CO, reduction, even in the presence of NR4+ ions. This inhibition likely occurs via surface adsorption of the Li+ ions.},
    Doi = {10.1021/cs501641z},
    ISSN = {2155-5435},
    Keywords = {carbon dioxide
    electrochemistry
    tetraalkylammonium
    boron-doped
    diamond
    low proton availability
    carbon-dioxide
    electrochemical reduction
    dimethylformamide
    conversion
    mechanism
    media},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000349275300025}
    }
  • [DOI] Torelli, M. D., R. A. Putans, Y. Z. Tan, S. E. Lohse, C. J. Murphy, and R. J. Hamers. Quantitative Determination of Ligand Densities on Nanomaterials by X-ray Photoelectron Spectroscopy. Acs Applied Materials & Interfaces 2015, 7, 1720-1725.
    [Bibtex]
    @Article{Hamers546,
    Title = {Quantitative Determination of Ligand Densities on Nanomaterials by X-ray Photoelectron Spectroscopy},
    Author = {Torelli, M. D. and Putans, R. A. and Tan, Y. Z. and Lohse, S. E. and Murphy, C. J. and Hamers, R. J.},
    Journal = {Acs Applied Materials \& Interfaces},
    Year = {2015},
    Note = {ISI Document Delivery No.: CA1RG
    Times Cited: 6
    Cited Reference Count: 39
    Torelli, Marco D. Putans, Rebecca A. Tan, Yizheng Lohse, Samuel E. Murphy, Catherine J. Hamers, Robert J.
    National Science Foundation Centers for Chemical Innovation Program [CHE1240151]
    This work was supported by the National Science Foundation Centers for Chemical Innovation Program, Grant CHE1240151, for the Center for Sustainable Nanotechnology.
    Amer chemical soc
    Washington},
    Number = {3},
    Pages = {1720-1725},
    Volume = {7},
    Abstract = {X-ray photoelectron spectroscopy (XPS) is a nearly universal method for quantitative characterization of both organic and inorganic layers on surfaces. When applied to nanoparticles, the analysis is complicated by the strong curvature of the surface and by the fact that the electron attenuation length can be comparable to the diameter of the nanoparticles, making it necessary to explicitly include the shape of the nanoparticle to achieve quantitative analysis. We describe a combined experimental and computational analysis of XPS data for molecular ligands on gold nanoparticles. The analysis includes scattering in both Au core and organic shells and is valid even for nanoparticles having diameters comparable to the electron attenuation length (EAL). To test this model, we show experimentally how varying particle diameter from 1.3 to 6.3 nm leads to a change in the measured AC/AAu peak area ratio, changing by a factor of 15. By analyzing the data in a simple computational model, we demonstrate that ligand densities can be obtained, and, moreover, that the actual ligand densities for these nanoparticles are a constant value of 3.9 +/- 0.2 molecules nm(-2). This model can be easily extended to a wide range of core-shell nanoparticles, providing a simple pathway to extend XPS quantitative analysis to a broader range of nanomaterials.},
    Doi = {10.1021/am507300x},
    ISSN = {1944-8244},
    Keywords = {quantitative XPS
    nanoparticle
    ligand desity
    molecular coverage
    self-assembled monolayers
    gold nanoparticles
    protein adsorption
    normal-alkanethiols
    packing density
    xps analysis
    surfaces
    acid
    nanocrystallites
    attenuation},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000348688700041}
    }
  • [DOI] Zhang, L. S., S. S. Roy, R. J. Hamers, M. S. Arnold, and T. L. Andrew. Molecular Orientation-Dependent Interfacial Energetics and Built-in Voltage Tuned by a Template Graphene Monolayer. Journal of Physical Chemistry C 2015, 119, 45-54.
    [Bibtex]
    @Article{Hamers547,
    Title = {Molecular Orientation-Dependent Interfacial Energetics and Built-in Voltage Tuned by a Template Graphene Monolayer},
    Author = {Zhang, L. S. and Roy, S. S. and Hamers, R. J. and Arnold, M. S. and Andrew, T. L.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2015},
    Note = {ISI Document Delivery No.: AY7MR
    Times Cited: 1
    Cited Reference Count: 66
    Zhang, Lushuai Roy, Susmit Singha Hamers, Robert J. Arnold, Michael S. Andrew, Trisha L.
    University of Wisconsin Materials Research Science and Engineering Center [DMR-1121288]; National Science Foundation [CBET-1033346]; DOE Office of Science Early Career Research Program through Office of Basic Energy Sciences [DE- SC0006414]
    The authors thank Professor Song Jin for sharing access to his AFM instrument. The authors gratefully acknowledge support from the University of Wisconsin Materials Research Science and Engineering Center (DMR-1121288). Partial support is acknowledged by M.S.A. and S.S.R. for graphene synthesis and transfer, from the National Science Foundation (Grant CBET-1033346) and the DOE Office of Science Early Career Research Program (Grant DE- SC0006414) through the Office of Basic Energy Sciences.
    Amer chemical soc
    Washington},
    Number = {1},
    Pages = {45-54},
    Volume = {119},
    Abstract = {Highly transparent and conductive monolayer graphene was used as a template to tune the crystal orientation of pentacene from generic standing-up (001) to lying-down (022) in neat films. Spatially resolved Kelvin probe force microscopy (KPFM) was used to reveal the energy levels of pentacene thin films grown on substrates with and without the template graphene layer, as well as the energy level alignment in various pentacene-containing organicorganic heterojunctions. A correlation between crystal domain orientation and the work function was directly observed using KPFM. Up to 0.36 eV shifts in work function were observed in neat pentacene films over large areas (>0.5 in.(2)) upon orientation transition, likely due to the transition from Fermi level pinning (standing-up pentacene on ITO) to vacuum level alignment (lying-down pentacene on grapheneITO). Morphology-induced energy level shifts versus interfacial electronic equilibration effects were disentangled using atomic force microscopy, KPFM, X-ray diffraction, and Raman data for neat pentacene films and pentacene containing heterojunctions on monolayer graphene. The data detailed herein provide a fundamental picture of the major interfacial effects active in optoelectronic devices containing a bare graphene electrode.},
    Doi = {10.1021/jp508931e},
    ISSN = {1932-7447},
    Keywords = {energy-level alignment
    probe force microscopy
    organic heterojunction
    interfaces
    charge-transfer states
    pentacene thin-films
    solar-cells
    gap states
    semiconductors
    identification
    surfaces},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000347744700007}
    }
  • [DOI] Troiano, J. M., L. L. Olenick, T. R. Kuech, E. S. Melby, D. H. Hu, S. E. Lohse, A. C. Mensch, M. Dogangun, A. M. Vartanian, M. D. Torelli, E. Ehimiaghe, S. R. Walter, L. Fu, C. R. Anderton, Z. H. Zhu, H. F. Wang, G. Orr, C. J. Murphy, R. J. Hamers, J. A. Pedersen, and F. M. Geiger. Direct Probes of 4 nm Diameter Gold Nanoparticles Interacting with Supported Lipid Bilayers. Journal of Physical Chemistry C 2015, 119, 534-546.
    [Bibtex]
    @Article{Hamers548,
    Title = {Direct Probes of 4 nm Diameter Gold Nanoparticles Interacting with Supported Lipid Bilayers},
    Author = {Troiano, J. M. and Olenick, L. L. and Kuech, T. R. and Melby, E. S. and Hu, D. H. and Lohse, S. E. and Mensch, A. C. and Dogangun, M. and Vartanian, A. M. and Torelli, M. D. and Ehimiaghe, E. and Walter, S. R. and Fu, L. and Anderton, C. R. and Zhu, Z. H. and Wang, H. F. and Orr, G. and Murphy, C. J. and Hamers, R. J. and Pedersen, J. A. and Geiger, F. M.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2015},
    Note = {ISI Document Delivery No.: AY7MR
    Times Cited: 3
    Cited Reference Count: 85
    Troiano, Julianne M. Olenick, Laura L. Kuech, Thomas R. Melby, Eric S. Hu, Dehong Lohse, Samuel E. Mensch, Arielle C. Dogangun, Merve Vartanian, Ariane M. Torelli, Marco D. Ehimiaghe, Eseohi Walter, Stephanie R. Fu, Li Anderton, Christopher R. Zhu, Zihua Wang, Hongfei Orr, Galya Murphy, Catherine J. Hamers, Robert J. Pedersen, Joel A. Geiger, Franz M.
    National Science Foundation Center for Chemical Innovation on Sustainable Nanomaterials (CSN) [CHE-1240151]; NSF Graduate Research Fellowship; Department of Energy's Office of Biological and Environmental Research
    This study was supported by the National Science Foundation Center for Chemical Innovation on Sustainable Nanomaterials (CSN) under Grant CHE-1240151. J.M.T. gratefully acknowledges support through an NSF Graduate Research Fellowship. S.R.W. acknowledges an Arnold O. Beckman Scholarship of the Chicago chapter of the Achievement Rewards for College Scientists (ARCS) foundation. Part of the research was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.
    Amer chemical soc
    Washington},
    Number = {1},
    Pages = {534-546},
    Volume = {119},
    Abstract = {This work presents molecular-level investigations of how well-characterized silica-supported phospholipid bilayers formed from either pure DOPC or a 9:1 mixture of DOPC:DOTAP interact with positively and negatively charged 4 nm gold metal nanoparticles at pH 7.4 and NaCl concentrations ranging from 0.001 to 0.1 M. Second harmonic generation (SHG) charge screening measurements indicate the supported bilayers carry a negative interfacial potential. Resonantly enhanced SHG measurements probing electronic transitions within the gold core of the nanoparticles show the particles interact irreversibly with the supported bilayers at a range of concentrations. At 0.1 M NaCl, surface coverages for the particles functionalized with the negatively charged ligand mercaptopropionic acid (MPA) or wrapped in the cationic polyelectrolyte poly(allylamine) hydrochloride (PAH) are estimated from a joint analysis of QCM-D, XPS, AFM, and ToF-SIMS to be roughly 1 x 10 (7) and 1 x 10 (11) particles cm(2), respectively. Results from complementary SHG charge screening experiments point to the possibility that the surface coverage of the MPA-coated particles is more limited by interparticle Coulomb repulsion due to the charges within their hydrodynamic volumes than with the PAH-wrapped particles. Yet, SHG adsorption isotherms indicate that the interaction strength per particle is independent of ionic strength and particle coating, highlighting the importance of multivalent interactions. H-1 NMR spectra of the lipids within vesicles suspended in solution show little change upon interaction with either particle type but indicate loosening of the gold-bound PAH polymer wrapping upon attachment to the vesicles. The thermodynamic, spectroscopic, and electrostatic data presented here may serve to benchmark experimental and computational studies of nanoparticle attachment processes at the nanobio interface.},
    Doi = {10.1021/jp512107z},
    ISSN = {1932-7447},
    Keywords = {atomic-force microscopy
    interfacial water-structure
    sum-frequency
    generation
    spherical nucleic-acids
    nano-bio interface
    2nd-harmonic
    generation
    silica/water interfaces
    phospholipid-bilayers
    magnesium-ions
    double-layer},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000347744700058}
    }
  • [DOI] Feng, Z. V., I. L. Gunsolus, T. A. Qiu, K. R. Hurley, L. H. Nyberg, H. Frew, K. P. Johnson, A. M. Vartanian, L. M. Jacob, S. E. Lohse, M. D. Torelli, R. J. Hamers, C. J. Murphy, and C. L. Haynes. Impacts of gold nanoparticle charge and ligand type on surface binding and toxicity to Gram-negative and Gram-positive bacteria. Chemical Science 2015, 6, 5186-5196.
    [Bibtex]
    @Article{Hamers549,
    Title = {Impacts of gold nanoparticle charge and ligand type on surface binding and toxicity to Gram-negative and Gram-positive bacteria},
    Author = {Feng, Z. V. and Gunsolus, I. L. and Qiu, T. A. and Hurley, K. R. and Nyberg, L. H. and Frew, H. and Johnson, K. P. and Vartanian, A. M. and Jacob, L. M. and Lohse, S. E. and Torelli, M. D. and Hamers, R. J. and Murphy, C. J. and Haynes, C. L.},
    Journal = {Chemical Science},
    Year = {2015},
    Note = {ISI Document Delivery No.: CO5QR
    Times Cited: 0
    Cited Reference Count: 51
    Feng, Z. Vivian Gunsolus, Ian L. Qiu, Tian A. Hurley, Katie R. Nyberg, Lyle H. Frew, Hilena Johnson, Kyle P. Vartanian, Ariane M. Jacob, Lisa M. Lohse, Samuel E. Torelli, Marco D. Hamers, Robert J. Murphy, Catherine J. Haynes, Christy L.
    United States National Science Foundation under the Center for Sustainable Nanotechnology [CHE-1240151]; NSF through the MRSEC program; Minneapolis Torske Klubben Fellowship; University of Minnesota Doctoral Dissertation Fellowship; Lindstrom Fund; Augsburg URGO program
    This work was supported by the United States National Science Foundation under the Center for Sustainable Nanotechnology, CHE-1240151. We thank the University of Minnesota's University Flow Cytometry Resource for flow cytometry analysis, and Fang Zhou at the Characterization Facility for TEM sample microtome preparation. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. ILG gratefully acknowledges support through a Minneapolis Torske Klubben Fellowship. KH acknowledges support from a University of Minnesota Doctoral Dissertation Fellowship. LN and HF acknowledge the support of the Lindstrom Fund and the Augsburg URGO program. We acknowledge all members of the CSN for helpful discussion.
    Royal soc chemistry
    Cambridge},
    Number = {9},
    Pages = {5186-5196},
    Volume = {6},
    Abstract = {Although nanomaterials facilitate significant technological advancement in our society, their potential impacts on the environment are yet to be fully understood. In this study, two environmentally relevant bacteria, Shewanella oneidensis and Bacillus subtilis, have been used as model organisms to elucidate the molecular interactions between these bacterial classes and Au nanoparticles (AuNPs) with well-controlled and well-characterized surface chemistries: anionic 3-mercaptopropionic acid (MPA), cationic 3-mercaptopropylamine (MPNH2), and the cationic polyelectrolyte poly(allylamine hydrochloride) (PAH). The data demonstrate that cationic, especially polyelectrolyte-wrapped AuNPs, were more toxic to both the Gram-negative and Gram-positive bacteria. The levels of toxicity observed were closely related to the percentage of cells with AuNPs associated with the cell surface as measured in situ using flow cytometry. The NP concentration-dependent binding profiles were drastically different for the two bacteria strains, suggesting the critical role of bacterial cell surface chemistry in determining nanoparticle association, and thereby, biological impact.},
    Doi = {10.1039/c5sc00792e},
    ISSN = {2041-6520},
    Keywords = {transmission electron-microscopy
    bacillus-subtilis
    engineered
    nanomaterials
    antimicrobial peptides
    silver nanoparticles
    membrane-vesicles
    risk-assessment
    size
    growth
    shewanella},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000359214100012}
    }
  • [DOI] Zhang, X. W., F. Meng, S. Mao, Q. Ding, M. J. Shearer, M. S. Faber, J. H. Chen, R. J. Hamers, and S. Jin. Amorphous MoSxCly electrocatalyst supported by vertical graphene for efficient electrochemical and photoelectrochemical hydrogen generation. Energy & Environmental Science 2015, 8, 862-868.
    [Bibtex]
    @Article{Hamers550,
    Title = {Amorphous MoSxCly electrocatalyst supported by vertical graphene for efficient electrochemical and photoelectrochemical hydrogen generation},
    Author = {Zhang, X. W. and Meng, F. and Mao, S. and Ding, Q. and Shearer, M. J. and Faber, M. S. and Chen, J. H. and Hamers, R. J. and Jin, S.},
    Journal = {Energy \& Environmental Science},
    Year = {2015},
    Note = {ISI Document Delivery No.: CF0ZZ
    Times Cited: 7
    Cited Reference Count: 56
    Zhang, Xingwang Meng, Fei Mao, Shun Ding, Qi Shearer, Melinda J. Faber, Matthew S. Chen, Junhong Hamers, Robert J. Jin, Song
    U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering [DE-FG02-09ER46664]; NSFC of China [21476201]; NSF Graduate Research Fellowship; U. of Wisconsin-Milwaukee Research Growth Initiative Program
    This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Award DE-FG02-09ER46664. X.Z. thanks the funding of NSFC of China (21476201). M.S.F. acknowledges the support of a NSF Graduate Research Fellowship. J.C. acknowledges the financial support from the U. of Wisconsin-Milwaukee Research Growth Initiative Program.
    Royal soc chemistry
    Cambridge},
    Number = {3},
    Pages = {862-868},
    Volume = {8},
    Abstract = {We report amorphous MoSxCly as a high-performance electrocatalyst for both electrochemical and photoelectrochemical hydrogen generation. This novel ternary electrocatalyst is synthesized via chemical vapour deposition at temperatures lower than those typically used to grow crystalline MoS2 nanostructures and structurally characterized. The MoSxCly electrocatalysts exhibit stable and high catalytic activity toward the hydrogen evolution reaction, as evidenced by large cathodic current densities at low overpotentials and low Tafel slopes (ca. 50 mV decade(-1)). The electrocatalytic performance can be further enhanced through depositing MoSxCly on conducting vertical graphenes. Furthermore, MoSxCly can be directly deposited on p-type silicon photocathodes to enable efficient photoelectrochemical hydrogen evolution.},
    Doi = {10.1039/c4ee03240c},
    ISSN = {1754-5692},
    Keywords = {chemical-vapor-deposition
    mos2 ultrathin nanosheets
    exfoliated
    metallic mos2
    active edge sites
    evolution reaction
    molybdenum
    sulfides
    catalytic-activity
    oriented graphene
    hybrid
    growth},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000352274600011}
    }
  • [DOI] Czech, Kyle J., Blaise J. Thompson, Schuyler Kain, Qi Ding, Melinda J. Shearer, Robert J. Hamers, Song Jin, and John C. Wright. Measurement of Ultrafast Excitonic Dynamics of Few-Layer MoS2 Using State-Selective Coherent Multidimensional Spectroscopy. Acs Nano 2015, 9, 12146-12157.
    [Bibtex]
    @Article{Hamers581,
    Title = {Measurement of Ultrafast Excitonic Dynamics of Few-Layer MoS2 Using State-Selective Coherent Multidimensional Spectroscopy},
    Author = {Czech, Kyle J. and Thompson, Blaise J. and Kain, Schuyler and Ding, Qi and Shearer, Melinda J. and Hamers, Robert J. and Jin, Song and Wright, John C.},
    Journal = {Acs Nano},
    Year = {2015},
    Note = {Times Cited: 0},
    Number = {12},
    Pages = {12146-12157},
    Volume = {9},
    Doi = {10.1021/acsnano.5b05198},
    ISSN = {1936-0851},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000367280100063}
    }
  • [DOI] Ding, Qi, Jianyuan Zhai, Miguel Caban-Acevedo, Melinda J. Shearer, Linsen Li, Hung-Chih Chang, Meng-Lin Tsai, Dewei Ma, Xingwang Zhang, Robert J. Hamers, Jr-Hau He, and Song Jin. Designing Efficient Solar-Driven Hydrogen Evolution Photocathodes Using Semitransparent MoQ(x)Cl(y) (Q = S, Se) Catalysts on Si Micropyramids. Advanced Materials 2015, 27, 6511-+.
    [Bibtex]
    @Article{Hamers582,
    Title = {Designing Efficient Solar-Driven Hydrogen Evolution Photocathodes Using Semitransparent MoQ(x)Cl(y) (Q = S, Se) Catalysts on Si Micropyramids},
    Author = {Ding, Qi and Zhai, Jianyuan and Caban-Acevedo, Miguel and Shearer, Melinda J. and Li, Linsen and Chang, Hung-Chih and Tsai, Meng-Lin and Ma, Dewei and Zhang, Xingwang and Hamers, Robert J. and He, Jr-Hau and Jin, Song},
    Journal = {Advanced Materials},
    Year = {2015},
    Note = {Times Cited: 0},
    Number = {41},
    Pages = {6511-+},
    Volume = {27},
    Doi = {10.1002/adma.201501884},
    ISSN = {0935-9648},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000364343700030}
    }
  • [DOI] English, Caroline R. and Robert J. Hamers. Molecular Electronic Effects on the Thermal Grafting of Aryl Iodides to TiO2 Surfaces. Journal of Physical Chemistry C 2015, 119, 27972-27981.
    [Bibtex]
    @Article{Hamers583,
    Title = {Molecular Electronic Effects on the Thermal Grafting of Aryl Iodides to TiO2 Surfaces},
    Author = {English, Caroline R. and Hamers, Robert J.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2015},
    Note = {Times Cited: 0},
    Number = {50},
    Pages = {27972-27981},
    Volume = {119},
    Doi = {10.1021/acs.jpcc.5b08333},
    ISSN = {1932-7447},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000366878500012}
    }

2014

  • [DOI] Caban-Acevedo, M., N. S. Kaiser, C. R. English, D. Liang, B. J. Thompson, H. E. Chen, K. J. Czech, J. C. Wright, R. J. Hamers, and S. Jin. Ionization of High-Density Deep Donor Defect States Explains the Low Photovoltage of Iron Pyrite Single Crystals. Journal of the American Chemical Society 2014, 136, 17163-17179.
    [Bibtex]
    @Article{Hamers551,
    Title = {Ionization of High-Density Deep Donor Defect States Explains the Low Photovoltage of Iron Pyrite Single Crystals},
    Author = {Caban-Acevedo, M. and Kaiser, N. S. and English, C. R. and Liang, D. and Thompson, B. J. and Chen, H. E. and Czech, K. J. and Wright, J. C. and Hamers, R. J. and Jin, S.},
    Journal = {Journal of the American Chemical Society},
    Year = {2014},
    Note = {ISI Document Delivery No.: AW8YC
    Times Cited: 5
    Cited Reference Count: 103
    Caban-Acevedo, Miguel Kaiser, Nicholas S. English, Caroline R. Liang, Dong Thompson, Blaise J. Chen, Hong-En Czech, Kyle J. Wright, John C. Hamers, Robert J. Jin, Song
    U.S. Department of Energy, SunShot NextGen PV II program [DE-EE0005330]; NSF Graduate Research Fellowship; U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering [DE-FG02-09ER46664]; Research Corporation Scialog Award for Solar Energy Conversion; UW-Madison Vilas Associate Award; UW-Madison College of Engineering, Materials Research Science and Engineering Center (NSF) [DMR-1121288]; Nanoscale Science and Engineering Center (NSF) [DMR-0832760]
    The research was supported by the U.S. Department of Energy, SunShot NextGen PV II program under Award DE-EE0005330 (to S.J.). M.C.-A. thanks the NSF Graduate Research Fellowship for support. S.J., J.C.W., C.R.E., B.J.T., and K.J.C. also thank the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Award DE-FG02-09ER46664 for support of the diverse spectroscopic and surface analysis of the materials. S.J. also thanks the Research Corporation Scialog Award for Solar Energy Conversion and UW-Madison Vilas Associate Award for support. XPS characterization was performed on instrumentation supported by the UW-Madison College of Engineering, Materials Research Science and Engineering Center (NSF DMR-1121288), and Nanoscale Science and Engineering Center (NSF DMR-0832760). We thank Ms. Melinda Shearer for assistance with XPS measurements. We thank Ms. Kristin Stafford and Prof. Kyoung-Shin Choi for their assistance with the UV-vis-NIR measurements.
    Amer chemical soc
    Washington},
    Number = {49},
    Pages = {17163-17179},
    Volume = {136},
    Abstract = {Iron pyrite (FeS2) is considered a promising earth-abundant semiconductor for solar energy conversion with the potential to achieve terawatt-scale deployment. However, despite extensive efforts and progress, the solar conversion efficiency of iron pyrite remains below 3%, primarily due to a low open circuit voltage (V-OC). Here we report a comprehensive investigation on {100}-faceted n-type iron pyrite single crystals to understand its puzzling low V-OC. We utilized electrical transport, optical spectroscopy, surface photovoltage, photoelectrochemical measurements in aqueous and acetonitrile electrolytes, UV and X-ray photoelectron spectroscopy, and Kelvin force microscopy to characterize the bulk and surface defect states and their influence on the semiconducting properties and solar conversion efficiency of iron pyrite single crystals. These insights were used to develop a circuit model analysis for the electrochemical impedance spectroscopy that allowed a complete characterization of the bulk and surface defect states and the construction of a detailed energy band diagram for iron pyrite crystals. A holistic evaluation revealed that the high-density of intrinsic surface states cannot satisfactorily explain the low photovoltage; instead, the ionization of high-density bulk deep donor states, likely resulting from bulk sulfur vacancies, creates a nonconstant charge distribution and a very narrow surface space charge region that limits the total barrier height, thus satisfactorily explaining the limited photovoltage and poor photoconversion efficiency of iron pyrite single crystals. These findings lead to suggestions to improve single crystal pyrite and nanocrystalline or polycrystalline pyrite films for successful solar applications.},
    Doi = {10.1021/ja509142w},
    ISSN = {0002-7863},
    Keywords = {thin-films
    surface-states
    solar-cells
    band-gap
    fes2 nanocrystals
    photoelectron-spectroscopy
    semiconductor electrodes
    angular-distributions
    electrical-properties
    energy-conversion},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000346544200033}
    }
  • [DOI] Kapilashrami, M., G. Conti, I. Zegkinoglou, S. Nemsak, C. S. Conlon, T. Torndahl, V. Fjallstrom, J. Lischner, S. G. Louie, R. J. Hamers, L. Zhang, J. H. Guo, C. S. Fadley, and F. J. Himpsel. Boron Doped diamond films as electron donors in photovoltaics: An X-ray absorption and hard X-ray photoemission study. Journal of Applied Physics 2014, 116, .
    [Bibtex]
    @Article{Hamers553,
    Title = {Boron Doped diamond films as electron donors in photovoltaics: An X-ray absorption and hard X-ray photoemission study},
    Author = {Kapilashrami, M. and Conti, G. and Zegkinoglou, I. and Nemsak, S. and Conlon, C. S. and Torndahl, T. and Fjallstrom, V. and Lischner, J. and Louie, S. G. and Hamers, R. J. and Zhang, L. and Guo, J. H. and Fadley, C. S. and Himpsel, F. J.},
    Journal = {Journal of Applied Physics},
    Year = {2014},
    Note = {ISI Document Delivery No.: AS0SH
    Times Cited: 0
    Cited Reference Count: 44
    Kapilashrami, M. Conti, G. Zegkinoglou, I. Nemsak, S. Conlon, C. S. Torndahl, T. Fjallstrom, V. Lischner, J. Louie, Steven G. Hamers, R. J. Zhang, L. Guo, J. -H. Fadley, C. S. Himpsel, F. J.
    Department of Energy, Basic Energy Sciences [DE-SC0006931, DE-AC02-05CH11231, DE-FG02-01ER45917]; Department of Energy, Basic Energy Sciences via the Lawrence Berkeley National Laboratory Materials Sciences Division [DE-AC02-05CH11231]; National Science Foundation [DMR-1207281, DMR10-1006184]; SciDAC Program on Excited State Phenomena in Energy Materials - U. S. Department of Energy, Basic Energy Sciences and Advanced Scientific Computing Research at the Lawrence Berkeley National Laboratory [DE-AC02-05CH11231]; APTCOM Project of the Triangle de Physique, Paris
    This work was supported by the Department of Energy, Basic Energy Sciences, under Contract Nos. DE-SC0006931, DE-AC02-05CH11231 (ALS), and DE-FG02-01ER45917 (end station). The authors thank Dr. Lyuba Belova and Dr. Anastasia Riazanova at Royal Institute of Technology for their timely help with high-resolution electron microscopy studies on the morphology of the CIGS samples. G. C, S.N., C. S. C., and C. F. also acknowledge the support of the Department of Energy, Basic Energy Sciences, under Contract DE-AC02-05CH11231, via the Lawrence Berkeley National Laboratory Materials Sciences Division. R.J.H. and L.Z. acknowledge the National Science Foundation DMR-1207281 (diamond sample preparation). Theoretical studies were supported by the SciDAC Program on Excited State Phenomena in Energy Materials funded by the U. S. Department of Energy, Basic Energy Sciences and Advanced Scientific Computing Research, under Contract No. DE-AC02-05CH11231 at the Lawrence Berkeley National Laboratory (GW quasiparticle computations and algorithm and code development), and by the National Science Foundation under grant DMR10-1006184 (basic theory and analysis). C.S.F. is also grateful for support from the APTCOM Project of the Triangle de Physique, Paris.
    Amer inst physics
    Melville},
    Number = {14},
    Volume = {116},
    Abstract = {Highly boron-doped diamond films are investigated for their potential as transparent electron donors in solar cells. Specifically, the valence band offset between a diamond film (as electron donor) and Cu(In,Ga)Se-2 (CIGS) as light absorber is determined by a combination of soft X-ray absorption spectroscopy and hard X-ray photoelectron spectroscopy, which is more depth-penetrating than standard soft X-ray photoelectron spectroscopy. In addition, a theoretical analysis of the valence band is performed, based on GW quasiparticle band calculations. The valence band offset is found to be small: VBO = VBMCIGS -VBMdiamond = 0.3 eV +/- 0.1 eV at the CIGS/Diamond interface and 0.0 eV +/- 0.1 eV from CIGS to bulk diamond. These results provide a promising starting point for optimizing the band offset by choosing absorber materials with a slightly lower valence band maximum. (C) 2014 AIP Publishing LLC.},
    Doi = {10.1063/1.4897166},
    ISSN = {0021-8979},
    Keywords = {solar-cells
    core exciton
    photoelectron-spectroscopy
    nanocrystalline
    diamond
    precise determination
    quasi-particle
    surfaces
    affinity
    conduction
    energy},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000343988000019}
    }
  • [DOI] Bishop, L. M., A. S. Tillman, F. M. Geiger, C. L. Haynes, R. D. Klaper, C. J. Murphy, G. Orr, J. A. Pedersen, L. DeStefano, and R. J. Hamers. Enhancing Graduate Student Communication to General Audiences through Blogging about Nanotechnology and Sustainability. Journal of Chemical Education 2014, 91, 1600-1605.
    [Bibtex]
    @Article{Hamers554,
    Title = {Enhancing Graduate Student Communication to General Audiences through Blogging about Nanotechnology and Sustainability},
    Author = {Bishop, L. M. and Tillman, A. S. and Geiger, F. M. and Haynes, C. L. and Klaper, R. D. and Murphy, C. J. and Orr, G. and Pedersen, J. A. and DeStefano, L. and Hamers, R. J.},
    Journal = {Journal of Chemical Education},
    Year = {2014},
    Note = {ISI Document Delivery No.: AR6GT
    Times Cited: 3
    Cited Reference Count: 38
    Bishop, Lee M. Tillman, Ayesha S. Geiger, Franz M. Haynes, Christy L. Klaper, Rebecca D. Murphy, Catherine J. Orr, Galya Pedersen, Joel A. DeStefano, Lizanne Hamers, Robert J.
    National Science Foundation Chemistry Division under the Center for Sustainable Nanotechnology [CHE-1240151]
    This material is based upon work supported by the National Science Foundation Chemistry Division under the Center for Sustainable Nanotechnology, CHE-1240151. The authors would like to thank the following blog writers and peer editors, without whom this project would not have been possible: Devrah Arndt, Jared S. Bozich, Merve Dogangun, Gustavo A. Dominguez, Eseohi Ehimiaghe, Ian L. Gunsolus, Mimi N. Hang, Kurt H. Jacobson, Thomas R. Kuech, Changsoo Lee, Samuel E. Lohse, Nelliza Medero, Eric S. Melby, Arielle C. Mensch, Ben M. Meyer, Elvin A. Morales, Adam Nikolaus, Laura Olenick, Becca Putans, Tian A. Qiu, Stephanie Sanders, Marco D. Torelli, Julianne M. Troiano, Ariane Vartanian, Stephanie R. Walter.
    Amer chemical soc
    Washington},
    Number = {10},
    Pages = {1600-1605},
    Volume = {91},
    Abstract = {We have developed and assessed a multiauthor science blog on the topic of nanotechnology and sustainability as a tool to improve the written communication and public engagement skills of graduate students. Focus group studies revealed that after participation in the blog, student authors felt more confident and capable of communicating technical topics to general audiences. Students' research mentors viewed this as an important component of their students' education, as indicated by survey data. Important design aspects of this effort include participation of an editor as well as having flexible content and target-audience guidelines. We have explicitly outlined aspects of the effort we see as critical in order to enable others to replicate this model in related settings.},
    Doi = {10.1021/ed500050d},
    ISSN = {0021-9584},
    Keywords = {Graduate Education/Research
    Curriculum
    Public Understanding/Outreach
    Communication/Writing
    Internet/Web-Based Learning
    Professional
    Development
    Nanotechnology
    chemistry course
    public outreach
    skills
    education
    scientists},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000343682000013}
    }
  • [DOI] Zhang, L. H., D. Zhu, G. M. Nathanson, and R. J. Hamers. Selective Photoelectrochemical Reduction of Aqueous CO2 to CO by Solvated Electrons. Angewandte Chemie-International Edition 2014, 53, 9746-+.
    [Bibtex]
    @Article{Hamers555,
    Title = {Selective Photoelectrochemical Reduction of Aqueous CO2 to CO by Solvated Electrons},
    Author = {Zhang, L. H. and Zhu, D. and Nathanson, G. M. and Hamers, R. J.},
    Journal = {Angewandte Chemie-International Edition},
    Year = {2014},
    Note = {ISI Document Delivery No.: AQ3GH
    Times Cited: 5
    Cited Reference Count: 32
    Zhang, Linghong Zhu, Di Nathanson, Gilbert M. Hamers, Robert J.
    Air Force Office of Scientific Research under AFOSR [FA9550-12-1-0063]
    This work was supported by the Air Force Office of Scientific Research under AFOSR Award FA9550-12-1-0063. L.Z. thanks Fei Meng for assistance of X-ray diffraction measurements, Steve Strebel, LeRoy Dobson, and Christopher McSweeny at Wisconsin State Laboratory of Hygiene for the assistance of ion chromatography measurements.
    Wiley-v c h verlag gmbh
    Weinheim},
    Number = {37},
    Pages = {9746-+},
    Volume = {53},
    Abstract = {Reduction of CO2 by direct one-electron activation is extraordinarily difficult because of the -1.9V reduction potential of CO2. Demonstrated herein is reduction of aqueous CO2 to CO with greater than 90% product selectivity by direct one-electron reduction to CO2.- by solvated electrons. Illumination of inexpensive diamond substrates with UV light leads to the emission of electrons directly into water, where they form solvated electrons and induce reduction of CO2 to CO2.-. Studies using diamond were supported by studies using aqueous iodide ion (I-), a chemical source of solvated electrons. Both sources produced CO with high selectivity and minimal formation of H-2. The ability to initiate reduction reactions by emitting electrons directly into solution without surface adsorption enables new pathways which are not accessible using conventional electrochemical or photochemical processes.},
    Doi = {10.1002/anie.201404328},
    ISSN = {1433-7851},
    Keywords = {carbon dioxide
    diamond
    photochemistry
    reduction
    surface chemistry
    electrochemical reduction
    carbon-dioxide
    potentials
    diamond
    mechanism
    radicals
    water
    photocatalysis
    conversion
    surfaces},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000342678200001}
    }
  • [DOI] Lukowski, M. A., A. S. Daniel, C. R. English, F. Meng, A. Forticaux, R. J. Hamers, and S. Jin. Highly active hydrogen evolution catalysis from metallic WS2 nanosheets. Energy & Environmental Science 2014, 7, 2608-2613.
    [Bibtex]
    @Article{Hamers556,
    Title = {Highly active hydrogen evolution catalysis from metallic WS2 nanosheets},
    Author = {Lukowski, M. A. and Daniel, A. S. and English, C. R. and Meng, F. and Forticaux, A. and Hamers, R. J. and Jin, S.},
    Journal = {Energy \& Environmental Science},
    Year = {2014},
    Note = {ISI Document Delivery No.: AM4YJ
    Times Cited: 60
    Cited Reference Count: 39
    Lukowski, Mark A. Daniel, Andrew S. English, Caroline R. Meng, Fei Forticaux, Audrey Hamers, Robert J. Jin, Song
    U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering [DE-FG02-09ER46664]; Research Corporation Scialog Award; UW-Madison H. I. Romnes Faculty Fellowship
    This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Award DE-FG02-09ER46664. S.J. also thanks Research Corporation Scialog Award and the UW-Madison H. I. Romnes Faculty Fellowship for support. We thank Eric Melby and Professor Joel Pedersen for their assistance in the QCM measurement.
    Royal soc chemistry
    Cambridge},
    Number = {8},
    Pages = {2608-2613},
    Volume = {7},
    Abstract = {We report metallic WS2 nanosheets that display excellent catalytic activity for hydrogen evolution reaction (HER) that is the best reported for MX2 materials. They are chemically exfoliated from WS2 nanostructures synthesized by chemical vapour deposition, including by using a simple and fast microwave-assisted intercalation method. Structural and electrochemical studies confirm that the simultaneous conversion and exfoliation of semiconducting 2H-WS2 into nanosheets of its metallic 1T polymorph result in facile electrode kinetics, excellent electrical transport, and proliferation of catalytically active sites.},
    Doi = {10.1039/c4ee01329h},
    ISSN = {1754-5692},
    Keywords = {tungsten disulfide
    mos2 nanosheets
    intercalation
    electrocatalysts
    dichalcogenides
    nanoparticles
    exfoliation
    efficient
    sulfides
    graphene},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000339861800013}
    }
  • [DOI] Mori, T., R. J. Hamers, J. A. Pedersen, and Q. Cui. Integrated Hamiltonian Sampling: A Simple and Versatile Method for Free Energy Simulations and Conformational Sampling. Journal of Physical Chemistry B 2014, 118, 8210-8220.
    [Bibtex]
    @Article{Hamers557,
    Title = {Integrated Hamiltonian Sampling: A Simple and Versatile Method for Free Energy Simulations and Conformational Sampling},
    Author = {Mori, T. and Hamers, R. J. and Pedersen, J. A. and Cui, Q.},
    Journal = {Journal of Physical Chemistry B},
    Year = {2014},
    Note = {ISI Document Delivery No.: AL8DT
    Times Cited: 2
    Cited Reference Count: 95
    Mori, Toshifumi Hamers, Robert J. Pedersen, Joel A. Cui, Qiang
    JSPS; National Science Foundation (NSF) [CHE-1300209]; NSF [OCI-1053575, CHE-0840494]; [NSF-ECS-1152604]
    This work is dedicated to Professor Jim Skinner, a much appreciated and admired colleague, in honor of his numerous contributions to the field of statistical mechanics and his leadership as the director of the Theoretical Chemistry Institute at the University of Wisconsin, Madison. T.M. appreciates the support of the JSPS Postdoctoral Fellowship for Research Abroad. The method development is partially funded by a National Science Foundation (NSF) grant CHE-1300209 to Q.C., and the application to model adsorption on rutile TiO<INF>2</INF> surfaces is supported by NSF-ECS-1152604 to J.A.P. and R.J.H. Computational resources from the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by NSF grant number OCI-1053575, are greatly appreciated; computations are also supported in part by NSF through a major instrumentation grant (CHE-0840494) to the Chemistry department.
    Amer chemical soc
    Washington},
    Number = {28},
    Pages = {8210-8220},
    Volume = {118},
    Abstract = {Motivated by specific applications and the recent work of Gao and co-workers on integrated tempering sampling (ITS), we have developed a novel sampling approach referred to as integrated Hamiltonian sampling (IHS). IHS is straightforward to implement and complementary to existing methods for free energy simulation and enhanced configurational sampling. The method carries out sampling using an effective Hamiltonian constructed by integrating the Boltzmann distributions of a series of Hamiltonians. By judiciously selecting the weights of the different Hamiltonians, one achieves rapid transitions among the energy landscapes that underlie different Hamiltonians and therefore an efficient sampling of important regions of the conformational space. Along this line, IHS shares similar motivations as the enveloping distribution sampling (EDS) approach of van Gunsteren and co-workers, although the ways that distributions of different Hamiltonians are integrated are rather different in IHS and EDS. Specifically, we report efficient ways for determining the weights using a combination of histogram flattening and weighted histogram analysis approaches, which make it straightforward to include many end-state and intermediate Hamiltonians in IHS so as to enhance its flexibility. Using several relatively simple condensed phase examples, we illustrate the implementation and application of IHS as well as potential developments for the near future. The relation of IHS to several related sampling methods such as Hamiltonian replica exchange molecular dynamics and A-dynamics is also briefly discussed.},
    Doi = {10.1021/jp501339t},
    ISSN = {1520-6106},
    Keywords = {replica-exchange method
    molecular-dynamics simulations
    binding
    free-energy
    ligand-binding
    biomolecular systems
    liquid water
    potential functions
    biological-systems
    single simulation
    lambda-dynamics},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000339368800058}
    }
  • [DOI] Putans, B. A., L. M. Bishop, and R. J. Hamers. Versatile Approach to Formation of Light-Harvesting Complexes on Nanostructured Metal Oxide Surfaces via "On-Surface" Assembly. Chemistry of Materials 2014, 26, 3651-3659.
    [Bibtex]
    @Article{Hamers558,
    Title = {Versatile Approach to Formation of Light-Harvesting Complexes on Nanostructured Metal Oxide Surfaces via "On-Surface" Assembly},
    Author = {Putans, B. A. and Bishop, L. M. and Hamers, R. J.},
    Journal = {Chemistry of Materials},
    Year = {2014},
    Note = {ISI Document Delivery No.: AK0FY
    Times Cited: 1
    Cited Reference Count: 45
    Putans, Becca A. Bishop, Lee M. Hamers, Robert J.
    U.S. Department of Energy, Offices of Basic Energy Sciences [DE-FG02-09ER16122]
    This work was supported by the U.S. Department of Energy, Offices of Basic Energy Sciences Grant #DE-FG02-09ER16122.
    Amer chemical soc
    Washington},
    Number = {12},
    Pages = {3651-3659},
    Volume = {26},
    Abstract = {A versatile, two-step "on-surface" assembly method is demonstrated to build heteroleptic light-harvesting complexes on nanostructured metal oxide surfaces. In this process, building-block ligands were first attached to SnO2 surfaces by grafting 2,2'-bipyridine molecules that were modified at the (4,4') positions with surface-reactive binding groups. The surface-bound bipyridine ligands then served as a basis for "on-surface" assembly of complete surface-bound Ru(bpy)(3) complexes by immersing the bipyridyl-modified samples in a solution containing the complex [Ru(bpy)(2)(CH3CN)(2)](PF6)(2) and illuminating with ultraviolet light, which removes the photolabile acetonitrile ligands and allows the solution-phase complex to react with the surface-bound bipyridine molecules to form complete surface-bound Ru(bpy)(3) complexes. We demonstrate that this process is effective using three different surface attachment schemes based on aryl-iodo, benzyl-iodo, and dithione bipyridine derivatives. The stability of the complexes in water and the charge transfer characteristics were then measured for the different ligand attachment methods. The benzyl-iodo complex provides the best surface coverage and greatest stability. We also demonstrated that the building-block ligand can act as a site for regeneration of the complexes on the surface.},
    Doi = {10.1021/m500511d},
    ISSN = {0897-4756},
    Keywords = {sensitized solar-cells
    ruthenium complexes
    chemi-luminescence
    ligand-exchange
    excited-states
    tio2 surfaces
    dynamics
    adsorption
    monolayers
    efficiency},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000338089500012}
    }
  • [DOI] Ding, Q., F. Meng, C. R. English, M. Caban-Acevedo, M. J. Shearer, D. Liang, A. S. Daniel, R. J. Hamers, and S. Jin. Efficient Photoelectrochemical Hydrogen Generation Using Heterostructures of Si and Chemically Exfoliated Metallic MoS2. Journal of the American Chemical Society 2014, 136, 8504-8507.
    [Bibtex]
    @Article{Hamers559,
    Title = {Efficient Photoelectrochemical Hydrogen Generation Using Heterostructures of Si and Chemically Exfoliated Metallic MoS2},
    Author = {Ding, Q. and Meng, F. and English, C. R. and Caban-Acevedo, M. and Shearer, M. J. and Liang, D. and Daniel, A. S. and Hamers, R. J. and Jin, S.},
    Journal = {Journal of the American Chemical Society},
    Year = {2014},
    Note = {ISI Document Delivery No.: AJ5KD
    Times Cited: 35
    Cited Reference Count: 41
    Ding, Qi Meng, Fei English, Caroline R. Caban-Acevedo, Miguel Shearer, Melinda J. Liang, Dong Daniel, Andrew S. Hamers, Robert J. Jin, Song
    U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering [DE-FG02-09ER46664]; Research Corporation Scialog Award; UW-Madison H. I. Romnes Faculty Fellowship; NSF Graduate Research Fellowship
    This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Award DE-FG02-09ER46664. S.J. also thanks Research Corporation Scialog Award and the UW-Madison H. I. Romnes Faculty Fellowship for support. M.C. thanks the NSF Graduate Research Fellowship for support. We thank Donghyeon Kang and Prof. Kyoung-Shin Choi for assistance with GC.
    Amer chemical soc
    Washington},
    Number = {24},
    Pages = {8504-8507},
    Volume = {136},
    Abstract = {We report the preparation and characterization of highly efficient and robust photocathodes based on heterostructures of chemically exfoliated metallic 1T-MoS2 and planar p-type Si for solar-driven hydrogen production. Photocurrents up to 17.6 mA/cm(2) at 0 V vs reversible hydrogen electrode were achieved under simulated 1 sun irradiation, and excellent stability was demonstrated over long-term operation. Electrochemical impedance spectroscopy revealed low charge-transfer resistances at the semiconductor/catalyst and catalyst/electrolyte interfaces, and surface photoresponse measurements also demonstrated slow carrier recombination dynamics and consequently efficient charge carrier separation, providing further evidence for the superior performance. Our results suggest that chemically exfoliated 1T-MoS2/Si heterostructures are promising earth-abundant alternatives to photocathodes based on noble metal catalysts for solar-driven hydrogen production.},
    Doi = {10.1021/ja5025673},
    ISSN = {0002-7863},
    Keywords = {evolution reaction
    silicon photocathode
    array photocathodes
    nanosheets
    electrocatalysts
    catalysts
    photovoltage
    electrodes
    conversion
    graphene},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000337720200005}
    }
  • [DOI] Bozich, J. S., S. E. Lohse, M. D. Torelli, C. J. Murphy, R. J. Hamers, and R. D. Klaper. Surface chemistry, charge and ligand type impact the toxicity of gold nanoparticles to Daphnia magna. Environmental Science-Nano 2014, 1, 260-270.
    [Bibtex]
    @Article{Hamers560,
    Title = {Surface chemistry, charge and ligand type impact the toxicity of gold nanoparticles to Daphnia magna},
    Author = {Bozich, J. S. and Lohse, S. E. and Torelli, M. D. and Murphy, C. J. and Hamers, R. J. and Klaper, R. D.},
    Journal = {Environmental Science-Nano},
    Year = {2014},
    Note = {ISI Document Delivery No.: AZ1AL
    Times Cited: 7
    Cited Reference Count: 78
    Bozich, Jared S. Lohse, Samuel E. Torelli, Marco D. Murphy, Catherine J. Hamers, Robert J. Klaper, Rebecca D.
    National Science Foundation Center for Chemical Innovations grant: Center for Sustainable Nanotechnology [CHE-1240151]
    This work was funded by the National Science Foundation Center for Chemical Innovations grant CHE-1240151: Center for Sustainable Nanotechnology to R. Hamers, R. Klaper, and C. Murphy.
    Royal soc chemistry
    Cambridge},
    Number = {3},
    Pages = {260-270},
    Volume = {1},
    Abstract = {Nanoparticles (NPs) are the basis of a range of emerging technologies used for a variety of industrial, biomedical, and environmental applications. As manufactured NP production increases, so too does the concern about their release into the environment and potentially harmful effects. Creating nanomaterials that have minimal negative environmental impact will heavily influence the sustainability of nanomaterials as a technology. In order to create such NPs, the mechanisms that govern NP toxicity need to be better elucidated. One aspect of NP structure that may influence toxicity is the identity and charge of ligand molecules used to functionalize the NP surface. These surface chemistries have the potential to increase or decrease negative biological impacts, yet their impacts are poorly understood. In this study, the toxicity of three types of functionalized similar to 4-5 nm gold NPs (AuNPs), polyallylamine hydrochloride (PAH-AuNPs), citrate (Cit-AuNPs) and mercaptopropionic acid (MPA-AuNPs) as well as cetyltrimethylammonium bromide-functionalized gold nanorods (CTAB-AuNRs) were evaluated in the toxicological model species, Daphnia magna. In order to get the most detailed information on NP toxicity in D. magna, both acute and chronic toxicity assays were performed. Acute exposure toxicity assays show that overall the negativelycharged AuNPs tested are orders of magnitude less toxic than the positively-charged AuNPs. However, chronic exposure assays show that both positively and negatively-charged particles impact reproduction but potentially through different mechanisms and dependent upon functional group. In addition, while select ligands used in NP functionalization (such as CTAB) that are toxic on their own can contribute to observed NP toxicity, our acute toxicity assays indicate that minimally toxic ligands (such as PAH) can also cause significant toxicity when conjugated to NPs. This research demonstrates that surface chemistry plays a pivotal role in NP toxicity and that surface chemistry has the potential to affect the sustainability of these materials.},
    Doi = {10.1039/c4en00006d},
    ISSN = {2051-8153},
    Keywords = {cellular uptake
    particle-size
    electron-microscopy
    aquatic organisms
    colloidal gold
    functionalization
    nanorods
    growth
    nanomaterials
    cytotoxicity},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000347972700006}
    }
  • [DOI] Szunerits, S., C. E. Nebel, and R. J. Hamers. Surface functionalization and biological applications of CVD diamond. Mrs Bulletin 2014, 39, 517-524.
    [Bibtex]
    @Article{Hamers561,
    Title = {Surface functionalization and biological applications of CVD diamond},
    Author = {Szunerits, S. and Nebel, C. E. and Hamers, R. J.},
    Journal = {Mrs Bulletin},
    Year = {2014},
    Note = {ISI Document Delivery No.: AJ0HN
    Times Cited: 5
    Cited Reference Count: 61
    Szunerits, Sabine Nebel, Christoph E. Hamers, Robert J.
    European Union; Centre National de Recherche Scientifique (CNRS); Universite Lille 1; Nord Pas de Calais region
    This work is funded, in part, by the European Union through a FP7-PEOPLE-IRSES (PHOTORELEASE) and FP7-PEOPLE-ITN (MATCON) grant, the Centre National de Recherche Scientifique (CNRS), the Universite Lille 1, and the Nord Pas de Calais region. S.S. especially wants to thank colleagues, students, and post-docs involved in the work discussed, in particular Rabah Boukherroub, Yannick Coffinier, Alexander Barras, Wang Qi, Palaniappan Subramanian, Manakamana Khanal, Paolo Actis, Ken Haenen, Alexander Kromka, Nathalie Simon, Aloysius Siriwardena, and Jean Dubuission.
    Cambridge univ press
    New york},
    Number = {6},
    Pages = {517-524},
    Volume = {39},
    Abstract = {Recent advances in biotechnology have fueled a need for well-defined, highly stable interfaces modified with a variety of biomolecules. Diamond is a particularly attractive material for biological applications because of its chemical stability and good biocompatibility. Since diamond can be made conductive by doping, it is also of interest for a variety of electrically based biological sensing applications that achieve improved performance through selective biological modification. Recent developments of diamond growth by chemical vapor deposition have enabled the preparation of large-area synthetic diamond films on different substrates at a reasonable cost. An as-grown diamond film is terminated by hydrogen on the surface and shows hydrophobic wetting characteristics, besides chemical inertness. This has created problems for attachment of many biomolecules that are inherently hydrophilic. The challenge to make diamond useful for in vivo applications thus lies in covalently linking biomolecules to such surfaces. Several breakthroughs have been accomplished over the last decade, and attaching biomolecules to diamond in a controlled and reproducible way can nowadays be achieved in several different manners and is the focus of this article.},
    Doi = {10.1557/mrs.2014.99},
    ISSN = {0883-7694},
    Keywords = {boron-doped diamond
    thin-films
    electrochemical detection
    nickel
    nanoparticles
    direct amination
    dna
    nanowires
    immobilization
    strategies
    monolayers},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000337331500015}
    }
  • [DOI] Christianson, J. R., D. Zhu, R. J. Hamers, and J. R. Schmidt. Mechanism of N-2 Reduction to NH3 by Aqueous Solvated Electrons. Journal of Physical Chemistry B 2014, 118, 195-203.
    [Bibtex]
    @Article{Hamers562,
    Title = {Mechanism of N-2 Reduction to NH3 by Aqueous Solvated Electrons},
    Author = {Christianson, J. R. and Zhu, D. and Hamers, R. J. and Schmidt, J. R.},
    Journal = {Journal of Physical Chemistry B},
    Year = {2014},
    Note = {ISI Document Delivery No.: 289JJ
    Times Cited: 2
    Cited Reference Count: 78
    Christianson, Jeffrey R. Zhu, Di Hamers, Robert J. Schmidt, J. R.
    University of Wisconsin Materials Research Science and Engineering Center [DMR-1121288]; National Science Foundation [DMR-1207281, CHE-0840494]
    The computational studies reported here were partially supported by the University of Wisconsin Materials Research Science and Engineering Center under Award DMR-1121288 (J.R.C.). Experimental studies of N<INF>2</INF> reduction were supported by the National Science Foundation under Award DMR-1207281 (D.Z.). Computational resources were utilized from the Center for High Throughput Computing (CHTC)<SUP>77</SUP> and by National Science Foundation Grant CHE-0840494. J.R.S. is an Alfred P. Sloan Research Fellow. The authors also thank Prof. Gil Nathanson for many helpful discussions.
    Amer chemical soc
    Washington},
    Number = {1},
    Pages = {195-203},
    Volume = {118},
    Abstract = {Recently a novel approach to the photocatalytic reduction of molecular nitrogen under ambient conditions was reported in which hydrated electrons generated from ultraviolet illumination of diamond served as the reducing agent [Zhu, D.; Zhang, L.; Ruther, R. E.; Hamers, R J. Photo-Illuminated Diamond as a Solid-State Source of Solvated Electrons in Water for Nitrogen Reduction. Nat. Mater. 2013, 12, 836-841]. This surprising reduction of N-2 by aqueous solvated electrons is absent from the vast existing radiolysis literature and thus has little mechanistic precedent. In this work, a combination of experimental and computational approaches is used to elucidate the detailed molecular-level mechanistic pathway from nitrogen to ammonia. A variety of approaches, including electronic structure calculations, molecular dynamics simulations, kinetic modeling, and pH-dependent experimental measures of NH3 and competing H-2 production, implicate a hydrogen atom addition mechanism at early reduction steps and sequential protonation/direct reduction by a solvated electron at later steps, thus involving both direct and indirect reactions with solvated electrons. This work provides a framework for understanding the possible application of solvated electrons as energetic reducing agents for chemically inert species under mild conditions.},
    Doi = {10.1021/jp406535p},
    ISSN = {1520-6106},
    Keywords = {hydrogen-iodine reaction
    nitrogen-fixation
    atmospheric-pressure
    hydrated electron
    carbon-dioxide
    rate constants
    photocatalytic
    reduction
    ammonia-synthesis
    room-temperature
    water},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000329678000021}
    }
  • [DOI] Hamers, R. J., J. A. Bandy, D. Zhu, and L. Zhang. Photoemission from diamond films and substrates into water: dynamics of solvated electrons and implications for diamond photoelectrochemistry. Faraday Discussions 2014, 172, 397-411.
    [Bibtex]
    @Article{Hamers563,
    Title = {Photoemission from diamond films and substrates into water: dynamics of solvated electrons and implications for diamond photoelectrochemistry},
    Author = {Hamers, R. J. and Bandy, J. A. and Zhu, D. and Zhang, L.},
    Journal = {Faraday Discussions},
    Year = {2014},
    Note = {ISI Document Delivery No.: AU4JZ
    Times Cited: 1
    Cited Reference Count: 38
    Hamers, R. J. Bandy, J. A. Zhu, D. Zhang, L.
    National Science Foundation Solid State and Materials Chemistry Program [DMR-1207281]; Air Force Office of Scientific Research under AFOSR Award [FA9550-12-1-0063]
    Studies of diamond thin film growth, diamond photoemission into aqueous media, and the resulting solvated electron dynamics were supported by the National Science Foundation Solid State and Materials Chemistry Program, Grant DMR-1207281. Studies of diamond-based CO<INF>2</INF> reduction were supported in part by the Air Force Office of Scientific Research under AFOSR Award FA9550-12-1-0063.
    Royal soc chemistry
    Cambridge},
    Pages = {397-411},
    Volume = {172},
    Abstract = {Illumination of diamond with above-bandgap light results in emission of electrons into water and formation of solvated electrons. Here we characterize the materials factors that affect that dynamics of the solvated electrons produced by illumination of niobium substrates and of diamond thin films grown on niobium substrates using transient absorption spectroscopy, and we relate the solvated electron dynamics to the ability to reduce N-2 to NH3. For diamond films grown on niobium substrates for different lengths of time, the initial yield of electrons is similar for the different samples, but the lifetime of the solvated electrons increases approximately 10-fold as the film grows. The time-averaged solvated electron concentration and the yield of NH3 produced from N-2 both show maxima for films grown for 1-2 hours, with thicknesses of 100-200 nm. Measurements at different values of pH on boron-doped diamond films show that the instantaneous electron emission is nearly independent of pH, but the solvated electron lifetime becomes longer as the pH is increased from pH = 2 to pH = 5. Finally, we also illustrate an important caveat arising from the fact that charge neutrality requires that light-induced emission of electrons from diamond must be accompanied by corresponding oxidation reactions. In situations where the valence band holes cannot readily induce solution-phase oxidation reactions, the diamond itself can be etched by reacting with water to produce CO. Implications for other reactions such as photocatalytic CO2 reduction are discussed, along with strategies for mitigating the potential photo-etching phenomena.},
    Doi = {10.1039/c4fd00039k},
    ISSN = {1359-6640},
    Keywords = {oriented pyrolytic-graphite
    sulfuric-acid-solution
    electrochemical
    oxidation
    nanocrystalline diamond
    semiconductor diamond
    photocurrent
    kinetics
    nanoelectrode arrays
    thin-films
    emission
    affinity},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000345578300022}
    }
  • [DOI] Gunsolus, I. L., D. H. Hu, C. Mihai, S. E. Lohse, C. S. Lee, M. D. Torelli, R. J. Hamers, C. J. Murhpy, G. Orr, and C. L. Haynes. Facile method to stain the bacterial cell surface for super-resolution fluorescence microscopy. Analyst 2014, 139, 3174-3178.
    [Bibtex]
    @Article{Hamers564,
    Title = {Facile method to stain the bacterial cell surface for super-resolution fluorescence microscopy},
    Author = {Gunsolus, I. L. and Hu, D. H. and Mihai, C. and Lohse, S. E. and Lee, C. S. and Torelli, M. D. and Hamers, R. J. and Murhpy, C. J. and Orr, G. and Haynes, C. L.},
    Journal = {Analyst},
    Year = {2014},
    Note = {ISI Document Delivery No.: AI3CZ
    Times Cited: 1
    Cited Reference Count: 22
    Gunsolus, Ian L. Hu, Dehong Mihai, Cosmin Lohse, Samuel E. Lee, Chang-soo Torelli, Marco D. Hamers, Robert J. Murhpy, Catherine J. Orr, Galya Haynes, Christy L.
    National Science Foundation [CHE-1240151]; NIEHS [1RC2ES018786-01]; University of Minnesota Biotechnology Institute; Department of Energy's Office of Biological and Environmental Research and located at PNNL
    This work was funded by a grant from the National Science Foundation to the Center for Sustainable Nanotechnology, CHE-1240151. Galya Orr acknowledges partial support from NIEHS grant 1RC2ES018786-01. I. L. G. acknowledges partial support from a training grant from the University of Minnesota Biotechnology Institute. We wish to thank the Jeff Gralnick lab at the University of Minnesota for their donation of Shewanella oneidensis MR-1. A portion of the research was performed at EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at PNNL. CSL acknowledges the Bionanotechnology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahangno, Yuseong-gu, Daejeon 305-806, Korea.
    Royal soc chemistry
    Cambridge},
    Number = {12},
    Pages = {3174-3178},
    Volume = {139},
    Abstract = {A method to fluorescently stain the surfaces of both Gram-negative and Gram-positive bacterial cells compatible with super-resolution fluorescence microscopy is presented. This method utilizes a commercially-available fluorescent probe to label primary amines at the surface of the cell. We demonstrate efficient staining of two bacterial strains, the Gram-negative Shewanella oneidensis MR-1 and the Gram-positive Bacillus subtilis 168. Using structured illumination microscopy and stochastic optical reconstruction microscopy, which require high quantum yield or specialized dyes, we show that this staining method may be used to resolve the bacterial cell surface with sub-diffraction-limited resolution. We further use this method to identify localization patterns of nanomaterials, specifically cadmium selenide quantum dots, following interaction with bacterial cells.},
    Doi = {10.1039/c4an00574k},
    ISSN = {0003-2654},
    Keywords = {optical reconstruction microscopy
    localization analysis
    escherichia-coli
    nanoparticles
    probes
    limit},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000336737900032}
    }
  • [DOI] Kim, M. S., K. M. Louis, J. A. Pedersen, R. J. Hamers, R. E. Peterson, and W. Heideman. Using citrate-functionalized TiO2 nanoparticles to study the effect of particle size on zebrafish embryo toxicity. Analyst 2014, 139, 964-972.
    [Bibtex]
    @Article{Hamers565,
    Title = {Using citrate-functionalized TiO2 nanoparticles to study the effect of particle size on zebrafish embryo toxicity},
    Author = {Kim, M. S. and Louis, K. M. and Pedersen, J. A. and Hamers, R. J. and Peterson, R. E. and Heideman, W.},
    Journal = {Analyst},
    Year = {2014},
    Note = {ISI Document Delivery No.: AA0II
    Times Cited: 5
    Cited Reference Count: 28
    Kim, M. -S. Louis, K. M. Pedersen, J. A. Hamers, R. J. Peterson, R. E. Heideman, W.
    Nanoscale Science and Engineering Center (NSEC); National Science Foundation (NSF) [DMR-0832760]
    We thank Dorothy Nesbit for maintaining lines and for help with zebrafish husbandry, and Ofek Bar-Ilan for helpful discussions. This study was supported by Nanoscale Science and Engineering Center (NSEC) funded by the National Science Foundation (NSF) (DMR-0832760).
    Royal soc chemistry
    Cambridge},
    Number = {5},
    Pages = {964-972},
    Volume = {139},
    Abstract = {TiO2 nanoparticles (NPs) are photoactive, potentially producing toxicity in vivo in the presence of sunlight. We have previously demonstrated photodependent toxicity in zebrafish embryos exposed to TiO2 NPs. Here we investigate the effect of particle size on developing zebrafish exposed to 6, 12 and 15 nm citrate-functionalized anatase TiO2 NPs under either simulated sunlight illumination or in the dark. All three sizes of TiO2 NPs caused photo-dependent toxicity. Under simulated sunlight illumination, the acute toxicity of the 6 nm citrate-TiO2 NPs (120 h LC50 of 23.4 mg L-1) exceeded that of the 12 and 15 nm citrate-TiO2 NPs. Exposure to 6 nm particles under illumination also caused a higher incidence of developmental defects than the larger particles. These abnormalities included pericardial edema, yolksac edema, craniofacial malformation, and opaque yolk. To gain insight into the mechanisms of toxicity, we measured hydroxyl radicals ((OH)-O-center dot) generated by NPs in vitro and reactive oxygen species (ROS) produced in vivo. We found that on a mass basis, smaller particles generated higher levels of ROS both in vitro and in vivo, and the 6 nm citrate-TiO2 NPs induced more oxidative stress than larger particles in the zebrafish embryo. We examined oxidative DNA damage by measuring 8-hydroxydeoxyguanosine in zebrafish exposed to different-sized citrate-TiO2 NPs and found that 6 nm particles caused more DNA damage than did larger particles (12 and 15 nm) under illumination. Our results indicate a photodependent toxicity of citrate-TiO2 NPs to zebrafish embryos, with an inverse relationship between particle size and toxicity. Production of more ROS, resulting in more oxidative stress and more DNA damage, represents one possible mechanism of the higher toxicity of smaller citrate-TiO2 NPs. These results highlight the relationship between citrate-TiO2 NP size and toxicity/oxidative stress in developing zebrafish embryos.},
    Doi = {10.1039/c3an01966g},
    ISSN = {0003-2654},
    Keywords = {titanium-dioxide nanoparticles
    oxidative stress
    nanomaterials
    mechanisms
    reactivity
    system
    acid},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000330778400011}
    }

2013

  • [DOI] Tan, Y. Z., S. Jin, and R. J. Hamers. Photostability of CdSe Quantum Dots Functionalized with Aromatic Dithiocarbamate Ligands. Acs Applied Materials & Interfaces 2013, 5, 12975-12983.
    [Bibtex]
    @Article{Hamers566,
    Title = {Photostability of CdSe Quantum Dots Functionalized with Aromatic Dithiocarbamate Ligands},
    Author = {Tan, Y. Z. and Jin, S. and Hamers, R. J.},
    Journal = {Acs Applied Materials \& Interfaces},
    Year = {2013},
    Note = {ISI Document Delivery No.: 281YR
    Times Cited: 5
    Cited Reference Count: 66
    Tan, Yizheng Jin, Song Hamers, Robert J.
    Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering [DE-FG02-09ER46664]
    We are grateful to Caroline English, Kyle Czech, and Prof. John Wright for helpful discussions and insights. This work was supported by the Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Award DE-FG02-09ER46664.
    Amer chemical soc
    Washington},
    Number = {24},
    Pages = {12975-12983},
    Volume = {5},
    Abstract = {Organic ligands are widely used to enhance the ability of CdSe quantum dots (Qps) to resist photodegradation processes such as photo-oxidation. Because long alkyl chains may adversely affect the performance of QD devices that require fast and efficient charge transfer, shorter aromatic ligands are of increasing interest. In this work, we characterize the formation of phenyl dithiocarbamate (DTC) adducts on CdSe surfaces and the relative effectiveness of different para-substituted phenyl dithiocarbamates to enhance the aqueous photostability of CdSe QDs on TiO2. Optical absorption and photoluminescence measurements show that phenyl DTC ligands can be highly effective at reducing QD photocorrosion in water, and that ligands bearing electron-donating substituents are the most effective. A comparison of the QD photostability resulting from use of ligands bearing DTC versus thiol surface-binding groups shows that the DTC group provides greater QD photostability. Density functional calculations with natural bond order analysis show that the effectiveness of substituted phenyl DTC results from the ability of these ligands to remove positive charge away from the CdSe and to delocalize positive charge on the ligand.},
    Doi = {10.1021/am403744g},
    ISSN = {1944-8244},
    Keywords = {quantum dot
    CdSe
    hole-transfer
    photostability
    photoluminescence
    dithiocarbamate
    surface functionalization
    sensitized solar-cells
    ab-initio calculations
    electrical-properties
    nanocrystal solids
    surface
    photoluminescence
    stability
    exchange
    films
    luminescence},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000329137400028}
    }
  • [DOI] Mori, T., R. J. Hamers, J. A. Pedersen, and Q. Cui. An Explicit Consideration of Desolvation is Critical to Binding Free Energy Calculations of Charged Molecules at Ionic Surfaces. Journal of Chemical Theory and Computation 2013, 9, 5059-5069.
    [Bibtex]
    @Article{Hamers567,
    Title = {An Explicit Consideration of Desolvation is Critical to Binding Free Energy Calculations of Charged Molecules at Ionic Surfaces},
    Author = {Mori, T. and Hamers, R. J. and Pedersen, J. A. and Cui, Q.},
    Journal = {Journal of Chemical Theory and Computation},
    Year = {2013},
    Note = {ISI Document Delivery No.: 252WV
    Times Cited: 8
    Cited Reference Count: 75
    Mori, Toshifumi Hamers, Robert J. Pedersen, Joel A. Cui, Qiang
    JSPS; National Science Foundation (NSF) [CHE-0957285]; NSF [OCI-1053575, CHE-0840494]; [NSF-ECS-1152604]
    T.M. appreciates the support of the JSPS Postdoctoral Fellowship for Research Abroad. The initial exploratory work on method development was funded by a National Science Foundation (NSF) grant, CHE-0957285 (2009-2012), to Q.C., and the application to model adsorption on rutile TiO<INF>2</INF> surfaces was supported by NSF-ECS-1152604 to J.A.P. and R.J.H. Computational resources from the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by NSF grant No. OCI-1053575, are greatly appreciated; computations are also supported in part by NSF through a major instrumentation grant (CHE-0840494) to the Chemistry department.
    Amer chemical soc
    Washington},
    Number = {11},
    Pages = {5059-5069},
    Volume = {9},
    Abstract = {Identifying factors that control the strength and specificity of interactions between peptides and nanoparticles is essential for understanding the potential beneficial and deleterious effects of nanoparticles on biological systems. Computer simulations are valuable in this context, although the reliability of such calculations depends on the force field and sampling algorithm, as well as how the binding constant and binding free energy are defined; the latter must be carefully defined with a clear connection to microscopic models based on statistical mechanics. Using the example of formate binding to the rutile titanium dioxide (TiO2) (110) surface, we demonstrate that a reliable description of the binding process requires an explicit consideration of changes in the solvation state of the binding site. Specifically, we carry out metadynamics simulations in which the solvent coordination number of the binding site, s, is introduced as a collective variable in addition to the vertical distance of the adsorbate to the surface (z). The resulting two-dimensional potential of mean force (2D-PMF) clearly shows that explicitly including the local desolvation of the binding site on the TiO2 surface strongly impacts the convergence and result of the binding free energy calculations. Projecting the 2D-PMF into a one-dimensional PMF along either z or s leads to large errors in the free energy barriers. Results from metadynamics simulations are quantitatively supported by independent alchemical free energy simulations, in which the solvation state of the binding site is also carefully considered by explicitly introducing water molecules to the binding site as the adsorbate is decoupled from the system. On the other hand, preliminary committor analysis for the approximate transition state ensemble constructed based on the 2D-PMF suggests that to properly describe the binding/unbinding kinetics, variables beyond s and z, such as those describing the hydrogen bonding pattern of the adsorbate and surface water, need to be included. We expect that the insights and computational methodologies established in this work will be generally applicable to the analysis of binding interactions between highly charged adsorbates and ionic surfaces in solution, such as those implicated in peptide/nanoparticle binding and biomineralization processes.},
    Doi = {10.1021/ct400487e},
    ISSN = {1549-9618},
    Keywords = {computer-simulations
    efficient generation
    aqueous-solutions
    titanium-dioxide
    kinetic pathways
    metal-surfaces
    am1-bcc model
    amino-acids
    ab-initio
    adsorption},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000327044500037}
    }
  • [DOI] Chen, X., M. Usrey, A. Pena-Hueso, R. West, and R. J. Hamers. Thermal and electrochemical stability of organosilicon electrolytes for lithium-ion batteries. Journal of Power Sources 2013, 241, 311-319.
    [Bibtex]
    @Article{Hamers568,
    Title = {Thermal and electrochemical stability of organosilicon electrolytes for lithium-ion batteries},
    Author = {Chen, X. and Usrey, M. and Pena-Hueso, A. and West, R. and Hamers, R. J.},
    Journal = {Journal of Power Sources},
    Year = {2013},
    Note = {ISI Document Delivery No.: 200TL
    Times Cited: 4
    Cited Reference Count: 30
    Chen, Xin Usrey, Monica Pena-Hueso, Adrian West, Robert Hamers, Robert J.
    National Science Foundation Grant SBIR [0724469]
    This work was supported by the National Science Foundation Grant SBIR grant #0724469 to Silatronix, Inc.
    Elsevier science bv
    Amsterdam},
    Pages = {311-319},
    Volume = {241},
    Abstract = {Organosilicon (OS) electrolytes that integrate an ethylene glycol oligomer with a trimethylsilane head group are promising substitutes for commercial carbonate-based electrolytes because of their low flammability and their high electrochemical and thermal stability. To explore the factors that control thermal and electrochemical stability of these compounds, we developed a real-time headspace analysis apparatus with a mass spectrometer to detect the evolution of decomposition products during thermal cycling and during electrochemical measurements. Here we present mass spectroscopy, XPS, and SEM results exploring the thermal stability of [2-[2-(2-Methoxyethoxy)ethoxy]ethoxy]trimethylsilane (1NM3) with LiPF6, and its electrochemical stability against graphite anodes and LiCoO2 cathodes. Our results show that 1NM3 + LiPF6 shows no significant decomposition below 100 degrees C and at potentials below 4.5 V. At higher temperatures and/or potentials, decomposition of LiPF6 induces hydrolysis of 1NM3. Our results show that LiPF6 decomposition is the limiting factor controlling stability of 1NM3 + LiPF6 electrolytes and also provide fundamental insights into the molecular bonds of 1NM3 that are attacked by PF5 and its decomposition products. Full-cell measurements of 1NM3 + LiPF6 + vinyl carbonate show Coulombic efficiencies of >99.6%. These results point the way to new molecular structures that may have even further enhanced electrochemical and thermal stability. (C) 2013 Elsevier B.V. All rights reserved.},
    Doi = {10.1016/j.jpowsour.2013.04.079},
    ISSN = {0378-7753},
    Keywords = {Electrolyte
    Organosilicon
    Lithium-ion battery
    Hydrolysis
    Thermal
    stability
    siloxane-based electrolyte
    lipf6-based electrolytes
    decomposition
    cells
    performance
    chemistry
    mechanism
    lipf6},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000323093700039}
    }
  • [DOI] Himpsel, F. J., P. L. Cook, G. de la Torre, J. M. Garcia-Lastra, R. Gonzalez-Moreno, J. H. Guo, R. J. Hamers, C. X. Kronawitter, P. S. Johnson, J. E. Ortega, D. Pickup, M. E. Ragoussi, C. Rogero, A. Rubio, R. E. Ruther, L. Vayssieres, W. Yang, and I. Zegkinoglou. Design of solar cell materials via soft X-ray spectroscopy. Journal of Electron Spectroscopy and Related Phenomena 2013, 190, 2-11.
    [Bibtex]
    @Article{Hamers569,
    Title = {Design of solar cell materials via soft X-ray spectroscopy},
    Author = {Himpsel, F. J. and Cook, P. L. and de la Torre, G. and Garcia-Lastra, J. M. and Gonzalez-Moreno, R. and Guo, J. H. and Hamers, R. J. and Kronawitter, C. X. and Johnson, P. S. and Ortega, J. E. and Pickup, D. and Ragoussi, M. E. and Rogero, C. and Rubio, A. and Ruther, R. E. and Vayssieres, L. and Yang, W. and Zegkinoglou, I.},
    Journal = {Journal of Electron Spectroscopy and Related Phenomena},
    Year = {2013},
    Note = {ISI Document Delivery No.: 285EQ
    Times Cited: 4
    Cited Reference Count: 47
    Himpsel, F. J. Cook, P. L. de la Torre, G. Garcia-Lastra, J. M. Gonzalez-Moreno, R. Guo, J. -H. Hamers, R. J. Kronawitter, C. X. Johnson, P. S. Ortega, J. E. Pickup, D. Ragoussi, M. -E. Rogero, C. Rubio, A. Ruther, R. E. Vayssieres, L. Yang, W. Zegkinoglou, I.
    NSF [CHE-1026245, DMR-1121288, DMR-0537588, CHE-0613010, CHE-0911543]; DOE [DE-SC0006931, DE-AC02-05CH11231, DE-FG02-01ER45917]; Spanish Ministerio de Economia y Competitividad [MAT2010-21156-C03-01, C03-03, PIB2010US-00652]; Basque Government [IT-257-07]
    This work was supported by the NSF with the awards CHE-1026245, DMR-1121288 (MRSEC), and DMR-0537588 (SRC), by the DOE under the contracts DE-SC0006931, DE-AC02-05CH11231 (ALS), and DE-FG02-01ER45917 (end station), by the Spanish Ministerio de Economia y Competitividad (MAT2010-21156-C03-01, C03-03, and PIB2010US-00652), and by the Basque Government (IT-257-07). RER and RJH acknowledge support from the NSF with grants CHE-0613010 and CHE-0911543.
    Elsevier science bv
    Amsterdam
    Si
    A},
    Pages = {2-11},
    Volume = {190},
    Abstract = {This overview illustrates how spectroscopy with soft X-rays can assist the development of new materials and new designs for solar cells. The starting point is the general layout of a solar cell, which consists of a light absorber sandwiched between an electron donor and an electron acceptor. There are four relevant energy levels that can be measured with a combination of X-ray absorption spectroscopy and photoelectron spectroscopy, as illustrated for an organic dye as absorber attached to a p-doped diamond film as donor. Systematic measurements of organometallic dyes (phthalocyanines and porphyrins) as a function of the metal atom are presented for the metal 2p and N 1s absorption edges. In combination with density functional theory one can discern trends that are useful for tailoring absorber molecules. A customized porphyrin molecule is investigated that combines an absorber with a donor and a linker to an oxide acceptor. The bridge to device fabrication is crossed by correlating spectroscopic features with the photocurrent in hematite photoanodes for water splitting. For speeding up the development of new materials and designs of solar cells a feedback loop between spectroscopy, theory, synthesis and device fabrication is envisioned. (C) 2012 Elsevier B.V. All rights reserved.},
    Doi = {10.1016/j.elspec.2012.10.002},
    ISSN = {0368-2048},
    Keywords = {Solar cell
    Photovoltaics
    X-ray absorption spectroscopy
    Band offset
    Dye molecule
    Diamond
    electronic-structure
    diamond(111)
    phthalocyanine
    absorption
    emission
    surfaces
    hematite
    exciton
    films},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000329376800002}
    }
  • [DOI] Palacios-Lidon, E., D. F. Pickup, P. S. Johnson, R. E. Ruther, R. Tena-Zaera, R. J. Hamers, J. Colchero, F. J. Himpsel, J. E. Ortega, and C. Rogero. Face-Selective Etching of ZnO during Attachment of Dyes. Journal of Physical Chemistry C 2013, 117, 18414-18422.
    [Bibtex]
    @Article{Hamers570,
    Title = {Face-Selective Etching of ZnO during Attachment of Dyes},
    Author = {Palacios-Lidon, E. and Pickup, D. F. and Johnson, P. S. and Ruther, R. E. and Tena-Zaera, R. and Hamers, R. J. and Colchero, J. and Himpsel, F. J. and Ortega, J. E. and Rogero, C.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2013},
    Note = {ISI Document Delivery No.: 296CM
    Times Cited: 2
    Cited Reference Count: 56
    Palacios-Lidon, E. Pickup, D. F. Johnson, P. S. Ruther, R. E. Tena-Zaera, R. Hamers, R. J. Colchero, J. Himpsel, F. J. Ortega, J. E. Rogero, C.
    Spanish Goverment [MAT2010-21156-C03-01, MAT2010-21156-C03-03, MAT2010-21267-C02-01, PIB2010US-00652]; Basque Government [IT-621-13]; Seneca Foundation [15324/PI/10]; CONSOLIDER Program 'Force for Future' [CSD2010-00024]; United States by the NSF [CHE-1026245, DMR-0537588]; MINECO
    We acknowledge funding support from the Spanish Goverment (MAT2010-21156-C03-01, C03-03, MAT2010-21267-C02-01, PIB2010US-00652), the Basque Government (IT-621-13), the Seneca Foundation (15324/PI/10), and the CONSOLIDER Program 'Force for Future' (CSD2010-00024). This work was supported in the United States by the NSF under Awards CHE-1026245 and DMR-0537588 (Synchrotron Radiation Center). R.T.-Z. and E.P.-L. acknowledge support from the Program "Ramon y Cajal" of the MINECO.
    Amer chemical soc
    Washington},
    Number = {36},
    Pages = {18414-18422},
    Volume = {117},
    Abstract = {Scanning force microscopy and near-edge X-ray absorption spectroscopy are used to study the attachment of Protoporphyrin IX dye molecules to the low-index single-crystal faces of ZnO, namely, the polar (000 (1) over bar) face and the nonpolar (10 (1) over bar0) face. We found that surface etching depends on the crystal face for various dye immobilization procedures: whereas the polar (000 (1) over bar) surface remains nearly unaltered, the nonpolar (10 (1) over bar0) surface is strongly etched by acidic solutions; these results demonstrate the selective attachment of dye molecules to ZnO surfaces, showing that the dye attachment is extremely sensitive to both the exposed facet and the immobilization protocol. This could be a factor in the surprisingly poor efficiency observed for ZnO-based dye-sensitized solar cells, especially those using ZnO nanorod arrays.},
    Doi = {10.1021/jp4045447},
    ISSN = {1932-7447},
    Keywords = {sensitized solar-cells
    crystallographic polarity
    conversion
    efficiency
    electronic-structure
    coumarin-dye
    zinc-oxide
    performance
    surface
    zno(0001)
    stabilization},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000330162700016}
    }
  • [DOI] Zhu, D., L. H. Zhang, R. E. Ruther, and R. J. Hamers. Photo-illuminated diamond as a solid-state source of solvated electrons in water for nitrogen reduction. Nature Materials 2013, 12, 836-841.
    [Bibtex]
    @Article{Hamers571,
    Title = {Photo-illuminated diamond as a solid-state source of solvated electrons in water for nitrogen reduction},
    Author = {Zhu, D. and Zhang, L. H. and Ruther, R. E. and Hamers, R. J.},
    Journal = {Nature Materials},
    Year = {2013},
    Note = {ISI Document Delivery No.: 205CE
    Times Cited: 27
    Cited Reference Count: 49
    Zhu, Di Zhang, Linghong Ruther, Rose E. Hamers, Robert J.
    National Science Foundation [DMR-1207281, DMR-1121288]
    The authors acknowledge L. C. Hamers, S. Hogendoorn, B. Putans and N. Becknell for their assistance with early stages of this work. The authors would also like to thank J. R. Schmidt, J. Christianson and G. Nathanson for useful insights into the N<INF>2</INF> reduction mechanisms. This work was supported by the National Science Foundation DMR-1207281. Initial exploratory experiments were obtained through support from National Science Foundation DMR-1121288.
    Nature publishing group
    London},
    Number = {9},
    Pages = {836-841},
    Volume = {12},
    Abstract = {The photocatalytic reduction of N-2 to NH3 is typically hampered by poor binding of N-2 to catalytic materials and by the very high energy of the intermediates involved in this reaction. Solvated electrons directly introduced into the reactant solution can provide an alternative pathway to overcome such limitations. Here we demonstrate that illuminated hydrogen-terminated diamond yields facile electron emission into water, thus inducing reduction of N-2 to NH3 at ambient temperature and pressure. Transient absorption measurements at 632 nm reveal the presence of solvated electrons adjacent to the diamond after photoexcitation. Experiments using inexpensive synthetic diamond samples and diamond powder show that photocatalytic activity is strongly dependent on the surface termination and correlates with the production of solvated electrons. The use of diamond to eject electrons into a reactant liquid represents a new paradigm for photocatalytic reduction, bringing electrons directly to reactants without requiring molecular adsorption to the surface.},
    Doi = {10.1038/nmat3696},
    ISSN = {1476-1122},
    Keywords = {thin-film electrodes
    iron-doped titania
    photocatalytic reduction
    catalytic-reduction
    ammonia-synthesis
    room-temperature
    exciton
    breakup
    affinity
    dinitrogen
    surface},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000323417600021}
    }
  • [DOI] Wiecinski, P. N., K. M. Metz, T. C. K. Heiden, K. M. Louis, A. N. Mangham, R. J. Hamers, W. Heideman, R. E. Peterson, and J. A. Pedersen. Toxicity of Oxidatively Degraded Quantum Dots to Developing Zebrafish (Danio rerio). Environmental Science & Technology 2013, 47, 9132-9139.
    [Bibtex]
    @Article{Hamers572,
    Title = {Toxicity of Oxidatively Degraded Quantum Dots to Developing Zebrafish (Danio rerio)},
    Author = {Wiecinski, P. N. and Metz, K. M. and Heiden, T. C. K. and Louis, K. M. and Mangham, A. N. and Hamers, R. J. and Heideman, W. and Peterson, R. E. and Pedersen, J. A.},
    Journal = {Environmental Science \& Technology},
    Year = {2013},
    Note = {ISI Document Delivery No.: 205VA
    Times Cited: 5
    Cited Reference Count: 55
    Wiecinski, Paige N. Metz, Kevin M. Heiden, Tisha C. King Louis, Kacie M. Mangham, Andrew N. Hamers, Robert J. Heideman, Warren Peterson, Richard E. Pedersen, Joel A.
    National Science Foundation [DMR-0425880, DMR-082760]; National Institute of Environmental Health Sciences [T32ES007015]
    This research was funded by the National Science Foundation (initiated under DMR-0425880 and completed under DMR-082760). T.C.K.H. and P.N.K. were supported by grant number T32ES007015 from the National Institute of Environmental Health Sciences. The article contents are solely the responsibility of the authors and do not represent official views of the sponsors.
    Amer chemical soc
    Washington},
    Number = {16},
    Pages = {9132-9139},
    Volume = {47},
    Abstract = {Once released into the environment, engineered nanoparticles (eNPs) are subjected to processes that may alter their physical or chemical properties, potentially altering their toxicity vis-a-vis the as-synthesized materials. We examined the toxicity to zebrafish (Danio rerio) embryos of CdSecore/ZnSshell quantum dots (QDs) before and after exposure to an in vitro chemical model designed to simulate oxidative weathering in soil environments based on a reductant-driven Fenton's reaction. Exposure to these oxidative conditions resulted in severe degradation of the QDs: the Zn shell eroded, Cd2+ and selenium were released, and amorphous Se-containing aggregates were formed. Products of QD weathering exhibited higher potency than did as-synthesized QDs. Morphological endpoints of toxicity included pericardial, ocular and yolk sac edema, nondepleted yolk, spinal curvature, tail malformations, and craniofacial malformations. To better understand the selenium-like toxicity observed in QD exposures, we examined the toxicity of selenite, selenate, and amorphous selenium nanoparticles (SeNPs). Selenite exposures resulted in high mortality to embryos/larvae while selenate and SeNPs were nontoxic. Co-exposures to SeNPs + CdCl2 resulted in dramatic increase in mortality and recapitulated the morphological endpoints of toxicity observed with exposure to products of QD weathering. Cadmium body burden was increased in larvae exposed to weathered QDs or SeNP + CdCl2 suggesting the increased potency of products of QD weathering was due to selenium modulation of cadmium toxicity. Our findings highlight the need to examine the toxicity of eNPs after they have undergone environmental weathering processes.},
    Doi = {10.1021/es304987r},
    ISSN = {0013-936X},
    Keywords = {titanium-dioxide nanoparticles
    basidiomycete gloeophyllum-trabeum
    developmental toxicity
    embryonic zebrafish
    selenium toxicity
    humic-acid
    in-vitro
    nanomaterials
    transformation
    exposure},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000323471700018}
    }
  • [DOI] Yang, S. P., O. Bar-Ilan, R. E. Peterson, W. Heideman, R. J. Hamers, and J. A. Pedersen. Influence of Humic Acid on Titanium Dioxide Nanoparticle Toxicity to Developing Zebrafish. Environmental Science & Technology 2013, 47, 4718-4725.
    [Bibtex]
    @Article{Hamers573,
    Title = {Influence of Humic Acid on Titanium Dioxide Nanoparticle Toxicity to Developing Zebrafish},
    Author = {Yang, S. P. and Bar-Ilan, O. and Peterson, R. E. and Heideman, W. and Hamers, R. J. and Pedersen, J. A.},
    Journal = {Environmental Science \& Technology},
    Year = {2013},
    Note = {ISI Document Delivery No.: 141WA
    Times Cited: 27
    Cited Reference Count: 58
    Yang, Sarah P. Bar-Ilan, Ofek Peterson, Richard E. Heideman, Warren Hamers, Robert J. Pedersen, Joel A.
    National Science Foundation [DMR-0832760]; U.S. Environmental Protection Agency STAR grant [RD-83386001-0]
    We thank Jackie Bastyr-Cooper for Ti analysis, Michael Konrath for laboratory assistance, Lee Bishop and Joe Yeager for help with HP-SEC, Sanjay Joshi for the metal halide lamp spectrum, Joe Heintz and Ralph Albrecht for the scanning electron microscopy, and Dorothy Nesbitt and undergraduate assistants for zebrafish husbandry. This work was supported by National Science Foundation grant DMR-0832760 and U.S. Environmental Protection Agency STAR grant RD-83386001-0.
    Amer chemical soc
    Washington},
    Number = {9},
    Pages = {4718-4725},
    Volume = {47},
    Abstract = {Titanium dioxide nanoparticle (TiO2NP) suspension stability can be altered by adsorption of dissolved organic matter (DOM). This is expected to impact their environmental fate and bioavailabllity. To date, the influence of DOM on the toxicity of TiO(2)NPs to aquatic vertebrates has not been reported. We examined the impact of Suwannee River humic acid (HA) on the toxicity of TiO(2)NPs to developing zebrafish (Danio rerio) in the dark and under simulated sunlight illumination. Adsorption of HA increased suspension stability and decreased TiO2NP exposure. TiO(2)NPs were more toxic in the presence of HA. In the absence of simulated sunlight, a small but significant increase in lethality was observed in fish exposed to TiO(2)NPs in the presence of HA. Under simulated sunlight illumination, photocatalytic degradation of HA reduced suspension stability. Despite the lower concentrations of Ti associated with fish in the treatments containing HA, under simulated sunlight illumination, median lethal concentrations were lower and oxidative DNA damage was elevated relative to fish exposed to TiO(2)NPs in the absence of HA. This study demonstrates the importance of considering environmental factors (i.e., exposure to sunlight, adsorption of DOM) when assessing the potential risks posed by engineered nanomaterials in the environment.},
    Doi = {10.1021/es3047334},
    ISSN = {0013-936X},
    Keywords = {metal-oxide nanoparticles
    in-vitro
    gene-expression
    danio-rerio
    aquatic environment
    tio2 nanoparticles
    hydroxyl radicals
    oxidative
    stress
    carbon nanotubes
    organic-matter},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000318756000096}
    }
  • [DOI] Bar-Ilan, O., C. C. Chuang, D. J. Schwahn, S. Yang, S. Joshi, J. A. Pedersen, R. J. Hamers, R. E. Peterson, and W. Heideman. TiO2 Nanoparticle Exposure and Illumination during Zebrafish Development: Mortality at Parts per Billion Concentrations. Environmental Science & Technology 2013, 47, 4726-4733.
    [Bibtex]
    @Article{Hamers574,
    Title = {TiO2 Nanoparticle Exposure and Illumination during Zebrafish Development: Mortality at Parts per Billion Concentrations},
    Author = {Bar-Ilan, O. and Chuang, C. C. and Schwahn, D. J. and Yang, S. and Joshi, S. and Pedersen, J. A. and Hamers, R. J. and Peterson, R. E. and Heideman, W.},
    Journal = {Environmental Science \& Technology},
    Year = {2013},
    Note = {ISI Document Delivery No.: 141WA
    Times Cited: 21
    Cited Reference Count: 20
    Bar-Ilan, Ofek Chuang, Connie C. Schwahn, Denise J. Yang, Sarah Joshi, Sanjay Pedersen, Joel A. Hamers, Robert J. Peterson, Richard E. Heideman, Warren
    NSEC (NSF) [DMR-0425880]; EPA Star Program [RD-83386001-0]
    We thank Dorothy Nesbit, Myzoom Yang, Bert Jansch, and B. Hunter for technical assistance, Ben August and Amanda Thomas for TEM support (UW Madison Medical School Imaging Center), Jackie Bastyr-Cooper for ICP-OES support, Ralph Albrecht for his sage advice, and the Heideman/Peterson groups for insightful discussion. This work was funded by NSEC (NSF Grant No. DMR-0425880) and EPA Star Program (RD-83386001-0).
    Amer chemical soc
    Washington},
    Number = {9},
    Pages = {4726-4733},
    Volume = {47},
    Abstract = {Photoactivation of titanium dioxide nanoparticles (TiO(2)NPs) can produce reactive oxygen species (ROS). Over time, this has the potential to produce cumulative cellular damage. To test this, we exposed zebrafish (Danio rerio) to two commercial TiO2NP preparations at concentrations ranging from 0.01 to 10 000 ng/mL over a 23 day period spanning embryogenesis, larval development, and juvenile metamorphosis. Fish were illuminated with a lamp that mimics solar irradiation. TiO2NP exposure produced significant mortality at 1 ng/mL. Toxicity included stunted growth, delayed metamorphosis, malformations, organ pathology, and DNA damage. TiO(2)NPs were found in the gills and gut and elsewhere. The two preparations differed in nominal particle diameter (12.1 +/- 3.7 and 23.3 +/- 9.8 nm) but produced aggregates in the 1 mu m range. Both were taken up in a dose-dependent manner. Illuminated particles produced a time- and dose-dependent increase in 8-hydroxy-2'-deoxyguanosine DNA adducts consistent with cumulative ROS damage. Zebrafish take up TiO(2)NPs from the aqueous environment even at low ng/mL concentrations, and these particles when illuminated in the violet-near UV range produce cumulative toxicity.},
    Doi = {10.1021/es304514r},
    ISSN = {0013-936X},
    Keywords = {titanium-dioxide
    oxidative stress
    damage
    nanomaterials
    environment
    dna},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000318756000097}
    }
  • [DOI] Ruther, R. E., Q. Cui, and R. J. Hamers. Conformational Disorder Enhances Electron Transfer Through Alkyl Monolayers: Ferrocene on Conductive Diamond. Journal of the American Chemical Society 2013, 135, 5751-5761.
    [Bibtex]
    @Article{Hamers575,
    Title = {Conformational Disorder Enhances Electron Transfer Through Alkyl Monolayers: Ferrocene on Conductive Diamond},
    Author = {Ruther, R. E. and Cui, Q. and Hamers, R. J.},
    Journal = {Journal of the American Chemical Society},
    Year = {2013},
    Note = {ISI Document Delivery No.: 129VT
    Times Cited: 13
    Cited Reference Count: 107
    Ruther, Rose E. Cui, Qiang Hamers, Robert J.
    UW-Madison Materials Research Science and Engineering Center, National Science Foundation Grant [DMR-0520527, DMR-1121288]
    This manuscript is based on research supported by the UW-Madison Materials Research Science and Engineering Center, National Science Foundation Grant DMR-0520527 and DMR-1121288.
    Amer chemical soc
    Washington},
    Number = {15},
    Pages = {5751-5761},
    Volume = {135},
    Abstract = {We have investigated the electron-transfer kinetics of ferrocene groups covalently tethered to surfaces of conductive diamond electrodes. Electrochemical measurements show that the rates are only weakly dependent on chain length but are strongly dependent on the surface coverage; these observations are contrary to what is commonly observed for self-assembled monolayers on gold, pointing to important mechanistic differences in electron transfer processes on covalently bonded materials. Molecular dynamics simulations show that dependence on chain length and molecular density can be readily explained in terms of dynamic crowding effects. At low coverage, conformational flexibility of surface-tethered alkyl chains allows the redox-active ferrocene group to dynamically approach the diamond surface, leading to facile electron transfer for all surface molecules. As the coverage is increased, steric crowding causes the average ferrocene-to-surface distance to increase, decreasing the electron transfer rate. Even at the most dense packings, the mismatch between the spacing of surface lattice sites and the optimum alkyl chain density leads to voids and inherent disorder that facilitates electron transfer. These results are significant in the design and optimization of electrocatalytically active surfaces on covalently bonded materials relevant for electro- and photocatalysis.},
    Doi = {10.1021/ja312680p},
    ISSN = {0002-7863},
    Keywords = {self-assembled monolayers
    thin-film electrodes
    modified gold
    electrodes
    transfer kinetics
    click chemistry
    transfer rates
    redox
    centers
    information-storage
    water-oxidation
    structural-characterization},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000317872800039}
    }
  • [DOI] Gerken, J. B., M. L. Rigsby, R. E. Ruther, R. J. Perez-Rodriguez, I. A. Guzei, R. J. Hamers, and S. S. Stahl. Modular Synthesis of Alkyne-Substituted Ruthenium Polypyridyl Complexes Suitable for "Click" Coupling. Inorganic Chemistry 2013, 52, 2796-2798.
    [Bibtex]
    @Article{Hamers576,
    Title = {Modular Synthesis of Alkyne-Substituted Ruthenium Polypyridyl Complexes Suitable for "Click" Coupling},
    Author = {Gerken, J. B. and Rigsby, M. L. and Ruther, R. E. and Perez-Rodriguez, R. J. and Guzei, I. A. and Hamers, R. J. and Stahl, S. S.},
    Journal = {Inorganic Chemistry},
    Year = {2013},
    Note = {ISI Document Delivery No.: 110JW
    Times Cited: 3
    Cited Reference Count: 35
    Gerken, James B. Rigsby, Matthew L. Ruther, Rose E. Perez-Rodriguez, Riviam J. Guzei, Ilia A. Hamers, Robert J. Stahl, Shannon S.
    National Science Foundation (NSF) [CHE-0911543, DMR-0832760, CHE-0802907]; NSF [CHE-8813550, CHE-9629688, CHE-0342998]; National Institutes of Health [1S10RR004981-01]
    Dr. Elizabeth C. Landis provided the XPS data in Figure S5 in the SI. The authors thank Dr. Charles G. Fry and Paul B. White for helpful advice on <SUP>15</SUP>N NMR techniques. This work was supported, in part, by National Science Foundation (NSF) Grants CHE-0911543 (to R.J.H., for functionalization and characterization of the diamond electrodes), DMR-0832760 (REU support for R.J.P.-R), and CHE-0802907 (to S.S.S., for the design and synthesis of the molecular catalysts). NMR facility funding was supported under NSF Grants CHE-8813550, CHE-9629688, and CHE-0342998 and National Institutes of Health Grant 1S10RR004981-01.
    Amer chemical soc
    Washington},
    Number = {6},
    Pages = {2796-2798},
    Volume = {52},
    Abstract = {A modular synthetic method has been developed for the preparation of Ru polypyridyl complexes bearing a terminal alkyne. This method proceeds through a readily accessible intermediate with a silyl-protected alkyne and allows access to a variety of five- and six-coordinate Ru complexes. These complexes can be easily attached to azide-functionalized electrode surfaces with only slight perturbation of the redox properties of the parent complex.},
    Doi = {10.1021/ic302827s},
    ISSN = {0020-1669},
    Keywords = {sensitized solar-cells
    covalent attachment
    conductive diamond
    chemistry
    surfaces
    molecules
    dye
    functionality
    electrodes
    interfaces},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000316439400004}
    }
  • [DOI] Franking, R., L. S. Li, M. A. Lukowski, F. Meng, Y. Z. Tan, R. J. Hamers, and S. Jin. Facile post-growth doping of nanostructured hematite photoanodes for enhanced photoelectrochemical water oxidation. Energy & Environmental Science 2013, 6, 500-512.
    [Bibtex]
    @Article{Hamers577,
    Title = {Facile post-growth doping of nanostructured hematite photoanodes for enhanced photoelectrochemical water oxidation},
    Author = {Franking, R. and Li, L. S. and Lukowski, M. A. and Meng, F. and Tan, Y. Z. and Hamers, R. J. and Jin, S.},
    Journal = {Energy \& Environmental Science},
    Year = {2013},
    Note = {ISI Document Delivery No.: 075NA
    Times Cited: 59
    Cited Reference Count: 74
    Franking, Ryan Li, Linsen Lukowski, Mark A. Meng, Fei Tan, Yizheng Hamers, Robert J. Jin, Song
    U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering [DE-FG02-09ER46664]; NSF grant [DMR-1106184]; Research Corporation SciaLog Award for Solar Energy Conversion
    R.F. carried out the doping experiments and electrochemical measurements and was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-FG02-09ER46664 (to both S.J. and R.J.H.). L.L. developed the synthesis and doping strategy and performed structural characterization of the materials and is supported by a NSF grant DMR-1106184 (to S.J.). M.A.L. and F.M. assisted with the structural characterization of the materials. Y.T. performed the IPCE measurements. S.J. also thanks the Research Corporation SciaLog Award for Solar Energy Conversion for support.
    Royal soc chemistry
    Cambridge},
    Number = {2},
    Pages = {500-512},
    Volume = {6},
    Abstract = {We report a facile approach to perform post-growth doping of hematite (alpha-Fe2O3) nanostructures by depositing titanium (Ti) precursor solution and subsequent annealing in air. Using hematite nanowire photoanodes on fluorine doped tin oxide (FTO) glass substrates as a model system, the doping conditions were carefully optimized and highly photoactive hematite photoanodes were prepared at a more practically acceptable temperature of 650-700 degrees C than the >= 800 degrees C commonly used in previous works. A combination of microstructural characterization, elemental analysis, photoelectrochemical (PEC) measurements, and electrochemical impedance spectroscopy (EIS) analysis were employed to confirm the distribution of Ti atoms in hematite nanostructures and the role of Ti dopants in enhancing the photocurrent of hematite photoanodes. It was found that the Ti-treatment increases the donor concentration of hematite by about 10 fold and facilitates majority carrier transport and collection, which may account for the performance enhancement. Moreover, EIS measurements under illumination and Mott-Schottky analysis clearly showed that Ti dopants interact with the surface trap states of hematite, suggesting that surface passivation may also contribute to the improved PEC performance. This facile post-growth doping method can be applied to other hematite nanostructures such as electrochemically deposited hematite films and expanded to other dopants such as zirconium (Zr).},
    Doi = {10.1039/c2ee23837c},
    ISSN = {1754-5692},
    Keywords = {alpha-fe2o3 thin-films
    electrochemical deposition route
    hydrogen-production
    p-type
    electrical-properties
    iron(iii) oxide
    metal-oxides
    iron-oxide
    electrodes
    si},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000313892400012}
    }
  • [DOI] Johnson, P. S., P. L. Cook, I. Zegkinoglou, J. M. Garcia-Lastra, A. Rubio, R. E. Ruther, R. J. Hamers, and F. J. Himpsel. Electronic structure of Fe- vs. Ru-based dye molecules. Journal of Chemical Physics 2013, 138, .
    [Bibtex]
    @Article{Hamers578,
    Title = {Electronic structure of Fe- vs. Ru-based dye molecules},
    Author = {Johnson, P. S. and Cook, P. L. and Zegkinoglou, I. and Garcia-Lastra, J. M. and Rubio, A. and Ruther, R. E. and Hamers, R. J. and Himpsel, F. J.},
    Journal = {Journal of Chemical Physics},
    Year = {2013},
    Note = {ISI Document Delivery No.: 086YL
    Times Cited: 5
    Cited Reference Count: 58
    Johnson, Phillip S. Cook, Peter L. Zegkinoglou, Ioannis Garcia-Lastra, J. M. Rubio, Angel Ruther, Rose E. Hamers, Robert J. Himpsel, F. J.
    National Science Foundation (NSF) [CHE-1026245, DMR-1121288, DMR-0537588]; (U.S.) Department of Energy (DOE) [DE-FG02-01ER45917, DE-AC02-05CH11231]; University of Wisconsin; European Research Council [267374]; Spanish Grants [FIS2011-65702-C02-01, PIB2010US-00652]; Grupos Consolidados [IT-319-07]; European Commission project CRONOS [280879-2]
    This work was supported by the National Science Foundation (NSF) under Award Nos. CHE-1026245, DMR-1121288 (MRSEC), DMR-0537588 (SRC), and by the (U.S.) Department of Energy (DOE) under Contract Nos. DE-FG02-01ER45917 (end station) and DE-AC02-05CH11231 (ALS). P. L. Cook acknowledges support from the University of Wisconsin System 2012-2013 Applied Research Grant. J. M. Garcia-Lastra and A. Rubio acknowledge financial support from the European Research Council (ERC-2010-AdG-Proposal No. 267374), Spanish Grants (FIS2011-65702-C02-01 and PIB2010US-00652), Grupos Consolidados (IT-319-07), and European Commission project CRONOS (280879-2).
    Amer inst physics
    Melville},
    Number = {4},
    Volume = {138},
    Abstract = {In order to explore whether Ru can be replaced by inexpensive Fe in dye molecules for solar cells, the differences in the electronic structure of Fe-and Ru-based dyes are investigated by X-ray absorption spectroscopy and first-principles calculations. Molecules with the metal in a sixfold, octahedral N cage, such as tris(bipyridines) and tris(phenanthrolines), exhibit a systematic downward shift of the N 1s-to-pi* transition when Ru is replaced by Fe. This shift is explained by an extra transfer of negative charge from the metal to the N ligands in the case of Fe, which reduces the binding energy of the N 1s core level. The C 1s-to-pi* transitions show the opposite trend, with an increase in the transition energy when replacing Ru by Fe. Molecules with the metal in a fourfold, planar N cage (porphyrins) exhibit a more complex behavior due to a subtle competition between the crystal field, axial ligands, and the 2+ vs. 3+ oxidation states. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4788617]},
    Doi = {10.1063/1.4788617},
    ISSN = {0021-9606},
    Keywords = {ray-absorption spectroscopy
    transition-metal-complexes
    sensitized
    solar-cells
    charge-transfer
    excited-states
    dynamics
    ruthenium
    ligand
    phthalocyanine
    edge},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000314725900057}
    }
  • [DOI] Tan, Y., S. Jin, and R. J. Hamers. Influence of Hole-Sequestering Ligands on the Photostability of CdSe Quantum Dots. Journal of Physical Chemistry C 2013, 117, 313-320.
    [Bibtex]
    @Article{Hamers579,
    Title = {Influence of Hole-Sequestering Ligands on the Photostability of CdSe Quantum Dots},
    Author = {Tan, Y. and Jin, S. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2013},
    Note = {ISI Document Delivery No.: 066KW
    Times Cited: 6
    Cited Reference Count: 78
    Tan, Yizheng Jin, Song Hamers, Robert J.
    Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering [DE-FG02-09ER46664]
    We are grateful to Dr. Ryan Franking for his help in the TiO<INF>2</INF> film preparation and to Prof. John Wright for helpful discussions. This work was supported by the Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Award DE-FG02-09ER46664.
    Amer chemical soc
    Washington},
    Number = {1},
    Pages = {313-320},
    Volume = {117},
    Abstract = {Chalcogenide nanocrystals or quantum dots (QDs) such as CdSe and PbSe have great potential as absorbers for QD-sensitized solar cells, but their practical utility is limited by fast degradation when exposed to ambient environments. Here we present results showing that small organic molecules acting as hole-accepting ligands can be very effective in reducing photooxidation of CdSe QDs. The aromatic amine, 4-dimethylaminothiophenol (DMATP), is shown to be especially effective in enhancing stability of CdSe QDs when illuminated in air or in aqueous environments. Using photoluminescence and density functional theory (DFT) calculations, we show that the enhanced stability results from hole transfer from the QD to the ligand and delocalization of the resulting positive charge on the aromatic ring and amino group instead of the sulfur atom that links the molecule to the CdSe.},
    Doi = {10.1021/jp309587k},
    ISSN = {1932-7447},
    Keywords = {sensitized solar-cells
    cadmium selenide nanocrystals
    electron
    injection
    semiconductor nanocrystals
    surface
    spectroscopy
    dye
    recombination
    solids
    cdte},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000313220700043}
    }

2012

  • [DOI] Yao, S. A., R. E. Ruther, L. H. Zhang, R. A. Franking, R. J. Hamers, and J. F. Berry. Covalent Attachment of Catalyst Molecules to Conductive Diamond: CO2 Reduction Using "Smart" Electrodes. Journal of the American Chemical Society 2012, 134, 15632-15635.
    [Bibtex]
    @Article{Hamers1,
    Title = {Covalent Attachment of Catalyst Molecules to Conductive Diamond: CO2 Reduction Using "Smart" Electrodes},
    Author = {Yao, S. A. and Ruther, R. E. and Zhang, L. H. and Franking, R. A. and Hamers, R. J. and Berry, J. F.},
    Journal = {Journal of the American Chemical Society},
    Year = {2012},
    Note = {Yao, Shu A. Ruther, Rose E. Zhang, Linghong Franking, Ryan A. Hamers, Robert J. Berry, John F.},
    Number = {38},
    Pages = {15632-15635},
    Volume = {134},
    Abstract = {We report here covalent attachment of a catalytically active cobalt complex onto boron-doped, p-type conductive diamond. Peripheral acetylene groups were appended on a cobalt porphyrin complex, and azide-alkyne cycloaddition was used for covalent linking to a diamond surface decorated with alkyl azides. The functionalized surface was characterized by X-ray photoelectron spectroscopy and Fourier transform IR spectroscopy, and the catalytic activity was characterized using cyclic voltammetry and FTIR. The catalyst-modified diamond surfaces were used as "smart" electrodes exhibiting good stability and electrocatalytic activity for electrochemical reduction of CO2 to CO in acetonitrile solution.},
    Doi = {10.1021/ja304783j},
    ISSN = {0002-7863},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000309099700005
    http://pubs.acs.org/doi/abs/10.1021/ja304783j}
    }
  • [DOI] Li, L. S., Y. H. Yu, F. Meng, Y. Z. Tan, R. J. Hamers, and S. Jin. Facile Solution Synthesis of alpha-FeF3 center dot 3H(2)O Nanowires and Their Conversion to alpha-Fe2O3 Nanowires for Photoelectrochemical Application. Nano Letters 2012, 12, 724-731.
    [Bibtex]
    @Article{Hamers10,
    Title = {Facile Solution Synthesis of alpha-FeF3 center dot 3H(2)O Nanowires and Their Conversion to alpha-Fe2O3 Nanowires for Photoelectrochemical Application},
    Author = {Li, L. S. and Yu, Y. H. and Meng, F. and Tan, Y. Z. and Hamers, R. J. and Jin, S.},
    Journal = {Nano Letters},
    Year = {2012},
    Note = {Li, Linsen Yu, Yanghai Meng, Fei Tan, Yizheng Hamers, Robert J. Jin, Song},
    Number = {2},
    Pages = {724-731},
    Volume = {12},
    Abstract = {We report for the first time the facile solution growth of alpha-FeF3 center dot 3H(2)O nanowires (NWs) in large quantity at a low supersaturation level and their scalable conversion to porous semiconducting alpha-Fe2O3 (hematite) NWs of high aspect ratio via a simple thermal treatment in air. The structural characterization by transmission electron microscopy shows that thin alpha-FeF3 center dot 3H(2)O NWs (typically < 100 nm in diameter) are converted to single-crystal alpha-Fe2O3 NWs with internal pores, while thick ones (typically > 100 nm in diameter) become polycrystalline porous alpha-Fe2O3 NWs. We further demonstrated the photoelectrochemical (PEC) application of the nanostructured photoelectrodes prepared from these converted hematite NWs. The optimized photoelectrode with similar to 400 nm thick hematite NW film yielded a photocurrent density of 0.54 mA/cm(2) at 1.23 V vs reversible hydrogen electrode potential after modification with cobalt catalyst under standard conditions (AM 1.5 G, 100 mW/cm(2), pH = 13.6, 1 M NaOH). The low cost, large quantity, and high aspect ratio of the converted hematite NWs, together with the resulting simpler photoelectrode preparation, can be of great benefit for hematite-based PEC water splitting. Furthermore, the ease and scalability of the conversion from hydrated fluoride NWs to oxide NWs suggest a potentially versatile and low-cost strategy to make NWs of other useful iron-based compounds that may enable their large-scale renewable energy applications.},
    Doi = {10.1021/nl2036854},
    ISSN = {1530-6984},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000299967800034
    http://pubs.acs.org/doi/abs/10.1021/nl2036854}
    }
  • [DOI] Bishop, L. M., J. C. Yeager, X. Chen, J. N. Wheeler, M. D. Torelli, M. C. Benson, S. D. Burke, J. A. Pedersen, and R. J. Hamers. A Citric Acid-Derived Ligand for Modular Functionalization of Metal Oxide Surfaces via "Click" Chemistry. Langmuir 2012, 28, 1322-1329.
    [Bibtex]
    @Article{Hamers11,
    Title = {A Citric Acid-Derived Ligand for Modular Functionalization of Metal Oxide Surfaces via "Click" Chemistry},
    Author = {Bishop, L. M. and Yeager, J. C. and Chen, X. and Wheeler, J. N. and Torelli, M. D. and Benson, M. C. and Burke, S. D. and Pedersen, J. A. and Hamers, R. J.},
    Journal = {Langmuir},
    Year = {2012},
    Note = {Bishop, Lee M. Yeager, Joseph C. Chen, Xin Wheeler, Jamie N. Torelli, Marco D. Benson, Michelle C. Burke, Steven D. Pedersen, Joel A. Hamers, Robert J.},
    Number = {2},
    Pages = {1322-1329},
    Volume = {28},
    Abstract = {Citric acid is a widely used surface-modifying ligand for growth and processing of a variety of nanoparticles; however, the inability to easily prepare derivatives of this molecule has restricted the development of versatile chemistries for nanoparticle surface functionalization. Here, we report the design and synthesis of a citric acid derivative bearing an alkyne group and demonstrate that this molecule provides the ability to achieve stable, multidentate carboxylate binding to metal oxide nanoparticles, while also enabling subsequent multistep chemistry via the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. The broad utility of this strategy for the modular functionalization of metal oxide surfaces was demonstrated by its application in the CuAAC modification of ZnO, Fe(2)O(3), TiO(2), and WO(3) nanoparticles.},
    Doi = {10.1021/la204145t},
    ISSN = {0743-7463},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000299137800031
    http://pubs.acs.org/doi/abs/10.1021/la204145t}
    }
  • [DOI] Metz, K. M., P. E. Colavita, K. Y. Tse, and R. J. Hamers. Nanotextured gold coatings on carbon nanofiber scaffolds as ultrahigh surface-area electrodes. Journal of Power Sources 2012, 198, 393-401.
    [Bibtex]
    @Article{Hamers12,
    Title = {Nanotextured gold coatings on carbon nanofiber scaffolds as ultrahigh surface-area electrodes},
    Author = {Metz, K. M. and Colavita, P. E. and Tse, K. Y. and Hamers, R. J.},
    Journal = {Journal of Power Sources},
    Year = {2012},
    Note = {Metz, Kevin M. Colavita, Paula E. Tse, Kiu-Yuen Hamers, Robert J.},
    Pages = {393-401},
    Volume = {198},
    Abstract = {High surface area metal electrodes are desirable for applications in energy storage and energy conversion. Here, the formation and electrochemical characterization of a hybrid material made by electroless deposition of gold onto a scaffolding of vertically aligned carbon nanofibers is described. Vertically aligned carbon nanofibers, similar to 80 nm in diameter, provided mechanical support and electrical contact to the highly textured nanoscale gold coatings. By chemically functionalizing the nanofiber surfaces and then using electroless deposition methods, a highly textured metal coating was formed. The electrochemical response of these "nano-on-nano" hybrid electrodes was characterized using electrochemical methods. The results show that using the metallic coatings can increase the electrochemically active surface area by up to a factor of 10 compared with the starting carbon nanofiber scaffolds. The electrochemical response of the electrodes was modulated by varying the deposition time of the gold. (C) 2011 Elsevier B.V. All rights reserved.},
    Doi = {10.1016/j.jpowsour.2011.09.098},
    ISSN = {0378-7753},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000297890700058
    http://www.sciencedirect.com/science/article/pii/S0378775311019343}
    }
  • [DOI] Shah, S., M. C. Benson, L. M. Bishop, A. M. Huhn, R. E. Ruther, J. C. Yeager, Y. Z. Tan, K. M. Louis, and R. J. Hamers. Chemically assembled heterojunctions of SnO2 nanorods with TiO2 nanoparticles via "click" chemistry. Journal of Materials Chemistry 2012, 22, 11561-11567.
    [Bibtex]
    @Article{Hamers13,
    Title = {Chemically assembled heterojunctions of SnO2 nanorods with TiO2 nanoparticles via "click" chemistry},
    Author = {Shah, S. and Benson, M. C. and Bishop, L. M. and Huhn, A. M. and Ruther, R. E. and Yeager, J. C. and Tan, Y. Z. and Louis, K. M. and Hamers, R. J.},
    Journal = {Journal of Materials Chemistry},
    Year = {2012},
    Note = {Shah, Sohil Benson, Michelle C. Bishop, Lee M. Huhn, Alex M. Ruther, Rose E. Yeager, Joseph C. Tan, Yizheng Louis, Kacie M. Hamers, Robert J.},
    Number = {23},
    Pages = {11561-11567},
    Volume = {22},
    Abstract = {SnO2 is a promising material for photovoltaic and photocatalytic applications because it exhibits high electron mobility, its conduction band lies at a convenient energy to act as an electron acceptor, and it can be easily grown in a variety of different nanostructures including nanoparticles, nanorods, and nanosheets. However, strategies for surface functionalization of SnO2 are much less well developed than alternative oxides. Here, we demonstrate the growth and subsequent chemical functionalization of SnO2 nanorods to enable the chemically directed assembly of SnO2 nanorod-TiO2 nanoparticle heterojunctions, and we characterize the charge-transfer properties using time-resolved surface photovoltage measurements. Vertically aligned SnO2 nanorods were grown via a high-pressure chemical synthesis method. The SnO2 nanorods were square in cross-section, exposing sidewalls consisting of {110}-type crystal planes. Functionalization via photochemical grafting with butenol yielded nanorods terminated with a high density of -OH groups that were converted to azide groups. The azide groups were linked with alkyne-modified TiO2 nanoparticles via the Cu(I)-catalyzed Azide-Alkyne Cycloaddition (CuAAC) reaction, a form of "click'' chemistry, thereby covalently grafting the TiO2 nanoparticles to the SnO2 nanorods. Time-resolved surface photovoltage measurements of the resulting adducts showed that the covalent bonding of TiO2 nanoparticles to the SnO2 nanorods enhances the interfacial charge transfer compared to the unmodified SnO2 nanorods, leading to an increased accumulation of holes at the surface.},
    Doi = {10.1039/c2jm31227a},
    ISSN = {0959-9428},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000304351400023
    http://pubs.rsc.org/en/Content/ArticleLanding/2012/JM/c2jm31227a}
    }
  • [DOI] Cardiel, A. C., M. C. Benson, L. M. Bishop, K. M. Louis, J. C. Yeager, Y. Z. Tan, and R. J. Hamers. Chemically Directed Assembly of Photoactive Metal Oxide Nanoparticle Heterojunctions via the Copper-Catalyzed Azide-Alkyne Cycloaddition "Click" Reaction. Acs Nano 2012, 6, 310-318.
    [Bibtex]
    @Article{Hamers14,
    Title = {Chemically Directed Assembly of Photoactive Metal Oxide Nanoparticle Heterojunctions via the Copper-Catalyzed Azide-Alkyne Cycloaddition "Click" Reaction},
    Author = {Cardiel, A. C. and Benson, M. C. and Bishop, L. M. and Louis, K. M. and Yeager, J. C. and Tan, Y. Z. and Hamers, R. J.},
    Journal = {Acs Nano},
    Year = {2012},
    Note = {Cardiel, Allison C. Benson, Michelle C. Bishop, Lee M. Louis, Kacie M. Yeager, Joseph C. Tan, Yizheng Hamers, Robert J.},
    Number = {1},
    Pages = {310-318},
    Volume = {6},
    Abstract = {Metal oxides play a key role in many emerging applications in renewable energy, such as dye-sensitized solar cells and photocatalysts. Because the separation of charge can often be facilitated at junctions between different materials, there is great interest in the formation of heterojunctions between metal oxides. Here, we demonstrate use of the copper-catalyzed azide-alkyne cycloaddition reaction, widely referred to as "click" chemistry, to chemically assemble photoactive heterojunctions between metal oxide nanoparticles, using WO3 and TiO2 as a model system. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy verify the nature and selectivity of the chemical linkages, while scanning electron microscopy reveals that the TiO2 nanoparticles form a high-density, conformal coating on the larger WO3 nanoparticles. Time-resolved surface photoresponse measurements show that the resulting dyadic structures support photoactivated charge transfer, while measurements of the photocatalytic degradation of methylene blue show that chemical grafting of TiO2 nanoparticies to WO3 increases the photocatalytic activity compared with the bare WO3 film.},
    Doi = {10.1021/nn203585r},
    ISSN = {1936-0851},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000299368300040
    http://pubs.acs.org/doi/pdfplus/10.1021/nn203585r}
    }
  • [DOI] Bar-Ilan, O., K. M. Louis, S. P. Yang, J. A. Pedersen, R. J. Hamers, R. E. Peterson, and W. Heideman. Titanium dioxide nanoparticles produce phototoxicity in the developing zebrafish. Nanotoxicology 2012, 6, 670-679.
    [Bibtex]
    @Article{Hamers2,
    Title = {Titanium dioxide nanoparticles produce phototoxicity in the developing zebrafish},
    Author = {Bar-Ilan, O. and Louis, K. M. and Yang, S. P. and Pedersen, J. A. and Hamers, R. J. and Peterson, R. E. and Heideman, W.},
    Journal = {Nanotoxicology},
    Year = {2012},
    Note = {Bar-Ilan, Ofek Louis, Kacie M. Yang, Sarah P. Pedersen, Joel A. Hamers, Robert J. Peterson, Richard E. Heideman, Warren},
    Number = {6},
    Pages = {670-679},
    Volume = {6},
    Abstract = {Exposure of humans and other organisms to nanomaterials is increasing exponentially. It is important, but difficult, to predict the biological consequences of these exposures. We hypothesized that the unique chemical properties that make nanoparticles useful might also be the key in predicting their biological impact. To investigate this, we chose titanium dioxide nanoparticles (TiO(2)NPs) and developing zebrafish embryos as model systems. TiO(2)NPs absorb photons to generate electron-hole pairs that react with water and oxygen to form cytotoxic reactive oxygen species (ROS). Here, we show that the exposure of zebrafish embryos to TiO(2)NPs produces malformation and death, but only if the fish are also illuminated. TiO(2)NPs are taken up into the developing fish, but the egg chorion is a barrier to uptake until the embryos hatch. Chemical probes and a transgenic reporter line confirm photo-dependent production of ROS in vivo, and the addition of an ROS scavenger rescues fish embryos from toxicity. To our knowledge, this is the first study to show a photo-dependent toxic response in a whole organism from exposure to TiO(2)NPs. Of further significance, our study highlights the relationship between the property of the material that makes it useful and the biological effect that is produced. This concept should serve as a guide for future nanotoxicological studies aiming to identify potential hazardous effects on organisms.},
    Doi = {10.3109/17435390.2011.604438},
    ISSN = {1743-5390},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000307227300012
    http://informahealthcare.com/doi/abs/10.3109/17435390.2011.604438}
    }
  • [DOI] Franking, R., H. Kim, S. A. Chambers, A. N. Mangham, and R. J. Hamers. Photochemical Grafting of Organic Alkenes to Single-Crystal TiO2 Surfaces: A Mechanistic Study. Langmuir 2012, 28, 12085-12093.
    [Bibtex]
    @Article{Hamers3,
    Title = {Photochemical Grafting of Organic Alkenes to Single-Crystal TiO2 Surfaces: A Mechanistic Study},
    Author = {Franking, R. and Kim, H. and Chambers, S. A. and Mangham, A. N. and Hamers, R. J.},
    Journal = {Langmuir},
    Year = {2012},
    Note = {Franking, Ryan Kim, Heesuk Chambers, Scott A. Mangham, Andrew N. Hamers, Robert J.},
    Number = {33},
    Pages = {12085-12093},
    Volume = {28},
    Abstract = {The UV-induced photochemical grafting of terminal alkenes has emerged as a versatile way to form molecular layers on semiconductor surfaces. Recent studies have shown that grafting reactions can be initiated by photoelectron emission into the reactant liquid as well as by excitation across the semiconductor band gap, but the relative importance of these two processes is expected to depend on the nature of the semiconductors, the reactant alkene and the excitation wavelength. Here we report a study of the wavelength-dependent photochemical grafting of alkenes onto single-crystal TiO2 samples. Trifluoroacetamide-protected 10-aminododec-1-ene (TFAAD), 10-N-BOC-aminodec-1-ene (t-BOC), and 1-dodecene were used as model alkenes. On rutile (110), photons with energy above the band gap but below the expected work function are not effective at inducing grafting, while photons with energy sufficient to induce electronic transitions from the TiO2 Fermi level to electronic acceptor states of the reactant molecules induce grafting. A comparison of rutile (110), rutile (001), anatase (001), and anatase (101) samples shows slightly enhanced grafting for rutile but no difference between crystal faces for a given crystal phase. Hydroxylation of the surface increases the reaction rate by lowering the work function and thereby facilitating photoelectron ejection into the adjacent alkene. These results demonstrate that photoelectron emission is the dominant mechanism responsible for grafting when using short-wavelength (similar to 254 nm) light and suggest that photoemission events beginning on mid-gap states may play a crucial role.},
    Doi = {10.1021/la302169k},
    ISSN = {0743-7463},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000307695800017
    http://pubs.acs.org/doi/abs/10.1021/la302169k}
    }
  • [DOI] Chen, J. X., R. E. Ruther, Y. Z. Tan, L. M. Bishop, and R. J. Hamers. Molecular Adsorption on ZnO(10(1)over-bar0) Single-Crystal Surfaces: Morphology and Charge Transfer. Langmuir 2012, 28, 10437-10445.
    [Bibtex]
    @Article{Hamers4,
    Title = {Molecular Adsorption on ZnO(10(1)over-bar0) Single-Crystal Surfaces: Morphology and Charge Transfer},
    Author = {Chen, J. X. and Ruther, R. E. and Tan, Y. Z. and Bishop, L. M. and Hamers, R. J.},
    Journal = {Langmuir},
    Year = {2012},
    Note = {Chen, Jixin Ruther, Rose E. Tan, Yizheng Bishop, Lee M. Hamers, Robert J.},
    Number = {28},
    Pages = {10437-10445},
    Volume = {28},
    Abstract = {While ZnO has excellent electrical properties, it has not been widely used for dye-sensitized solar cells, in part because ZnO is chemically less stable than widely used TiO2. The functional groups typically used for surface passivation and for attaching dye molecules either bind weakly or etch the ZnO surface. We have compared the formation of molecular layers from alkane molecules with terminal carboxylic acid, alcohol, amine, phosphonic acid, or thiol functional groups on single-crystal zinc oxide (10 (1) over bar0) surfaces. Atomic force microscopy (AFM) images show that alkyl carboxylic acids etch the surface whereas alkyl amine and alkyl alcohols bind only weakly on the ZnO(10 (1) over bar0) surface. Phosphonic acid-terminated molecules were found to bind to the surface in a heterogeneous manner, forming clusters of molecules. Alkanethiols were found to bind to the surface, forming highly uniform monolayers with some etching detected after long immersion times in an alkanethiol solution. Monolayers of hexadecylphosphonic acid and octadecanethiol were further analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. AFM scratching shows that thiols were bound strongly to the ZnO surface, suggesting the formation of strong Zn-S covalent bonds. Surprisingly, the tridentate phosphonic acids adhered much more weakly than the monodentate thiol. The influence of organic grafting on the Charge transfer to ZnO was studied by time-resolved surface photovoltage measurements and electrochemical impedance measurements. Our results show that the grafting of thiols to ZnO leads to robust surfaces and reduces the surface band bending due to midgap surface states.},
    Doi = {10.1021/la301347t},
    ISSN = {0743-7463},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000306441100016
    http://pubs.acs.org/doi/abs/10.1021/la301347t}
    }
  • [DOI] Zegkinoglou, I., P. L. Cook, P. S. Johnson, W. L. Yang, J. H. Guo, D. Pickup, R. Gonzalez-Moreno, C. Rogero, R. E. Ruther, M. L. Rigsby, J. E. Ortega, R. J. Hamers, and F. J. Himpsel. Electronic Structure of Diamond Surfaces Functionalized by Ru(tpy)(2). Journal of Physical Chemistry C 2012, 116, 13877-13883.
    [Bibtex]
    @Article{Hamers5,
    Title = {Electronic Structure of Diamond Surfaces Functionalized by Ru(tpy)(2)},
    Author = {Zegkinoglou, I. and Cook, P. L. and Johnson, P. S. and Yang, W. L. and Guo, J. H. and Pickup, D. and Gonzalez-Moreno, R. and Rogero, C. and Ruther, R. E. and Rigsby, M. L. and Ortega, J. E. and Hamers, R. J. and Himpsel, F. J.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2012},
    Note = {Zegkinoglou, Ioannis Cook, Peter L. Johnson, Phillip S. Yang, Wanli Guo, Jinghua Pickup, David Gonzalez-Moreno, Ruben Rogero, Celia Ruther, Rose E. Rigsby, Matthew L. Enrique Ortega, J. Hamers, Robert J. Himpsel, F. J.},
    Number = {26},
    Pages = {13877-13883},
    Volume = {116},
    Abstract = {Highly doped diamond films are new candidates for electrodes in reactive environments, such as electrocatalytic interfaces. Here the electronic structure of such films is investigated by X-ray absorption spectroscopy at the C Is and B Is edges, combined with X-ray and ultraviolet photoelectron spectroscopy, as well as optical measurements. A diamond surface functionalized covalently with Ru(tpy)(2), a model complex similar to ruthenium-based molecules used in photocatalysis and photovoltaics, is compared to a hydrogen-terminated diamond surface as a reference. Bulk-sensitive absorption spectra with photon detection reveal diamond gap states, while surface-sensitive spectra with electron detection reveal the adsorbate states and pi-bonding at the diamond surface. The positions of the frontier orbitals of the dye relative to the band edges of diamond are inferred from the spectroscopic data. The implications of using diamond films as inert electron donors in photocatalysis and dye-sensitized solar cells are discussed.},
    Doi = {10.1021/jp304016t},
    ISSN = {1932-7447},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000305933900006
    http://pubs.acs.org/doi/abs/10.1021/jp304016t}
    }
  • [DOI] Szakal, C., J. A. McCarthy, M. S. Ugelow, A. R. Konicek, K. Louis, B. Yezer, A. A. Herzing, R. J. Hamers, and R. D. Holbrook. Preparation and measurement methods for studying nanoparticle aggregate surface chemistry. Journal of Environmental Monitoring 2012, 14, 1914-1925.
    [Bibtex]
    @Article{Hamers580,
    Title = {Preparation and measurement methods for studying nanoparticle aggregate surface chemistry},
    Author = {Szakal, C. and McCarthy, J. A. and Ugelow, M. S. and Konicek, A. R. and Louis, K. and Yezer, B. and Herzing, A. A. and Hamers, R. J. and Holbrook, R. D.},
    Journal = {Journal of Environmental Monitoring},
    Year = {2012},
    Note = {ISI Document Delivery No.: 965VW
    Times Cited: 2
    Cited Reference Count: 25
    Szakal, Christopher McCarthy, James A. Ugelow, Melissa S. Konicek, Andrew R. Louis, Kacie Yezer, Benjamin Herzing, Andrew A. Hamers, Robert J. Holbrook, R. David
    Royal soc chemistry
    Cambridge},
    Number = {7},
    Pages = {1914-1925},
    Volume = {14},
    Abstract = {Despite best efforts at controlling nanoparticle (NP) surface chemistries, the environment surrounding nanomaterials is always changing and can impart a permanent chemical memory. We present a set of preparation and measurement methods to be used as the foundation for studying the surface chemical memory of engineered NP aggregates. We attempt to bridge the gap between controlled lab studies and real-world NP samples, specifically TiO2, by using well-characterized and consistently synthesized NPs, controllably producing NP aggregates with precision drop-on-demand inkjet printing for subsequent chemical measurements, monitoring the physical morphology of the NP aggregate depositions with scanning electron microscopy (SEM), acquiring "surface-to-bulk'' mass spectra of the NP aggregate surfaces with time-of-flight secondary ion mass spectrometry (ToF-SIMS), and developing a data analysis scheme to interpret chemical signatures more accurately from thousands of data files. We present differences in mass spectral peak ratios for bare TiO2 NPs compared to NPs mixed separately with natural organic matter (NOM) or pond water. The results suggest that subtle changes in the local environment can alter the surface chemistry of TiO2 NPs, as monitored by Ti+/TiO+ and Ti+/C3H5+ peak ratios. The subtle changes in the absolute surface chemistry of NP aggregates vs. that of the subsurface are explored. It is envisioned that the methods developed herein can be adapted for monitoring the surface chemistries of a variety of engineered NPs obtained from diverse natural environments.},
    Doi = {10.1039/c2em30048f},
    ISSN = {1464-0325},
    Keywords = {titanium-dioxide nanoparticles
    anatase
    sims
    environment
    stability},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000305796500016}
    }
  • [DOI] Siddiqui, S., Z. T. Dai, C. J. Stavis, H. J. Zeng, N. Moldovan, R. J. Hamers, J. A. Carlisle, and P. U. Arumugam. A quantitative study of detection mechanism of a label-free impedance biosensor using ultrananocrystalline diamond microelectrode array. Biosensors & Bioelectronics 2012, 35, 284-290.
    [Bibtex]
    @Article{Hamers7,
    Title = {A quantitative study of detection mechanism of a label-free impedance biosensor using ultrananocrystalline diamond microelectrode array},
    Author = {Siddiqui, S. and Dai, Z. T. and Stavis, C. J. and Zeng, H. J. and Moldovan, N. and Hamers, R. J. and Carlisle, J. A. and Arumugam, P. U.},
    Journal = {Biosensors \& Bioelectronics},
    Year = {2012},
    Note = {Siddiqui, Shabnam Dai, Zhenting Stavis, Courtney J. Zeng, Hongjun Moldovan, Nicolaie Hamers, Robert J. Carlisle, John A. Arumugam, Prabhu U.},
    Number = {1},
    Pages = {284-290},
    Volume = {35},
    Abstract = {It is well recognized that label-free biosensors are the only class of sensors that can rapidly detect antigens in real-time and provide remote environmental monitoring and point-of-care diagnosis that is low-cost, specific, and sensitive. Electrical impedance spectroscopy (EIS) based label-free biosensors have been used to detect a wide variety of antigens including bacteria, viruses, DNA, and proteins due to the simplicity of their detection technique. However, their commercial development has been hindered due to difficulty in interpreting the change in impedance upon antigen binding and poor signal reproducibility as a result of surface fouling and non-specific binding. In this study, we develop a circuit model to adequately describe the physical changes at bio functionalized surface and provide an understanding of the detection mechanism based on electron exchange between electrolyte and surface through pores surrounding antibody-antigen. The model was successfully applied to extract quantitative information about the bio surface at different stages of surface functionalization. Further, we demonstrate boron-doped ultra-nanocrystalline diamond (UNCD) microelectrode array (3 x 3 format, 200 mu m diameter) improves signal reproducibility significantly and increases sensitivity by four orders of magnitude. This study marks the first demonstration of UNCD array based biosensor that can reliably detect a model Escherichia colt K12 bacterium using EIS, positioning this technology for rapid adoption in point-of-use applications. (C) 2012 Elsevier B.V. All rights reserved.},
    Doi = {10.1016/j.bios.2012.03.001},
    ISSN = {0956-5663},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000305036000043
    http://www.sciencedirect.com/science/article/pii/S095656631200142X}
    }
  • [DOI] English, C. R., L. M. Bishop, J. X. Chen, and R. J. Hamers. Formation of Self-Assembled Monolayers of pi-Conjugated Molecules on TiO2 Surfaces by Thermal Grafting of Aryl and Benzyl Halides. Langmuir 2012, 28, 6866-6876.
    [Bibtex]
    @Article{Hamers8,
    Title = {Formation of Self-Assembled Monolayers of pi-Conjugated Molecules on TiO2 Surfaces by Thermal Grafting of Aryl and Benzyl Halides},
    Author = {English, C. R. and Bishop, L. M. and Chen, J. X. and Hamers, R. J.},
    Journal = {Langmuir},
    Year = {2012},
    Note = {English, Caroline R. Bishop, Lee M. Chen, Jixin Hamers, Robert J.},
    Number = {17},
    Pages = {6866-6876},
    Volume = {28},
    Abstract = {We demonstrate the formation of molecular monolayers of pi-conjugated organic molecules on nanocrystalline TiO2 surfaces through the thermal grafting of benzyl and aryl halides. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy were used to characterize the reactivity of aryl and benzyl chlorides, bromides, and iodides with TiO2 surfaces, along with controls consisting of nonhalogenated compounds. Our results show that benzyl and aryl halides follow a similar reactivity trend (I > Br > Cl >> H). While the ability to graft benzyl halides is consistent with the well-known Williamson ether synthesis, the grafting of aryl halides has no similar precedent. The unique reactivity of the TiO2 surface is demonstrated using nuclear magnetic resonance spectroscopy to compare the surface reactions with the liquid-phase interactions of benzyl and aryl iodides with tert-butanol and -butoidde anion. While the aryl iodides show no detectable reactivity with a tert-butanol/tert-butoxide mixture, they react with TiO2 within 2 h at 50 degrees C. Atomic force microscopy studies show that grafting of 4-iodo-1-(trifluoromethyl)benzene onto the rutile TiO2(110) surface leads to a very uniform, homogeneous molecular layer with a thickness of nm, demonstrating formation of a self-terminating molecular monolayer. Thermal grafting of aryl iodides provides a facile route to link pi-conjugated molecules to TiO2 surfaces with the shortest possible linkage between the conjugated electron system and the TiO2.},
    Doi = {10.1021/la300271h},
    ISSN = {0743-7463},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000303348900019
    http://pubs.acs.org/doi/abs/10.1021/la300271h}
    }
  • [DOI] Caban-Acevedo, M., M. S. Faber, Y. Z. Tan, R. J. Hamers, and S. Jin. Synthesis and Properties of Semiconducting Iron Pyrite (FeS2) Nanowires. Nano Letters 2012, 12, 1977-1982.
    [Bibtex]
    @Article{Hamers9,
    Title = {Synthesis and Properties of Semiconducting Iron Pyrite (FeS2) Nanowires},
    Author = {Caban-Acevedo, M. and Faber, M. S. and Tan, Y. Z. and Hamers, R. J. and Jin, S.},
    Journal = {Nano Letters},
    Year = {2012},
    Note = {Caban-Acevedo, Miguel Faber, Matthew S. Tan, Yizheng Hamers, Robert J. Jin, Song},
    Number = {4},
    Pages = {1977-1982},
    Volume = {12},
    Abstract = {We report the growth and structural, electrical, and optical characterization of vertically oriented single-crystalline iron pyrite (FeS2) nanowires synthesized via thermal sulfidation of steel foil for the first time. The pyrite nanowires have diameters of 4-10 nm and lengths greater than 2 mu m. Their crystal phase was identified as cubic iron pyrite using high-resolution transmission electron microscopy, Raman spectroscopy, and powder X-ray diffraction. Electrical transport measurements showed the pyrite nanowires to be highly p-doped, with an average resistivity of 0.18 +/- 0.09 Omega cm and carrier concentrations on the order of 10(21) cm(-3). These pyrite nanowires could provide a platform to further study and improve the physical properties of pyrite nanostructures toward solar energy conversion.},
    Doi = {10.1021/nl2045364},
    ISSN = {1530-6984},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000302524600040
    http://pubs.acs.org/doi/abs/10.1021/nl2045364}
    }

2011

  • [DOI] Ruther, R. E., R. Franking, A. M. Huhn, J. Gomez-Zayas, and R. J. Hamers. Formation of Smooth, Conformal Molecular Layers on ZnO Surfaces via Photochemical Grafting. Langmuir 2011, 27, 10604-10614.
    [Bibtex]
    @Article{Hamers16,
    Title = {Formation of Smooth, Conformal Molecular Layers on ZnO Surfaces via Photochemical Grafting},
    Author = {Ruther, R. E. and Franking, R. and Huhn, A. M. and Gomez-Zayas, J. and Hamers, R. J.},
    Journal = {Langmuir},
    Year = {2011},
    Note = {Ruther, Rose E. Franking, Ryan Huhn, Alex M. Gomez-Zayas, Jaritza Hamers, Robert J.},
    Number = {17},
    Pages = {10604-10614},
    Volume = {27},
    Abstract = {We have investigated the photochemical grafting of organic alkenes to atomically flat ZnO(10 (1) over bar0) single crystals and ZnO nanorods as a way to produce functional molecule-semiconductor interfaces. Atomic force microscopy shows that photochemical:grafting produces formal, smooth molecular layers With no detectable changes in the underlying structure of the ZnO terraces or steps. X-ray photoelectron spectroscopy measurements show that grafting of a methyl ester-terminated alkene-terminates near one monolayer, while alkenes bearing a trifluoroacetamide-protected amine form very smooth multilayers. Even with multilayers, it is possible to deprotect the amines and to link a second molecule to the surface with excellent efficiency and without significant loss of molecules from the surface. This demonstrates that the use of photochemical grafting, even in the case of multilayer formation, enables multistep chemical processes to be conducted on the ZnO surface. Photoresponse measurements demonstrate that functionalization of the surface does not affect the ability to induce. field effects in the underlying ZnO, thereby suggesting that this approach to functionalization may be useful for applications in sensing and in hybrid organic-inorganic transistors and related devices.},
    Doi = {10.1021/la2011265},
    ISSN = {0743-7463},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000294373300036
    http://pubs.acs.org/doi/abs/10.1021/la2011265}
    }
  • [DOI] Franking, R. and R. J. Hamers. Ultraviolet-Induced Grafting of Alkenes to TiO2 Surfaces: Controlling Multi layer Formation. Journal of Physical Chemistry C 2011, 115, 17102-17110.
    [Bibtex]
    @Article{Hamers17,
    Title = {Ultraviolet-Induced Grafting of Alkenes to TiO2 Surfaces: Controlling Multi layer Formation},
    Author = {Franking, R. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2011},
    Note = {Franking, Ryan Hamers, Robert J.},
    Number = {34},
    Pages = {17102-17110},
    Volume = {115},
    Abstract = {Photochemical grafting of alkenes has emerged as a versatile way to form functionalized surfaces and enables multistep surface chemistry on a range of substrates. However, the self-terminating nature of the reaction remains poorly understood. Here, we use X-ray photoelectron spectroscopy (XPS) to explore multilayer formation during photochemical grafting of functional alkenes on single-crystal rutile (110) TiO2 surfaces. We demonstrate that simple alkenes such as 1-hexene stop at 1 monolayer, but alkenes with an additional alcohol group easily form multilayers. Atomic force microscopy (AFM) and XPS studies show that the multilayers are highly conformal and that the alcohol groups remain chemically accessible even within rnultilayer films. Small amounts of water enhance multilayer formation by facilitating formation of center dot OH or other radical species that initiate oligomerization processes, while oxygen has little effect. We show that the multilayer formation can be reduced or eliminated by using small amounts of a radical scavenger or by modifying the molecular structure of the alkene. Overall these studies show that multilayer formation is controlled by the ability to form alkyl radicals under ultraviolet (UV) illumination.},
    Doi = {10.1021/jp205007z},
    ISSN = {1932-7447},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000294146700045
    http://pubs.acs.org/doi/abs/10.1021/jp205007z}
    }
  • [DOI] Benson, M. C., R. E. Ruther, J. B. Gerken, M. L. Rigsby, L. M. Bishop, Y. Z. Tan, S. S. Stahl, and R. J. Hamers. Modular "Click" Chemistry for Electrochemically and Photoelectrochemically Active Molecular Interfaces to Tin Oxide Surfaces. Acs Applied Materials & Interfaces 2011, 3, 3110-3119.
    [Bibtex]
    @Article{Hamers18,
    Title = {Modular "Click" Chemistry for Electrochemically and Photoelectrochemically Active Molecular Interfaces to Tin Oxide Surfaces},
    Author = {Benson, M. C. and Ruther, R. E. and Gerken, J. B. and Rigsby, M. L. and Bishop, L. M. and Tan, Y. Z. and Stahl, S. S. and Hamers, R. J.},
    Journal = {Acs Applied Materials \& Interfaces},
    Year = {2011},
    Note = {Benson, Michelle C. Ruther, Rose E. Gerken, James B. Rigsby, Matthew L. Bishop, Lee M. Tan, Yizheng Stahl, Shannon S. Hamers, Robert J.},
    Number = {8},
    Pages = {3110-3119},
    Volume = {3},
    Abstract = {We demonstrate the use of "click" chemistry to form electrochemically and photoelectrochemically active molecular interfaces to SnO(2) nanoparticle thin films. By using photochemical grafting to link a short-chain alcohol to the surface followed by conversion to a surface azide group, we enable use of the Cu(I)-catalyzed azide-alkyne [3 + 2] cycloaddition (CuAAC) reaction, a form of "click" chemistry, on metal oxide surfaces. Results are shown with three model compounds to test the surface chemistry and subsequent ability to achieve electrochemical and photoelectrochemical charge transfer. Surface-tethered ferrocene groups exhibit good electron-transfer characteristics with thermal rates estimated at >1000 s(-1). Time-resolved surface photovoltage measurements using a ruthenium terpyridyl coordination compound demonstrate photoelectron charge transfer on time scales of nanoseconds or less, limited by the laser pulse width. The results demonstrate that the CuAAC "click" reaction can be used to form electrochemically and photoelectrochemically active molecular interfaces to SnO(2) and other metal oxide semiconductors.},
    Doi = {10.1021/am200615r},
    ISSN = {1944-8244},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000294146900042
    http://pubs.acs.org/doi/abs/10.1021/am200615r}
    }
  • [DOI] Ruther, R. E., M. L. Rigsby, J. B. Gerken, S. R. Hogendoorn, E. C. Landis, S. S. Stahl, and R. J. Hamers. Highly Stable Redox-Active Molecular Layers by Covalent Grafting to Conductive Diamond. Journal of the American Chemical Society 2011, 133, 5692-5694.
    [Bibtex]
    @Article{Hamers21,
    Title = {Highly Stable Redox-Active Molecular Layers by Covalent Grafting to Conductive Diamond},
    Author = {Ruther, R. E. and Rigsby, M. L. and Gerken, J. B. and Hogendoorn, S. R. and Landis, E. C. and Stahl, S. S. and Hamers, R. J.},
    Journal = {Journal of the American Chemical Society},
    Year = {2011},
    Note = {Ruther, Rose E. Rigsby, Matthew L. Gerken, James B. Hogendoorn, Stephanie R. Landis, Elizabeth C. Stahl, Shannon S. Hamers, Robert J.},
    Number = {15},
    Pages = {5692-5694},
    Volume = {133},
    Abstract = {We demonstrate a modular "click"-based functionalization scheme that allows inexpensive conductive diamond samples to serve as an ultrastable platform for surface-tethered electrochemically active molecules stable out to similar to 1.3 V vs Ag/AgCl. We have cycled surface-tethered Ru(tpy)(2) to this potential more than 1 million times with little or no degradation in propylene carbonate and only slightly reduced stability in water and acetonitrile.},
    Doi = {10.1021/ja200210t},
    ISSN = {0002-7863},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000290358200020
    http://pubs.acs.org/doi/abs/10.1021/ja200210t}
    }
  • [DOI] Radadia, A. D., C. J. Stavis, R. Carr, H. J. Zeng, W. P. King, J. A. Carlisle, A. Aksimentiev, R. J. Hamers, and R. Bashir. Control of Nanoscale Environment to Improve Stability of Immobilized Proteins on Diamond Surfaces. Advanced Functional Materials 2011, 21, 1040-1050.
    [Bibtex]
    @Article{Hamers22,
    Title = {Control of Nanoscale Environment to Improve Stability of Immobilized Proteins on Diamond Surfaces},
    Author = {Radadia, A. D. and Stavis, C. J. and Carr, R. and Zeng, H. J. and King, W. P. and Carlisle, J. A. and Aksimentiev, A. and Hamers, R. J. and Bashir, R.},
    Journal = {Advanced Functional Materials},
    Year = {2011},
    Note = {Radadia, Adarsh D. Stavis, Courtney J. Carr, Rogan Zeng, Hongjun King, William P. Carlisle, John A. Aksimentiev, Aleksei Hamers, Robert J. Bashir, Rashid},
    Number = {6},
    Pages = {1040-1050},
    Volume = {21},
    Abstract = {Immunoassays for detection of bacterial pathogens rely on the selectivity and stability of bio-recognition elements such as antibodies tethered to sensor surfaces. The search for novel surfaces that improve the stability of biomolecules and assay performance has been pursued for a long time. However, the anticipated improvements in stability have not been realized in practice under physiological conditions because the surface functionalization layers on commonly used substrates, silica and gold, are themselves unstable on time scales of days. In this paper, we show that covalent linking of antibodies to diamond surfaces leads to substantial improvements in biological activity of proteins as measured by the ability to selectively capture cells of the pathogenic bacterium Escherichia coli O157:H7 even after exposure to buffer solutions at 37 degrees C for extended periods of time, approaching 2 weeks. Our results from ELISA, XPS, fluorescence microscopy, and MD simulations suggest that by using highly stable surface chemistry and controlling the nanoscale organization of the antibodies on the surface, it is possible to achieve significant improvements in biological activity and stability. Our findings can be easily extended to functionalization of micro and nanodimensional sensors and structures of biomedical diagnostic and therapeutic interest.},
    Doi = {10.1002/adfm.201002251},
    ISSN = {1616-301X},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000288559100004
    http://onlinelibrary.wiley.com/doi/10.1002/adfm.201002251/abstract?systemMessage=Wiley+Online+Library+will+be+disrupted+on+15+December+from+10%3A00-12%3A00+GMT+%2805%3A00-07%3A00+EST%29+for+essential+maintenance}
    }
  • [DOI] Spalenka, J. W., P. Paoprasert, R. Franking, R. J. Hamers, P. Gopalan, and P. G. Evans. Molecular control of pentacene/ZnO photoinduced charge transfer. Applied Physics Letters 2011, 98, .
    [Bibtex]
    @Article{Hamers23,
    Title = {Molecular control of pentacene/ZnO photoinduced charge transfer},
    Author = {Spalenka, J. W. and Paoprasert, P. and Franking, R. and Hamers, R. J. and Gopalan, P. and Evans, P. G.},
    Journal = {Applied Physics Letters},
    Year = {2011},
    Note = {Spalenka, Josef W. Paoprasert, Peerasak Franking, Ryan Hamers, Robert J. Gopalan, Padma Evans, Paul G.},
    Number = {10},
    Volume = {98},
    Abstract = {Photoinduced charge transfer modifies the device properties of illuminated pentacene field effect transistors (FETs) incorporating ZnO quantum dots at the gate insulator/pentacene interface. The transferred charge is trapped on electronic states associated with the ZnO quantum dots, with a steady state population approximately proportional to the rate of organic-inorganic charge transfer. Trapped charge shifts the threshold voltage of the FETs, providing the means to evaluate the rate of organic/inorganic charge transfer and the effects of interface modification. Monolayers of the wide-gap alkane stearic acid and the conjugated oligomer terthiophene attached to the ZnO suppress or permit charge transfer, respectively. (C) 2011 American Institute of Physics. [doi:10.1063/1.3560481]},
    Doi = {103303
    10.1063/1.3560481},
    ISSN = {0003-6951},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000288277200068
    http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=APPLAB000098000010103303000001&idtype=cvips&doi=10.1063/1.3560481&prog=normal&bypassSSO=1}
    }
  • [DOI] Peng, G. W., S. Seo, R. E. Ruther, R. J. Hamers, M. Mavrikakis, and P. G. Evans. Molecular-Scale Structure of a Nitrobenzene Monolayer on Si(001). Journal of Physical Chemistry C 2011, 115, 3011-3017.
    [Bibtex]
    @Article{Hamers24,
    Title = {Molecular-Scale Structure of a Nitrobenzene Monolayer on Si(001)},
    Author = {Peng, G. W. and Seo, S. and Ruther, R. E. and Hamers, R. J. and Mavrikakis, M. and Evans, P. G.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2011},
    Note = {Peng, Guowen Seo, Soonjoo Ruther, Rose E. Hamers, Robert J. Mavrikakis, Manos Evans, Paul G.},
    Number = {7},
    Pages = {3011-3017},
    Volume = {115},
    Abstract = {Nitrobenzene molecules can be attached to Si(001) by exposing the Si(001) (2 x 1) surface to nitrobenzene gas at room temperature. The resulting monolayer lacks long-range order in scanning tunneling microscopy images but shows signs of a local periodic arrangement of molecules. Self-consistent plane wave density functional theory calculations find that the energy gained per molecule in the adsorption of nitrobenzene is nearly constant as a function of nitrobenzene coverage and that it is energetically favorable to form coverages as high as one molecule per Si dimer. Ab initio molecular dynamics (AIMD) simulations show that the migration of oxygen transforms an initial configuration in which the nitrobenzene molecule bridges a Si dimer into lower energy configurations with oxygen separated from the nitrobenzene phenyl group. A previously unknown low-energy configuration, characteristic of SiO(2) bonding, is identified by the AIMD calculations. The energy barriers for O migration into Si backbonds are calculated by using the climbing-image nudged elastic band method. The calculated dipole moments of nitrobenzene on Si(001) varied from 0.11 to 0.45 D, depending on the molecular configuration. Nitrogen is observed using X-ray photoelectron spectroscopy in a concentration consistent with the attachment of one nitrobenzene molecule per Si dimer.},
    Doi = {10.1021/jp1069434},
    ISSN = {1932-7447},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000287338100015
    http://pubs.acs.org/doi/abs/10.1021/jp1069434}
    }
  • [DOI] Stavis, C., T. L. Clare, J. E. Butler, A. D. Radadia, R. Carr, H. J. Zeng, W. P. King, J. A. Carlisle, A. Aksimentiev, R. Bashir, and R. J. Hamers. Surface functionalization of thin-film diamond for highly stable and selective biological interfaces. Proceedings of the National Academy of Sciences of the United States of America 2011, 108, 983-988.
    [Bibtex]
    @Article{Hamers25,
    Title = {Surface functionalization of thin-film diamond for highly stable and selective biological interfaces},
    Author = {Stavis, C. and Clare, T. L. and Butler, J. E. and Radadia, A. D. and Carr, R. and Zeng, H. J. and King, W. P. and Carlisle, J. A. and Aksimentiev, A. and Bashir, R. and Hamers, R. J.},
    Journal = {Proceedings of the National Academy of Sciences of the United States of America},
    Year = {2011},
    Note = {Stavis, Courtney Clare, Tami Lasseter Butler, James E. Radadia, Adarsh D. Carr, Rogan Zeng, Hongjun King, William P. Carlisle, John A. Aksimentiev, Aleksei Bashir, Rashid Hamers, Robert J.},
    Number = {3},
    Pages = {983-988},
    Volume = {108},
    Abstract = {Carbon is an extremely versatile family of materials with a wide range of mechanical, optical, and mechanical properties, but many similarities in surface chemistry. As one of the most chemically stable materials known, carbon provides an outstanding platform for the development of highly tunable molecular and biomolecular interfaces. Photochemical grafting of alkenes has emerged as an attractive method for functionalizing surfaces of diamond, but many aspects of the surface chemistry and impact on biological recognition processes remain unexplored. Here we report investigations of the interaction of functionalized diamond surfaces with proteins and biological cells using X-ray photoelectron spectroscopy (XPS), atomic force microscopy, and fluorescence methods. XPS data show that functionalization of diamond with short ethylene glycol oligomers reduces the nonspecific binding of fibrinogen below the detection limit of XPS, estimated as >97% reduction over H-terminated diamond. Measurements of different forms of diamond with different roughness are used to explore the influence of roughness on nonspecific binding onto H-terminated and ethylene glycol (EG)-terminated surfaces. Finally, we use XPS to characterize the chemical stability of Escherichia coli K12 antibodies on the surfaces of diamond and amine-functionalized glass. Our results show that antibody-modified diamond surfaces exhibit increased stability in XPS and that this is accompanied by retention of biological activity in cell-capture measurements. Our results demonstrate that surface chemistry on diamond and other carbon-based materials provides an excellent platform for biomolecular interfaces with high stability and high selectivity.},
    Doi = {10.1073/pnas.1006660107},
    ISSN = {0027-8424},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000286310300021
    http://www.pnas.org/content/108/3/983.full.pdf}
    }
  • Chen, Jixin, Ryan Franking, Rose E. Ruther, Yizheng Tan, Xueying He, Stephanie R. Hogendoorn, and Robert J. Hamers. Formation of Molecular Monolayers on TiO2 Surfaces: A Surface Analogue of the Williamson Ether Synthesis. Langmuir 2011, 27, 6879-6889.
    [Bibtex]
    @Article{Hamers492,
    Title = {Formation of Molecular Monolayers on TiO2 Surfaces: A Surface Analogue of the Williamson Ether Synthesis},
    Author = {Chen, Jixin and Franking, Ryan and Ruther, Rose E. and Tan, Yizheng and He, Xueying and Hogendoorn, Stephanie R. and Hamers, Robert J.},
    Journal = {Langmuir},
    Year = {2011},
    Note = {English
    Article
    National Science Foundation [CHE0911543]; Dept. of Energy Office of Basic Energy Sciences [DE-SC0002160]},
    Number = {11},
    Pages = {6879-6889},
    Volume = {27},
    Abstract = {Strategies to modify metal oxide surfaces are important because of the increasing applications of metal oxides in catalysis, sensing, electronics, and renewable energy. Here, we report the formation of molecular monolayers on anatase nanocrystalline TiO2 surfaces at near-ambient temperatures by a simple one-step immersion. This is achieved by an analogue of the Williamson ether synthesis, in which the hydroxyl groups of the TiO2 surface react with iodo-alkane molecules to release HI and form a Ti-O-C surface linkage. The grafted molecules were characterized by Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) to confirm the formation of covalently bonded monolayers. Kinetic studies yielded an activation barrier of similar to 59 kJ/mol for the grafting reaction. Measurements of hydrolytic stability of the grafted molecules in water show that approximately half the molecules are removed within minutes to hours at temperatures of 25-100 degrees C with an activation energy of similar to 82 kJ/mol, while the remaining molecules are stable for much longer periods of time. These different stabilities are discussed in terms of the different types of Ti-O-C bonds that can form on TiO2 surfaces.},
    Keywords = {Self-assembled monolayers
    metal-oxide catalysts
    field-effect
    transistors
    aliphatic-alcohols
    cycloaddition chemistry
    semiconductor
    surfaces
    vibrational-spectra
    tio2(110) surface
    hydroxyl-groups
    porous silicon
    Chemistry, Multidisciplinary
    Chemistry, Physical
    Materials Science,
    Multidisciplinary},
    Type = {Journal Article}
    }
  • Gonzalez-Moreno, Ruben, Peter L. Cook, Ioannis Zegkinoglou, Xiaosong Liu, Phillip S. Johnson, Wanli Yang, Rose E. Ruther, Robert J. Hamers, Ramon Tena-Zaera, F. J. Himpsel, J. Enrique Ortega, and Celia Rogero. Attachment of Protoporphyrin Dyes to Nanostructured ZnO Surfaces: Characterization by Near Edge X-ray Absorption Fine Structure Spectroscopy. Journal of Physical Chemistry C 2011, 115, 18195-18201.
    [Bibtex]
    @Article{Hamers494,
    Title = {Attachment of Protoporphyrin Dyes to Nanostructured ZnO Surfaces: Characterization by Near Edge X-ray Absorption Fine Structure Spectroscopy},
    Author = {Gonzalez-Moreno, Ruben and Cook, Peter L. and Zegkinoglou, Ioannis and Liu, Xiaosong and Johnson, Phillip S. and Yang, Wanli and Ruther, Rose E. and Hamers, Robert J. and Tena-Zaera, Ramon and Himpsel, F. J. and Enrique Ortega, J. and Rogero, Celia},
    Journal = {Journal of Physical Chemistry C},
    Year = {2011},
    Note = {English
    Article
    Spanish research projects[PET2008-109, BIO 2007-67523]; intramural project[2009601159]; HOPE CSD; Spanish MICINN[PIB2010US 00652, MAT2010-21156-CO3-01, MAT2010-21156-CO3-03]; Basque Government[IT-257-07]; NSF[CHE-1026245, DMR-0537588]; DOE[DE-FG02-01ER45917, DEACO3-76SF00098]; DOE Basic Energy Sciences[DE-FG02-09ER16122]; MICINN
    819ZM},
    Number = {37},
    Pages = {18195-18201},
    Volume = {115},
    Abstract = {The attachment of Hr and metal (Co- and Zn-) protoporphyrin IX molecules to ZnO nanorods and single-crystal surfaces is investigated by Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. The carboxyl groups of the protoporphyrin are found to be essential for anchoring the molecules to ZnO surfaces. The crystallographic orientation of the exposed ZnO face has an influence on the dye immobilization, with the highest uptake observed for the oxygen-terminated ZnO (000-1) surface. The preparation conditions are crucial for the dye immobilization. Under certain preparation conditions, there is a Zn atom exchange between the H(2)-protoporphyrin and the ZnO surface, i.e., a metalation of H(2) protoporphyrin IX to form Zn-protoporphyrin. Moreover, in the presence of chenodeoxycholic acid as coabsorber, the ZnO single-crystal surfaces are etched, as indicated by the loss of the orientation-dependent spectral features. These results help to pinpoint the chemical reactions that are responsible sensitized solar cells, especially those built from ZnO nanorod arrays. for the poor efficiency of ZnO-based dyesensitized solar cells, especially those built from ZnO nanorod arrays.},
    Keywords = {Sensitized solar-cells
    conjugated organic-dyes
    conversion efficiency
    photovoltaic performance
    electron injection
    adsorbing groups
    tio2
    films
    adsorption
    nanowires
    oxide
    Chemistry
    Science & Technology - Other Topics
    Materials Science},
    Type = {Journal Article}
    }
  • Hamers, Robert J., Courtney Stavis, Ankit Pokhrel, Ryan Franking, Rose E. Ruther, Xiaoyu Wang, Michelle C. Cooperrider, Hongjun Zheng, John A. Carlisle, and James E. Butler. Characterization of molecular and biomolecular layers on diamond thin films by infrared reflection-absorption spectroscopy. Diamond and Related Materials 2011, 20, 733-742.
    [Bibtex]
    @Article{Hamers495,
    Title = {Characterization of molecular and biomolecular layers on diamond thin films by infrared reflection-absorption spectroscopy},
    Author = {Hamers, Robert J. and Stavis, Courtney and Pokhrel, Ankit and Franking, Ryan and Ruther, Rose E. and Wang, Xiaoyu and Cooperrider, Michelle C. and Zheng, Hongjun and Carlisle, John A. and Butler, James E.},
    Journal = {Diamond and Related Materials},
    Year = {2011},
    Note = {English
    Proceedings Paper},
    Number = {5-6},
    Pages = {733-742},
    Volume = {20},
    Abstract = {We explore the use of single-bounce infrared reflection-absorption spectroscopy (IRRAS) to characterize molecular and biomolecular layers on doped and undoped diamond thin films on silicon substrates. Experimental measurements of thin layers of poly(methyl methacrylate) (PMMA) as a function of polarization and angle of incidence were used to characterize the intensity, frequency, and symmetry of the vibrational features. Fresnel multilayer reflectivity calculations were used to identify optimized conditions and to understand the observed trends. The measurements were then extended to characterize the nonspecific binding of fibrinogen as a model system. Finally, we present data demonstrating the ability to characterize Escherichia coli antibodies covalently linked to diamond surfaces, including changes in Amide I band due to conformational changes associated with protein denaturation. Our results show that dispersion and reflection effects under different experimental conditions lead to changes in the frequency of the PMMA C=O mode and the fibrinogen Amide I band that are comparable to the changes due to different protein conformations. This has significant implications for the use of the Amide I feature to analyze the conformation of proteins on diamond thin film and highlights the utility of Fresnel modeling in the interpretation of FTIR spectra at surfaces. (C) 2011 Elsevier B.V. All rights reserved.},
    Keywords = {Diamond
    Fibrinogen
    Proteins
    E. coli
    Biomolecular layers
    Infrared
    spectroscopy
    Conformational-changes
    adsorbed fibrinogen
    protein adsorption
    surfaces
    spectra
    interface
    water
    Materials Science, Multidisciplinary},
    Type = {Journal Article}
    }
  • Hamers, R. J.. 2011. Immobilization of biomolecules at semiconductor surfaces. Edited by Tao, F. and S. Bernasek. In Functionalization of semiconductor surfaces, J. Wiley and Sons. .
    [Bibtex]
    @InBook{Hamers522,
    Title = {Immobilization of biomolecules at semiconductor surfaces},
    Author = {Hamers, R. J.},
    Editor = {Tao, F. and Bernasek, S.},
    Publisher = {J. Wiley and Sons},
    Year = {2011},
    Type = {Book Section},
    Booktitle = {Functionalization of semiconductor surfaces}
    }
  • Hamers, R. J., Xiaoyu Wang, R. Franking, R. Ruther, and CS. Stavis. 2011. Infrared spectroscopy for characterization of biomolecular interfaces. Edited by Pradier, C. M. and Y. Chabal. In Biointerface characterization by advanced IR spectroscopy, Elsevier Press. .
    [Bibtex]
    @InBook{Hamers523,
    Title = {Infrared spectroscopy for characterization of biomolecular interfaces},
    Author = {Hamers, R. J. and Wang, Xiaoyu and Franking, R. and Ruther, R. and Stavis, CS.},
    Editor = {Pradier, C. M. and Chabal, Y.},
    Publisher = {Elsevier Press},
    Year = {2011},
    Type = {Book Section},
    Booktitle = {Biointerface characterization by advanced IR spectroscopy}
    }

2010

  • [DOI] Paoprasert, P., J. E. Laaser, W. Xiong, R. A. Franking, R. J. Hamers, M. T. Zanni, J. R. Schmidt, and P. Gopalan. Bridge-Dependent Interfacial Electron Transfer from Rhenium-Bipyridine Complexes to TiO2 Nanocrystalline Thin Films. Journal of Physical Chemistry C 2010, 114, 9898-9907.
    [Bibtex]
    @Article{Hamers28,
    Title = {Bridge-Dependent Interfacial Electron Transfer from Rhenium-Bipyridine Complexes to TiO2 Nanocrystalline Thin Films},
    Author = {Paoprasert, P. and Laaser, J. E. and Xiong, W. and Franking, R. A. and Hamers, R. J. and Zanni, M. T. and Schmidt, J. R. and Gopalan, P.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2010},
    Note = {Paoprasert, Peerasak Laaser, Jennifer E. Xiong, Wei Franking, Ryan A. Hamers, Robert J. Zanni, Martin T. Schmidt, J. R. Gopalan, Padma},
    Number = {21},
    Pages = {9898-9907},
    Volume = {114},
    Abstract = {We have measured the electron injection kinetics of four rhenium bipyridine complexes (Re1C, ReEC, Re1TC, and Re2TC) on TiO2 nanocrystalline films using transient infrared spectroscopy. The self-assembled monolayer formation of these complexes was characterized by UV-visible spectroscopy, infrared reflection absorption spectroscopy, and X-ray photoelectron spectroscopy. These complexes bind to the TiO2 surface through the formation of carboxylate groups, and these self-assembled layers are approximately a monolayer. The kinetics studies address the effect of insulating and conjugated spacers and the length of conjugation on the electron-transfer process. The insulating bridge leads to a slower injection rate and poorer injection yield compared with the conjugated spacers. The electron injection of Re2TC was found to be a fast, high-yielding, and multiple electron injector process. The ground and electronically excited states of the dye complexes were characterized using ground-state and time-dependent density functional theory. We present the role of electronic conjugation in modulating electron injection using a combination of computational and experimental work and find that these metal-based complexes adsorbed on a semiconductor surface can be used to read out the electron injection kinetics through tailored molecular bridges.},
    Doi = {10.1021/jp102022d},
    ISSN = {1932-7447},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000278003700047
    http://pubs.acs.org/doi/abs/10.1021/jp102022d}
    }
  • [DOI] Landis, E. C., K. L. Klein, A. Liao, E. Pop, D. K. Hensley, A. V. Melechko, and R. J. Hamers. Covalent Functionalization and Electron-Transfer Properties of Vertically Aligned Carbon Nanofibers: The Importance of Edge-Plane Sites. Chemistry of Materials 2010, 22, 2357-2366.
    [Bibtex]
    @Article{Hamers29,
    Title = {Covalent Functionalization and Electron-Transfer Properties of Vertically Aligned Carbon Nanofibers: The Importance of Edge-Plane Sites},
    Author = {Landis, E. C. and Klein, K. L. and Liao, A. and Pop, E. and Hensley, D. K. and Melechko, A. V. and Hamers, R. J.},
    Journal = {Chemistry of Materials},
    Year = {2010},
    Note = {Landis, Elizabeth C. Klein, Kate L. Liao, Albert Pop, Eric Hensley, Dale K. Melechko, Anatoli V. Hamers, Robert J.},
    Number = {7},
    Pages = {2357-2366},
    Volume = {22},
    Abstract = {The use of covalently bonded molecular layers provides a way to combine the outstanding stability and electrochemical properties of carbon-based structures with the unique properties of molecular structures for applications such as electrocatalysis and solar conversion. The functionalization of vertically aligned carbon nanofibers (VACNFs) with 1-alkenes, using ultraviolet light, was investigated as a potential way to impart a variety of different functional groups onto the nanofiber sidewalls. We report how variations in the nanofiber growth rate impact both the amount of exposed edge-plane sites and the resulting electrochemical activity toward Ru(NH(3))(6)(3+/2+) and Fe(CN)(6)(3-/4-) redox couples. Measurements of the distribution of surface oxides show that surface oxides are unaffected by the grafting of alkenes to the nanofibers. Carbon nanofiber reactivity was also compared to multiwalled and single-walled carbon nanotubes. Our results demonstrate that edge-plane sites are preferred sites for photochemical grafting, but that the grafting of molecular layers only slightly reduces the overall electrochemical activity of the nanofibers toward the Ru(NH(3))(6)(3+/2+) couple. These results provide new insights into the relationships between the chemical reactivity and electrochemical properties of nanostructured carbon materials and highlight the crucial role that exposed edge-plane sites play in the electrochemical properties of carbon nanotubes and nanofibers.},
    Doi = {10.1021/cm9036132},
    ISSN = {0897-4756},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000276394800025
    http://pubs.acs.org/doi/abs/10.1021/cm9036132}
    }
  • [DOI] Gerken, J. B., E. C. Landis, R. J. Hamers, and S. S. Stahl. Fluoride-Modulated Cobalt Catalysts for Electrochemical Oxidation of Water under Non-Alkaline Conditions. Chemsuschem 2010, 3, 1176-1179.
    [Bibtex]
    @Article{Hamers35,
    Title = {Fluoride-Modulated Cobalt Catalysts for Electrochemical Oxidation of Water under Non-Alkaline Conditions},
    Author = {Gerken, J. B. and Landis, E. C. and Hamers, R. J. and Stahl, S. S.},
    Journal = {Chemsuschem},
    Year = {2010},
    Note = {Gerken, James B. Landis, Elizabeth C. Hamers, Robert J. Stahl, Shannon S.},
    Number = {10},
    Pages = {1176-1179},
    Volume = {3},
    Doi = {10.1002/cssc.201000161},
    ISSN = {1864-5631},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000284134500022
    http://onlinelibrary.wiley.com/doi/10.1002/cssc.201000161/abstract?systemMessage=Wiley+Online+Library+will+be+disrupted+on+15+December+from+10%3A00-12%3A00+GMT+%2805%3A00-07%3A00+EST%29+for+essential+maintenance}
    }
  • [DOI] Paoprasert, P., J. W. Spalenka, D. L. Peterson, R. E. Ruther, R. J. Hamers, P. G. Evans, and P. Gopalan. Grafting of poly(3-hexylthiophene) brushes on oxides using click chemistry. Journal of Materials Chemistry 2010, 20, 2651-2658.
    [Bibtex]
    @Article{Hamers36,
    Title = {Grafting of poly(3-hexylthiophene) brushes on oxides using click chemistry},
    Author = {Paoprasert, P. and Spalenka, J. W. and Peterson, D. L. and Ruther, R. E. and Hamers, R. J. and Evans, P. G. and Gopalan, P.},
    Journal = {Journal of Materials Chemistry},
    Year = {2010},
    Note = {Paoprasert, Peerasak Spalenka, Josef W. Peterson, Dane L. Ruther, Rose E. Hamers, Robert J. Evans, Paul G. Gopalan, Padma},
    Number = {13},
    Pages = {2651-2658},
    Volume = {20},
    Abstract = {Poly(3-hexylthiophene) (P3HT) brushes on silicon dioxide (SiO(2)) were prepared using a click reaction between ethynyl-terminated P3HT and an azide self-assembled monolayer (SAM). Regioregular ethynyl-terminated P3HT with molecular weight of 5900 g mol(-1) and polydispersity of 1.2 was synthesized by catalyst-transfer polycondensation using Grignard metathesis mediated by a nickel-based catalyst. The azide SAM was prepared from bifunctional molecules containing azide and siloxane as click reaction precursor and surface linker, respectively. The P3HT brushes were characterized by atomic force microscopy, ellipsometry, X-ray photoelectron spectroscopy, infrared reflection absorption spectroscopy, and UV-visible spectroscopy. The grafting of P3HT brushes was studied as a function of click reaction time and the growth of the brushes is governed by a diffusion-controlled process. P3HT brushes were prepared on pre-fabricated field-effect transistor structures in order to probe the electrical properties of the brushes. The versatile synthetic methodology developed in this work can be generalized to prepare a wide variety of semiconducting conjugated polymer brushes on oxide surfaces relevant to organic electronic devices.},
    Doi = {10.1039/b920233a},
    ISSN = {0959-9428},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000275662400016
    http://pubs.rsc.org/en/Content/ArticleLanding/2010/JM/b920233a}
    }
  • Wang, Xiaoyu, Paula E. Colavita, Jeremy A. Streifer, James E. Butler, and Robert J. Hamers. Photochemical Grafting of Alkenes onto Carbon Surfaces: Identifying the Roles of Electrons and Holes. Journal of Physical Chemistry C 2010, 114, 4067-4074.
    [Bibtex]
    @Article{Hamers487,
    Title = {Photochemical Grafting of Alkenes onto Carbon Surfaces: Identifying the Roles of Electrons and Holes},
    Author = {Wang, Xiaoyu and Colavita, Paula E. and Streifer, Jeremy A. and Butler, James E. and Hamers, Robert J.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2010},
    Note = {English
    Article
    National Science Foundation [CHE-0613010, CHE-0911543]; Office of Naval Rescarch/Naval Research Laboratory},
    Number = {9},
    Pages = {4067-4074},
    Volume = {114},
    Abstract = {We report a mechanistic investigation of the charge transfer processes that Occur during photochemical grafting of liquid alkenes to H-terminated surfaces of diamond and amorphous carbon. Spectrally resolved photoelectron yield experiments were performed to directly characterize the photoemission of electrons from the hydrogen-terminated Surfaces into liquid alkenes, using trifluoroacetamide-protected 1-aminodec-l-ene (TFAAD) and 10-N-Boc-aminodec-l-ene (tBoc) as model alkenes having different terminal acceptor groups; 1-dodecene Was also used as a control. Corresponding X-ray and ultraviolet photoelectron spectroscopy measurements (XPS, UPS) establish a clear correlation between the photoelectron yield, the grafting efficiency at different wavelengths, and the valence electronic structure Of the Substrate and of the reactant molecule. Direct imaging of the Molecular layers via scanning electron microscopy shows that there are substantial differences ill the sharpness of molecular patterns that can be produced on single-crystal type Ib (low-mobility) and type IIb (high-mobility) diamond samples. Our results demonstrate that electrons and holes both play important and distinct roles in the photochemical grafting of alkenes to diamond and amorphous carbon surfaces.},
    Keywords = {Covalently attached monolayers
    hydrogen-terminated diamond
    extremely
    mild attachment
    thin-films
    doped diamond
    photoelectron-spectroscopy
    biomolecular recognition
    absorption-spectra
    visible-light
    cvd diamond
    Chemistry, Physical
    Nanoscience & Nanotechnology
    Materials Science,
    Multidisciplinary},
    Type = {Journal Article}
    }
  • Wang, Xiaoyu, Elizabeth C. Landis, Ryan Franking, and Robert J. Hamers. Surface Chemistry for Stable and Smart Molecular and Biomolecular Interfaces via Photochemical Grafting of Alkenes. Accounts of Chemical Research 2010, 43, 1205-1215.
    [Bibtex]
    @Article{Hamers488,
    Title = {Surface Chemistry for Stable and Smart Molecular and Biomolecular Interfaces via Photochemical Grafting of Alkenes},
    Author = {Wang, Xiaoyu and Landis, Elizabeth C. and Franking, Ryan and Hamers, Robert J.},
    Journal = {Accounts of Chemical Research},
    Year = {2010},
    Note = {English
    Review
    National Science Foundation [CHE0314618, CHE0613010, CHE0911543, DMR-0210806, DMR-0706559]},
    Number = {9},
    Pages = {1205-1215},
    Volume = {43},
    Abstract = {Many emerging fields such as biotechnology and renewable energy require functionalized surfaces that are "smart" and highly stable. Surface modification schemes developed previously have often been limited to simple molecules or have been based on weakly bound layers that have limited stability. In this Account, we report on recent developments enabling the preparation of molecular and biomolecular interfaces that exhibit high selectivity and unprecedented stability on a range of covalent materials including diamond, vertically aligned carbon nanofibers, silicon, and metal oxides. One particularly successful pathway to ultrastable interfaces involves the photochemical grafting of organic alkenes to the surfaces. Bifunctional alkenes with a suitable functional group at the distal end can directly impart functionality and can serve as attachment points for linking complex structures such as DNA and proteins. The successful application of photochemical grafting to a surprisingly wide range of materials has motivated researchers to better understand the underlying photochemical reaction mechanisms. The resulting studies using experimental and computational methods have provided fundamental insights into the electronic structure of the molecules and the surface control photochemical reactivity. Such investigations have revealed the important role of a previously unrecognized process, photoelectron emission, in initiating photochemical grafting of alkenes to surfaces. Molecular and biomolecular interfaces formed on diamond and other covalent materials are leading to novel types of molecular electronic interfaces. For example, electrical, optical, or electromechanical structures that convert biological information directly into analytical signals allow for direct label-free detection of DNA and proteins. Because of the preferential adherence of molecules to graphitic edge-plane sites, the grafting of redox-active species to vertically aligned carbon nanofibers leads to good electrochemical activity. Therefore researchers could graft electrocatalytic materials to carbon nanofibers to develop new types of selective electrocatalytic interfaces. Extending this chemistry to include metal oxides such as TiO2 may lead to highly specific and efficient chemical reactions and new materials with useful applications in photovoltaic and photocatalytic energy conversion.},
    Keywords = {Aligned carbon nanofibers
    direct electrical detection
    diamond
    thin-films
    silicon surfaces
    covalent functionalization
    photoelectron
    ejection
    protein adsorption
    amorphous-carbon
    dna
    monolayers
    Chemistry, Multidisciplinary},
    Type = {Journal Article}
    }
  • Wang, Xiaoyu, Rose E. Ruther, Jeremy A. Streifer, and Robert J. Hamers. UV-Induced Grafting of Alkenes to Silicon Surfaces: Photoemission versus Excitons. Journal of the American Chemical Society 2010, 132, 4048-+.
    [Bibtex]
    @Article{Hamers489,
    Title = {UV-Induced Grafting of Alkenes to Silicon Surfaces: Photoemission versus Excitons},
    Author = {Wang, Xiaoyu and Ruther, Rose E. and Streifer, Jeremy A. and Hamers, Robert J.},
    Journal = {Journal of the American Chemical Society},
    Year = {2010},
    Note = {English
    Article
    National Science Foundation [CHE-0613010, CHE-0911543]},
    Number = {12},
    Pages = {4048-+},
    Volume = {132},
    Abstract = {The mechanism of photochemical grafting of alkenes to H-terminated silicon has remained poorly understood. Here we demonstrate the importance of a previously unrecognized initiation process, photoelectron ejection (photoemission), as a facile way of initiating photochemical grafting of liquid alkenes to silicon surfaces when using ultraviolet light. A comparison of Si samples with vastly different photocarrier lifetimes showed no difference in the efficiency of alkene grafting. However, differences in the reactivities of different alkenes with different terminal groups that correlate with the electron affinities of these groups were observed. Our results indicate that photoemission is an effective way of initiating grafting because the irreversible nature of photoemission leaves the sample with a net excess of holes that have no corresponding electrons with which to recombine, while in a competing exciton mechanism, the net concentration of holes is limited by recombination processes.},
    Keywords = {Hydrogen-terminated silicon
    covalently attached monolayers
    extremely
    mild attachment
    visible-light
    organic monolayers
    alkyl monolayers
    porous silicon
    functionalization
    hydrosilylation
    chain
    Chemistry, Multidisciplinary},
    Type = {Journal Article}
    }
  • Zhang, Lingzhi, Leslie Lyons, Jocelyn Newhouse, Zhengcheng Zhang, Megan Straughan, Zonghai Chen, Khalil Amine, Robert J. Hamers, and Robert West. Synthesis and characterization of alkylsilane ethers with oligo(ethylene oxide) substituents for safe electrolytes in lithium-ion batteries. Journal of Materials Chemistry 2010, 20, 8224-8226.
    [Bibtex]
    @Article{Hamers490,
    Title = {Synthesis and characterization of alkylsilane ethers with oligo(ethylene oxide) substituents for safe electrolytes in lithium-ion batteries},
    Author = {Zhang, Lingzhi and Lyons, Leslie and Newhouse, Jocelyn and Zhang, Zhengcheng and Straughan, Megan and Chen, Zonghai and Amine, Khalil and Hamers, Robert J. and West, Robert},
    Journal = {Journal of Materials Chemistry},
    Year = {2010},
    Note = {English
    Article
    National Science Foundation [0724469]; Ministry of Education, Science and Technology [R33-10082]; Chinese Academy of Sciences ; NSFC [0901021001]; NIH [NIH 1 S10 RRO 8389-01, CHE-96296887]; NSF-MRI [0116159]},
    Number = {38},
    Pages = {8224-8226},
    Volume = {20},
    Abstract = {Alkylsilane ethers, containing one or three carbon spacer groups between the silicon atom and oligo(ethylene oxide) moiety, were designed and synthesized. These compounds are non-hydrolyzable and less flammable than their alkoxysilane counterparts. A full cell test using them as electrolyte solvents showed good cycling performance in lithium-ion batteries.},
    Keywords = {Polymers
    liquids
    Chemistry, Physical
    Materials Science, Multidisciplinary},
    Type = {Journal Article}
    }
  • Hamers, R. J., S. A. Chambers, P. G. Evans, R. Franking, Z. Gerbec, P. Gopalan, H. Kim, E. C. Landis, B. Li, M. W. McCoy, T. Ohsawa, and R. Ruther. Molecular and Biomolecular Interfaces to Metal Oxide Semiconductors. Physical Status Solidi 2010, 7, 200-205.
    [Bibtex]
    @Article{Hamers538,
    Title = {Molecular and Biomolecular Interfaces to Metal Oxide Semiconductors},
    Author = {Hamers, R. J. and Chambers, S. A. and Evans, P. G. and Franking, R. and Gerbec, Z. and Gopalan, P. and Kim, H. and Landis, E. C. and Li, B. and McCoy, M.W. and Ohsawa, T. and Ruther, R.},
    Journal = {Physical Status Solidi},
    Year = {2010},
    Pages = {200-205},
    Volume = {7},
    Type = {Journal Article}
    }

2009

  • [DOI] Xiong, W., J. E. Laaser, P. Paoprasert, R. A. Franking, R. J. Hamers, P. Gopalan, and M. T. Zanni. Transient 2D IR Spectroscopy of Charge Injection in Dye-Sensitized Nanocrystalline Thin Films. Journal of the American Chemical Society 2009, 131, 18040-+.
    [Bibtex]
    @Article{Hamers38,
    Title = {Transient 2D IR Spectroscopy of Charge Injection in Dye-Sensitized Nanocrystalline Thin Films},
    Author = {Xiong, W. and Laaser, J. E. and Paoprasert, P. and Franking, R. A. and Hamers, R. J. and Gopalan, P. and Zanni, M. T.},
    Journal = {Journal of the American Chemical Society},
    Year = {2009},
    Note = {Xiong, Wei Laaser, Jennifer E. Paoprasert, Peerasak Franking, Ryan A. Hamers, Robert J. Gopalan, Padma Zanni, Martin T.},
    Number = {50},
    Pages = {18040-+},
    Volume = {131},
    Abstract = {We use nonlinear 2D IR spectroscopy to study TiO(2) nanocrystalline thin films sensitized with a Re dye. We find that the free electron signal, which often obscures the vibrational features in the transient absorption spectrum, is not observed in the 2D IR spectra. Its absence allows the vibrational features of the dye to be much better resolved than with the typical IR absorption probe, We observe multiple absorption bands but no cross peaks in the 2D IR spectra, which indicates that the dyes have at least three conformations. Furthermore, by using a pulse sequence in which we initiate electron transfer in the middle of the infrared pulse train, we are able to assign the excited state features by correlating them to the ground state vibrational modes and determine that the three conformations have different time scales and cross sections for electron injection. 2D IR spectroscopy is proving to be very useful in disentangling overlapping structural distributions in biological and chemical physics processes. These experiments demonstrate that nonlinear infrared probes are also a powerful new tool. for studying charge transfer at interfaces.},
    Doi = {10.1021/ja908479r},
    ISSN = {0002-7863},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000273615400015
    http://pubs.acs.org/doi/abs/10.1021/ja908479r}
    }
  • [DOI] Uhlrich, J. J., R. Franking, R. J. Hamers, and T. F. Kuech. Sulfide Treatment of ZnO Single Crystals and Nanorods and the Effect on P3HT-ZnO Photovoltaic Device Properties. Journal of Physical Chemistry C 2009, 113, 21147-21154.
    [Bibtex]
    @Article{Hamers39,
    Title = {Sulfide Treatment of ZnO Single Crystals and Nanorods and the Effect on P3HT-ZnO Photovoltaic Device Properties},
    Author = {Uhlrich, J. J. and Franking, R. and Hamers, R. J. and Kuech, T. F.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2009},
    Note = {Uhlrich, John J. Franking, Ryan Hamers, Robert J. Kuech, Thomas F.},
    Number = {50},
    Pages = {21147-21154},
    Volume = {113},
    Abstract = {Surface chemical changes or passivation can be used to enhance the electrical performance of device Structures. The solution-based (Nh(4))(2)S(t), treatment of ZnO single crystals of (0001), (10 (1) over bar0), and (000 (1) over bar) orientations as well as ZnO nanorods was studies by using X-ray and Ultraviolet photoelectron spectroscopies (XPS and ups). The (10 (1) over bar0) and (000 (1) over bar)-onented single crystals and ZnO nanorods each showed evidence that the ZnO was consumed, forming a ZnS layer at the surface In contrast, the ZnO (0001) crystal (lid not substantially react with the sulfide Solution. However, the surface hydroxyl species were displaced by a Sulfide passivation layer of 0.21 ML. This process resulted in all apparent increase in upward band bending by similar to 0.1 -0.3 eV. P3HT-ZnO photovoltaic devices fabricated oil O-polar single crystals showed electrical properties which can be correlated with ZnS formation due to the Sulfide treatment.},
    Doi = {10.1021/jp906566v},
    ISSN = {1932-7447},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000272560400019
    http://pubs.acs.org/doi/abs/10.1021/jp906566v}
    }
  • [DOI] Franking, R. A., E. C. Landis, and R. J. Hamers. Highly Stable Molecular Layers on Nanocrystalline Anatase TiO2 through Photochemical Grafting. Langmuir 2009, 25, 10676-10684.
    [Bibtex]
    @Article{Hamers40,
    Title = {Highly Stable Molecular Layers on Nanocrystalline Anatase TiO2 through Photochemical Grafting},
    Author = {Franking, R. A. and Landis, E. C. and Hamers, R. J.},
    Journal = {Langmuir},
    Year = {2009},
    Note = {Franking, Ryan A. Landis, Elizabeth C. Hamers, Robert J.},
    Number = {18},
    Pages = {10676-10684},
    Volume = {25},
    Abstract = {Well-defined molecular layers can be formed on the surface of nanocrystalline anatase TiO2 by photochemically grafting organic molecules bearing a terminal vinyl group. The molecular layers produced are shown to have minimal oxidation and are able to be patterned and uniformly grafted through optically thick nanocrystalline films. Stability tests show that the layers have excellent stability in deionized water at 80 degrees C, aqueous solutions at pH = 1.0 and pH = 10.3 at 65 degrees C, and acetonitrile for time scales approaching 1200 h. Degradation of the films in deionized water occurs using a AM1.5 full-spectrum solar simulator as an illumination Source but is partially suppressed by filtering with a 400 nm UV blocking filter which blocks the above-bandgap light. A mechanism is proposed for the grafting reaction in which the Surface hydroxyl groups trap photoexcited holes, facilitating reaction with the vinyl group.},
    Doi = {10.1021/la901116c},
    ISSN = {0743-7463},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000269655000038
    http://pubs.acs.org/doi/abs/10.1021/la901116c}
    }
  • Mangham, A. N., K. M. Louis, A. M. Bramson, K. M. Metz, J. A. Pedersen, and R. J. Hamers. Ligand effects on the oxidative stability of CdSe nanoparticles. Geochimica Et Cosmochimica Acta 2009, 73, A827-A827.
    [Bibtex]
    @Article{Hamers41,
    Title = {Ligand effects on the oxidative stability of CdSe nanoparticles},
    Author = {Mangham, A. N. and Louis, K. M. and Bramson, A. M. and Metz, K. M. and Pedersen, J. A. and Hamers, R. J.},
    Journal = {Geochimica Et Cosmochimica Acta},
    Year = {2009},
    Note = {Mangham, A. N. Louis, K. M. Bramson, A. M. Metz, K. M. Pedersen, J. A. Hamers, R. J.
    19th Annual VM Goldschmidt Conference
    Jun 21, 2009
    Davos, SWITZERLAND
    S},
    Number = {13},
    Pages = {A827-A827},
    Volume = {73},
    ISSN = {0016-7037},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000267229902113}
    }
  • Wiecinski, P. N., T. C. K. Heiden, K. M. Metz, A. N. Mangham, R. J. Hamers, W. Heideman, R. E. Peterson, and J. A. Pedersen. Developmental toxicity of oxidatively degraded quantum dots. Geochimica Et Cosmochimica Acta 2009, 73, A1437-A1437.
    [Bibtex]
    @Article{Hamers42,
    Title = {Developmental toxicity of oxidatively degraded quantum dots},
    Author = {Wiecinski, P. N. and Heiden, T. C. K. and Metz, K. M. and Mangham, A. N. and Hamers, R. J. and Heideman, W. and Peterson, R. E. and Pedersen, J. A.},
    Journal = {Geochimica Et Cosmochimica Acta},
    Year = {2009},
    Note = {Wiecinski, Paige N. Heiden, Tisha C. King Metz, Kevin M. Mangham, Andrew N. Hamers, Robert J. Heideman, Warren Peterson, Richard E. Pedersen, Joel A.
    19th Annual VM Goldschmidt Conference
    Jun 21, 2009
    Davos, SWITZERLAND},
    Number = {13},
    Pages = {A1437-A1437},
    Volume = {73},
    ISSN = {0016-7037},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000267229903562}
    }
  • [DOI] Li, B., R. Franking, E. C. Landis, H. Kim, and R. J. Hamers. Photochemical Grafting and Patterning of Biomolecular Layers onto TiO2 Thin Films. Acs Applied Materials & Interfaces 2009, 1, 1013-1022.
    [Bibtex]
    @Article{Hamers43,
    Title = {Photochemical Grafting and Patterning of Biomolecular Layers onto TiO2 Thin Films},
    Author = {Li, B. and Franking, R. and Landis, E. C. and Kim, H. and Hamers, R. J.},
    Journal = {Acs Applied Materials \& Interfaces},
    Year = {2009},
    Note = {Li, Bo Franking, Ryan Landis, Elizabeth C. Kim, Heesuk Hamers, Robert J.},
    Number = {5},
    Pages = {1013-1022},
    Volume = {1},
    Abstract = {TiO2 thin films are highly stable and can be deposited onto a wide variety of substrate materials under moderate conditions. We demonstrate that organic alkenes will graft to the surface of TiO2 when illuminated with UV light at 254 nm and that the resulting layers provide a starting point for the preparation of DNA-modified TiO2 thin films exhibiting excellent stability and biomolecular selectivity. By using alkenes with a protected amino group at the distal end, the grafted layers can be deprotected to yield molecular layers with exposed primary amino groups that can then be used to covalently link DNA oligonucleotides to the TiO2 surface. We demonstrate that the resulting DNA-modified surfaces exhibit excellent selectivity toward complementary versus noncomplementary target sequences in solution and that the surfaces can withstand 25 cycles of hybridization and denaturation in 8.3 M urea with little or no degradation. Furthermore, the use of simple masking methods provides a way to directly control the spatial location of the grafted layers, thereby providing a way to photopattern the spatial distribution of biologically active molecules to the TiO2 surfaces. Using Ti films ranging from 10 to 100 nm in thickness allows the preparation of TiO2 films that range from highly reflective to almost completely transparent; in both cases, the photochemical grafting of alkenes can be used as a starting point for stable surfaces with good biomolecular recognition properties.},
    Doi = {10.1021/am900001h},
    ISSN = {1944-8244},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000268665200007
    http://pubs.acs.org/doi/abs/10.1021/am900001h}
    }
  • [DOI] Marcus, M. S., J. M. Simmons, S. E. Baker, R. J. Hamers, and M. A. Eriksson. Predicting the Results of Chemical Vapor Deposition Growth of Suspended Carbon Nanotubes. Nano Letters 2009, 9, 1806-1811.
    [Bibtex]
    @Article{Hamers44,
    Title = {Predicting the Results of Chemical Vapor Deposition Growth of Suspended Carbon Nanotubes},
    Author = {Marcus, M. S. and Simmons, J. M. and Baker, S. E. and Hamers, R. J. and Eriksson, M. A.},
    Journal = {Nano Letters},
    Year = {2009},
    Note = {Marcus, Matthew S. Simmons, Jason M. Baker, Sarah E. Hamers, Robert J. Eriksson, Mark A.},
    Number = {5},
    Pages = {1806-1811},
    Volume = {9},
    Abstract = {The successful growth of suspended carbon nanotubes is normally based on purely empirical results. Here we demonstrate the ability to predict the successful suspension of nanotubes across a range of trench widths by combining experimental growth data with a theoretical description of nanotube mechanics at the growth temperature. We show that rare thermal oscillations much larger than the rms amplitude combined with the large nanotube-substrate adhesion energy together are responsible for unsuccessful nanotube suspensions. We derive an upper limit on the number of deleterious nanotube-substrate interactions that can be tolerated before successful growth becomes impossible, and we are able to accurately explain literature reports of suspended nanotube growth. The methodology developed here should enable improved growth yields of suspended nanotubes, and it provides a framework in which to analyze the role of nanotube-substrate interactions during nanotube growth by chemical vapor deposition.},
    Doi = {10.1021/nl803726b},
    ISSN = {1530-6984},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000266157100014
    http://pubs.acs.org/doi/abs/10.1021/nl803726b}
    }
  • [DOI] Metz, K. M., A. N. Mangham, M. J. Bierman, S. Jin, R. J. Hamers, and J. A. Pedersen. Engineered Nanomaterial Transformation under Oxidative Environmental Conditions: Development of an in vitro Biomimetic Assay. Environmental Science & Technology 2009, 43, 1598-1604.
    [Bibtex]
    @Article{Hamers45,
    Title = {Engineered Nanomaterial Transformation under Oxidative Environmental Conditions: Development of an in vitro Biomimetic Assay},
    Author = {Metz, K. M. and Mangham, A. N. and Bierman, M. J. and Jin, S. and Hamers, R. J. and Pedersen, J. A.},
    Journal = {Environmental Science \& Technology},
    Year = {2009},
    Note = {Metz, Kevin M. Mangham, Andrew N. Bierman, Matthew J. Jin, Song Hamers, Robert J. Pedersen, Joel A.},
    Number = {5},
    Pages = {1598-1604},
    Volume = {43},
    Abstract = {Once released into the environment, engineered nanomaterials may be transformed by microbially mediated redox processes altering their toxicity and fate. Little information currently exists on engineered nanomaterial transformation under environmentally relevant conditions. Here, we report the development of an in vitro biomimetic assay for investigation of nanomaterial transformation under simulated oxidative environmental conditions. The assay is based on the extracellular hydroquinone-driven Fenton's reaction used by lignolytic fungi. We demonstrate the utility of the assay using CdSe(core)/ZnS(shell) quantum dots (QDs) functionalized with poly(ethylene glycol). GO transformation was assessed by UV-visible spectroscopy, inductively coupled plasma-optical emission spectroscopy, dynamic light scattering, transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX). ON were readily degraded under simulated oxidative environmental conditions: the ZnS shell eroded and cadmium was released from the CID core, TEM, electron diffraction analysis, and EDX of transformed QDs revealed formation of amorphous Se aggregates. The biomimetic hydroquinone-driven Fenton's reaction degraded QDs to a larger extent than did H(2)O(2) and classical Fenton's reagent (H(2)O(2) + Fe(2+)). This assay provides a new method to characterize transformations of nanoscale materials expected to occur under oxidative environmental conditions.},
    Doi = {10.1021/es802217y},
    ISSN = {0013-936X},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000263758600061
    http://pubs.acs.org/doi/abs/10.1021/es802217y}
    }
  • [DOI] King-Heiden, T. C., P. N. Wiecinski, A. N. Mangham, K. M. Metz, D. Nesbit, J. A. Pedersen, R. J. Hamers, W. Heideman, and R. E. Peterson. Quantum Dot Nanotoxicity Assessment Using the Zebrafish Embryo. Environmental Science & Technology 2009, 43, 1605-1611.
    [Bibtex]
    @Article{Hamers46,
    Title = {Quantum Dot Nanotoxicity Assessment Using the Zebrafish Embryo},
    Author = {King-Heiden, T. C. and Wiecinski, P. N. and Mangham, A. N. and Metz, K. M. and Nesbit, D. and Pedersen, J. A. and Hamers, R. J. and Heideman, W. and Peterson, R. E.},
    Journal = {Environmental Science \& Technology},
    Year = {2009},
    Note = {King-Heiden, Tisha C. Wiecinski, Paige N. Mangham, Andrew N. Metz, Kevin M. Nesbit, Dorothy Pedersen, Joel A. Hamers, Robert J. Heideman, Warren Peterson, Richard E.},
    Number = {5},
    Pages = {1605-1611},
    Volume = {43},
    Abstract = {Quantum dots (QDS) hold promise for several biomedical, life sciences, and photovoltaic applications. Substantial production volumes and environmental release are anticipated. CID toxicity may be intrinsic to their physicochemical properties, or result from the release of toxic components during breakdown. We hypothesized that developing zebrafish could be used to identify and distinguish these different types of toxicity, Embryos were exposed to aqueous suspensions of CdSe(core)/ZnS(shell) QDs functionalized with either poly-L-lysine or poly(ethylene glycol) terminated with methoxy, carboxylate, or amine groups, Toxicity was influenced by the CID coating, which also contributed to the QD suspension stability. At sublethal concentrations, many QD preparations produced characteristic signs of Cd toxicity that weakly correlated with metallothionein expression, indicating that QDs are only slightly degraded in vivo. QDs also produced distinctly different toxicity that could not be explained by Cd release. Using the zebrafish model, we were able to distinguish toxicity intrinsic to QDs from that caused by released metal ions. We conclude that developing zebrafish provide a rapid, low-cost approach for assessing structure-toxicity relationships of nanoparticles.},
    Doi = {10.1021/es801925c},
    ISSN = {0013-936X},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000263758600062}
    }
  • [DOI] Landis, E. C. and R. J. Hamers. Covalent Grafting of Redox-Active Molecules to Vertically Aligned Carbon Nanofiber Arrays via "Click" Chemistry. Chemistry of Materials 2009, 21, 724-730.
    [Bibtex]
    @Article{Hamers47,
    Title = {Covalent Grafting of Redox-Active Molecules to Vertically Aligned Carbon Nanofiber Arrays via "Click" Chemistry},
    Author = {Landis, E. C. and Hamers, R. J.},
    Journal = {Chemistry of Materials},
    Year = {2009},
    Note = {Landis, Elizabeth C. Hamers, Robert J.},
    Number = {4},
    Pages = {724-730},
    Volume = {21},
    Abstract = {Electrochemically active ferrocene groups were covalently linked to vertically aligned carbon nanofibers (VACNFs) in a simple and efficient manner via the Cu(I)-catalyzed azide alkyne cycloaddition (CuAAC), one form of "click" chemistry. The VACNFs were terminated with azide groups followed by the attachment of ethynylferrocene through a 1,4-disubstituted 1,2,3-triazole linkage. Our results show that the CuAAC reaction goes to completion in one hour and provides highly stable attachment of electrochemically active ferrocene groups to the nanofibers. X-ray photoelectron spectroscopy measurements of the density of surface-bound ferrocene molecules are in good agreement with those determined by cyclic voltammetry. The rates of electron transfer were found to be slightly faster than those measured previously through alkyl linkages to the VACNF surface. Stability tests show that the covalently grafted ferrocene groups are stable for more than 1500 repeated cyclic voltammograms and over a potential window of > 1.5 V, limited by the solvent. These results suggest that the use of "click" chemistry with VACNFs provides a facile route toward synthesis of high-surface-area electrodes with high stability and tailored electrochemical properties.},
    Doi = {10.1021/cm802869b},
    ISSN = {0897-4756},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000263431600019
    http://pubs.acs.org/doi/abs/10.1021/cm802869b}
    }
  • [DOI] Colavita, P. E., B. Sun, X. Y. Wang, and R. J. Hamers. Influence of Surface Termination and Electronic Structure on the Photochemical Grafting of Alkenes to Carbon Surfaces. Journal of Physical Chemistry C 2009, 113, 1526-1535.
    [Bibtex]
    @Article{Hamers48,
    Title = {Influence of Surface Termination and Electronic Structure on the Photochemical Grafting of Alkenes to Carbon Surfaces},
    Author = {Colavita, P. E. and Sun, B. and Wang, X. Y. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2009},
    Note = {Colavita, Paula E. Sun, Bin Wang, Xiaoyu Hamers, Robert J.},
    Number = {4},
    Pages = {1526-1535},
    Volume = {113},
    Abstract = {The ultraviolet-initiated photochemical grafting of n-alkenes to surfaces of amorphous carbon, diamond, and carbon nanofibers has recently emerged as a way to impart new surface properties to these materials. Recent studies have shown that grafting on these materials is initiated by a novel photoelectron ejection process, evidenced by a strong dependence of reaction efficiency on the electron affinity of the reactant molecules. Yet, the role of different surface functional groups and the resulting changes in valence band density of states and surface work function have not been determined previously. Understanding the influence of surface carbonyl groups is particularly significant because C=O groups increase the surface work function but are also known to catalyze certain electron-transfer processes at carbon surfaces. Here, we use infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), and ultraviolet photoelectron spectroscopy (UPS) to investigate how changes in surface termination (H-termination vs O-termination) and surface annealing impact the valence electronic structure and work function of the samples, and how these changes influence the grafting of alkenes to the surfaces. Four different n-alkenes bearing terminal groups were used in order to identify the role of the molecular electron affinity, using alkenes terminated with -NHCOCF(3), -NHCOO(tert-butyl), -COOMe, and -CH(3) groups. By using narrowly spaced interdigitated electrodes of amorphous carbon, we are able to directly detect the UV-induced photoemission. Our results show that O-termination of amorphous carbon surfaces enhances the photochemical grafting yield compared with H-termination of surfaces, contrary to what has been found on diamond surfaces. Surfaces annealed to increase the amount of sp(2)-hybridized carbon, and therefore being most metallic in character, have the highest reactivity. The changes in reactivity are explained in terms of the changes in valence electronic structure of the samples and the influence of oxygen on the photoelectron emission process that initiates the grafting reaction.},
    Doi = {10.1021/jp805933h},
    ISSN = {1932-7447},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000262665600054
    http://pubs.acs.org/doi/abs/10.1021/jp805933h}
    }
  • [DOI] Morin, S. A., Y. H. La, C. C. Liu, J. A. Streifer, R. J. Hamers, P. F. Nealey, and S. Jin. Assembly of Nanocrystal Arrays by Block-Copolymer-Directed Nucleation. Angewandte Chemie-International Edition 2009, 48, 2135-2139.
    [Bibtex]
    @Article{Hamers49,
    Title = {Assembly of Nanocrystal Arrays by Block-Copolymer-Directed Nucleation},
    Author = {Morin, S. A. and La, Y. H. and Liu, C. C. and Streifer, J. A. and Hamers, R. J. and Nealey, P. F. and Jin, S.},
    Journal = {Angewandte Chemie-International Edition},
    Year = {2009},
    Note = {Morin, Stephen A. La, Young-Hye Liu, Chi-Chum Streifer, Jeremy A. Hamers, Robert J. Nealey, Paul F. Jin, Song},
    Number = {12},
    Pages = {2135-2139},
    Volume = {48},
    Doi = {10.1002/anie.200805471},
    ISSN = {1433-7851},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000264411800017}
    }
  • [DOI] Smith, C. I., A. Bowfield, M. C. Cuquerella, C. P. Mansley, T. Farrell, P. Harrison, D. S. Martin, D. G. Fernig, C. Edwards, J. E. Butler, R. J. Hamers, B. Sun, X. Wang, and P. Weightman. Detection of DNA hybridisation on a functionalised diamond surface using reflection anisotropy spectroscopy. Europhysics Letters 2009, 85, 18006.
    [Bibtex]
    @Article{Hamers50,
    Title = {Detection of DNA hybridisation on a functionalised diamond surface using reflection anisotropy spectroscopy},
    Author = {Smith, C. I. and Bowfield, A. and Cuquerella, M. C. and Mansley, C. P. and Farrell, T. and Harrison, P. and Martin, D. S. and Fernig, D. G. and Edwards, C. and Butler, J. E. and Hamers, R. J. and Sun, B. and Wang, X. and Weightman, P.},
    Journal = {Europhysics Letters},
    Year = {2009},
    Note = {Smith, C. I. Bowfield, A. Cuquerella, M. C. Mansley, C. P. Farrell, T. Harrison, P. Martin, D. S. Fernig, D. G. Edwards, C. Butler, J. E. Hamers, R. J. Sun, B. Wang, X. Weightman, P.},
    Number = {85},
    Pages = {18006},
    Volume = {85},
    Abstract = {The analysis of single-stranded DNA attached to a polycrystalline diamond surface by reflection anisotropy spectroscopy (RAS) demonstrates that the DNA is oriented essentially vertically to the surface. RAS is able to detect the hybridisation between the attached strand and the homologous sequence. Copyright (C) EPLA, 2009},
    Doi = {18006
    10.1209/0295-5075/85/18006},
    ISSN = {0295-5075},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000263692500038}
    }
  • [DOI] Wiecinski, P. N., K. M. Metz, A. N. Mangham, K. H. Jacobson, R. J. Hamers, and J. A. Pedersen. Gastrointestinal biodurability of engineered nanoparticles: Development of an in vitro assay. Nanotoxicology 2009, 3, 202-U66.
    [Bibtex]
    @Article{Hamers51,
    Title = {Gastrointestinal biodurability of engineered nanoparticles: Development of an in vitro assay},
    Author = {Wiecinski, P. N. and Metz, K. M. and Mangham, A. N. and Jacobson, K. H. and Hamers, R. J. and Pedersen, J. A.},
    Journal = {Nanotoxicology},
    Year = {2009},
    Note = {Wiecinski, Paige N. Metz, Kevin M. Mangham, Andrew N. Jacobson, Kurt H. Hamers, Robert J. Pedersen, Joel A.},
    Number = {3},
    Pages = {202-U66},
    Volume = {3},
    Abstract = {The toxicity of engineered nanoparticles is expected to depend in part on their stability in biological systems. To assess the biodurability of engineered nanomaterials in the human digestive system, we adapted an in vitro assay previously used to evaluate the bioaccessibility of metals in contaminated soils. The compositions of the simulated gastric and intestinal fluids, temperature and residence times were designed to closely mimic conditions in the stomach and duodenum of the small intestine. We demonstrated the utility of the assay using CdSe(core)/ZnS(shell) quantum dots functionalized with polyethylene glycol (PEG) thiol of two different molecular masses (PEG(350) and PEG(5000)). Under gastric conditions, removal of the PEG ligand diminished the stability of PEG(350)-quantum dot suspensions, while PEG(5000)-quantum dots were severely degraded. Inclusion of the glycoprotein mucin, but not the digestive protein pepsin, in simulated gastric fluids provided both PEG(350)-and PEG(5000)-coated quantum dots partial protection from transformations induced by gastric conditions.},
    Doi = {10.1080/17435390902859556},
    ISSN = {1743-5390},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000274526400007
    http://informahealthcare.com/doi/abs/10.1080/17435390902859556}
    }

2008

  • Colavita, Paula E., Bin Sun, Kiu-Yuen Tse, and Robert J. Hamers. Photo-induced surface functionalization of carbon surfaces: The role of photoelectron ejection. Journal of Vacuum Science & Technology A 2008, 26, 925-931.
    [Bibtex]
    @Article{Hamers457,
    Title = {Photo-induced surface functionalization of carbon surfaces: The role of photoelectron ejection},
    Author = {Colavita, Paula E. and Sun, Bin and Tse, Kiu-Yuen and Hamers, Robert J.},
    Journal = {Journal of Vacuum Science \& Technology A},
    Year = {2008},
    Note = {English
    Article
    0734-2101},
    Number = {4},
    Pages = {925-931},
    Volume = {26},
    Abstract = {Carbon-based materials are attractive for a wide range of applications, from biomaterials to fuel cells; however, their effective use often requires controlling the surface chemistry to incorporate recognition moieties or reactive centers. The high stability of carbon also makes it a challenging material to functionalize; recently, the use of ultraviolet light (254 nm) to initiate functionalization of carbon surfaces has emerged as a way to obtain carbon/organic interfaces. with tailored properties. The authors have investigated the mechanism of covalent grafting of amorphous carbon surfaces with functional organic molecules using the photochemical reaction of terminal alkenes. Measurements comparing the reactivity of different n-alkenes bearing different terminal groups at the terminus opposite the olefin showed pronounced differences in reactivity. They characterized the rate and final coverage of the resulting organic layers using x-ray photoelectron spectroscopy and infrared reflection-absorption spectroscopy. Ultraviolet photoelectron spectroscopy and photocurrent measurements suggested that the reaction involves photoelectron emission from the carbon surface into the liquid phase. Density functional calculations show a strong correlation between the electron affinity of the alkenes and the observed reactivity. The specific terminal group opposite to the olefin was found to play an important role in the stabilization of excess negative charges on the molecule, thus explaining the strong dependence of reactivity on the particular terminal group. These findings suggest that the reaction involves injection of photoelectrons into the alkene acceptor levels, leading to the formation of radical anions in the liquid phase. Finally, the authors demonstrate that the grafting of marginally reactive alkenes can be enhanced by seeding the surface with a small amount of good electron accepting groups. These results provide fundamental new insights into the role of electronic excitations in controlling rates and mechanisms of olefin reactions at surfaces. While demonstrated here for amorphous carbon, these results may also be significant for the UV initiated grafting of olefins on other semiconductors. (C) 2008 American Vacuum Society.},
    Keywords = {Dissociative electron-transfer
    hydrogen-terminated diamond
    irradiated
    single-crystals
    atomic-force microscopy
    photochemical
    functionalization
    thin-films
    reductive cleavage
    diazonium salts
    glassy-carbon
    electrochemical reduction
    Materials Science, Coatings & Films
    Physics, Applied},
    Type = {Journal Article}
    }
  • [DOI] Kang, Huiman, Francois A. Detcheverry, Andrew N. Mangham, Mark P. Stoykovich, Kostas Ch Daoulas, Robert J. Hamers, Marcus Mueller, Juan J. de Pablo, and Paul F. Nealey. Hierarchical assembly of nanoparticle superstructures from block copolymer-nanoparticle composites. Physical Review Letters 2008, 100, .
    [Bibtex]
    @Article{Hamers460,
    Title = {Hierarchical assembly of nanoparticle superstructures from block copolymer-nanoparticle composites},
    Author = {Kang, Huiman and Detcheverry, Francois A. and Mangham, Andrew N. and Stoykovich, Mark P. and Daoulas, Kostas Ch and Hamers, Robert J. and Mueller, Marcus and de Pablo, Juan J. and Nealey, Paul F.},
    Journal = {Physical Review Letters},
    Year = {2008},
    Note = {English
    Article
    0031-9007},
    Number = {14},
    Volume = {100},
    Abstract = {We investigate the assembly of block copolymer-nanoparticle composite films on chemically nanopatterned substrates and present fully three-dimensional simulations of a coarse grain model for these hybrid systems. The location and distribution of nanoparticles within the ordered block copolymer domains depends on the thermodynamic state of the composite in equilibrium with the surface. Hierarchical assembly of nanoparticles enables applications in which the ability to precisely control their locations within periodic and nonregular geometry patterns and arrays is required.},
    Doi = {148303},
    Keywords = {Arrays
    nanostructures
    nanocrystals
    organization
    mixtures
    domains
    blends
    growth
    films
    gold
    Physics, Multidisciplinary},
    Type = {Journal Article}
    }
  • Paoprasert, P., B. Park, H. Kim, P. Colavita, R. J. Hamers, P. G. Evans, and P. Gopalan. Dipolar Chromophore Functional Layers in Organic Field Effect Transistors. Advanced Materials 2008, 20, 4180-+.
    [Bibtex]
    @Article{Hamers52,
    Title = {Dipolar Chromophore Functional Layers in Organic Field Effect Transistors},
    Author = {Paoprasert, P. and Park, B. and Kim, H. and Colavita, P. and Hamers, R. J. and Evans, P. G. and Gopalan, P.},
    Journal = {Advanced Materials},
    Year = {2008},
    Note = {Paoprasert, Peerasak Park, Byoungnam Kim, Heesuk Colavita, Paula Hamers, Robert J. Evans, Paul G. Gopalan, Padma},
    Number = {21},
    Pages = {4180-+},
    Volume = {20},
    Abstract = {A layer of functionalized disperse red 19 (DR19) chromophore molecules leads to novel reversible photoelectrical characteristics in organic thin film field effect transistor. Photoassisted poling, along with the change in the dipole of the DR19 under illumination, and photoinduced charge transfer to electron traps in the DR19 layer combine to change the threshold voltage of transistors by up to 100 V.},
    ISSN = {0935-9648},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000261040000033}
    }
  • [DOI] Landis, E. C. and R. J. Hamers. Covalent Grafting of Ferrocene to Vertically Aligned Carbon Nanofibers: Electron-transfer Processes at Nanostructured Electrodes. Journal of Physical Chemistry C 2008, 112, 16910-16918.
    [Bibtex]
    @Article{Hamers53,
    Title = {Covalent Grafting of Ferrocene to Vertically Aligned Carbon Nanofibers: Electron-transfer Processes at Nanostructured Electrodes},
    Author = {Landis, E. C. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2008},
    Note = {Landis, Elizabeth C. Hamers, Robert J.},
    Number = {43},
    Pages = {16910-16918},
    Volume = {112},
    Abstract = {Ferrocene was used as a model system to understand the electron-transfer properties of redox-active molecules covalently linked to the surface of vertically aligned carbon nanofibers. Ultraviolet-initiated grafting of organic alkenes was used to prepare carboxylic acid-terminated layers, and ferrocene was then linked to these layers via amide groups. The electrical properties of the resulting layers were measured Using cyclic voltammetry and electrochemical impedance spectroscopy. Standard rate constants for electron transfer (k(app)) of approximately 1.0-1.3 s(-1) were found for ferrocene covalently linked to the nanofiber surfaces, compared to about 3 s(-1) on glassy carbon surfaces. Measurements of the electron-transfer rates through molecular layers of different length show no significant change. Similarly, no significant changes were observed in electron-transfer rate constants or peak width upon dilution of the ferrocene-containing molecules. Our results show that molecular layers grafted to carbon nanofibers are sparse and disordered compared with those commonly studied on planar surfaces. A model based on preferential grafting to exposed graphitic edge planes is proposed to explain the results.},
    Doi = {10.1021/jp806173d},
    ISSN = {1932-7447},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000260357800029
    http://pubs.acs.org/doi/pdfplus/10.1021/jp806173d}
    }
  • [DOI] Hamers, R. J.. Nanotechnology – Diamonds are for tethers. Nature 2008, 454, 708-709.
    [Bibtex]
    @Article{Hamers54,
    Title = {Nanotechnology - Diamonds are for tethers},
    Author = {Hamers, R. J.},
    Journal = {Nature},
    Year = {2008},
    Note = {Hamers, Robert J.},
    Number = {7205},
    Pages = {708-709},
    Volume = {454},
    Doi = {10.1038/454708a},
    ISSN = {0028-0836},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000258228000031}
    }
  • [DOI] Kim, H., P. E. Colavita, P. Paoprasert, P. Gopalan, T. F. Kuech, and R. J. Hamers. Grafting of molecular layers to oxidized gallium nitride surfaces via phosphonic acid linkages. Surface Science 2008, 602, 2382-2388.
    [Bibtex]
    @Article{Hamers55,
    Title = {Grafting of molecular layers to oxidized gallium nitride surfaces via phosphonic acid linkages},
    Author = {Kim, H. and Colavita, P. E. and Paoprasert, P. and Gopalan, P. and Kuech, T. F. and Hamers, R. J.},
    Journal = {Surface Science},
    Year = {2008},
    Note = {Kim, Heesuk Colavita, Paula E. Paoprasert, Peerasak Gopalan, Padma Kuech, T. F. Hamers, Robert J.},
    Number = {14},
    Pages = {2382-2388},
    Volume = {602},
    Abstract = {The grafting of organophosphonic acids to the oxidized GaN(0001) surface was investigated using X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. The stability of the monolayers was characterized by immersion in buffer solutions at pH 5, pH 7, and pH 9 for one week. The results demonstrate excellent stability under acidic and neutral conditions, but decreased stability under basic conditions. While photochemical grafting of alkenes directly to the unoxidized GaN surface appears to provide slightly better stability under basic conditions, the versatility of phosphonic acids makes this approach a potentially attractive alternative method for integrating molecular and/or biomolecular layers with GaN and other wide-bandgap semiconductors. (C) 2008 Elsevier B.V. All rights reserved.},
    Doi = {10.1016/j.susc.2008.05.002},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000259062200015
    http://www.sciencedirect.com/science/article/pii/S0039602808003063}
    }
  • [DOI] Lockett, M. R., S. C. Weibel, M. F. Phillips, M. R. Shortreed, B. Sun, R. M. Corn, R. J. Hamers, F. Cerrina, and L. M. Smith. Carbon-on-metal films for surface plasmon resonance detection of DNA arrays. Journal of the American Chemical Society 2008, 130, 8611-+.
    [Bibtex]
    @Article{Hamers56,
    Title = {Carbon-on-metal films for surface plasmon resonance detection of DNA arrays},
    Author = {Lockett, M. R. and Weibel, S. C. and Phillips, M. F. and Shortreed, M. R. and Sun, B. and Corn, R. M. and Hamers, R. J. and Cerrina, F. and Smith, L. M.},
    Journal = {Journal of the American Chemical Society},
    Year = {2008},
    Note = {Lockett, Matthew R. Weibel, Stephen C. Phillips, Margaret F. Shortreed, Michael R. Sun, Bin Corn, Robert M. Hamers, Robert J. Cerrina, Franco Smith, Lloyd M.},
    Number = {27},
    Pages = {8611-+},
    Volume = {130},
    Abstract = {Surface plasmon resonance (SPR) imaging affords label-free monitoring of biomolecule interactions in an array format. A surface plasmon conducting metal thin film is required for SPR measurements. Gold thin films are traditionally used in SPR experiments as they are readily functionalized with thiol-containing molecules through formation of a gold-sulfur bond. The lability of this gold-thiol linkage upon exposure to oxidizing conditions and ultraviolet light renders these surfaces incompatible with light-directed synthetic methods for fabricating DNA arrays. It is shown here that applying a thin carbon overlayer to the gold surface yields a chemically robust substrate that permits light-directed synthesis and also supports surface plasmons. DNA arrays fabricated on these carbon-metal substrates are used to analyze two classes of biomolecular interactions: DNA-DNA and DNA-protein. This new strategy allows the combinatorial study of binding interactions directly from native, unmodified biomolecules of interest and offers the possibility of discovering new ligands in complex mixtures such as cell lysates.},
    Doi = {10.1021/ja802454c},
    ISSN = {0002-7863},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000257358300022
    http://pubs.acs.org/doi/pdfplus/10.1021/ja802454c}
    }
  • [DOI] Li, B., L. Shang, M. S. Marcus, T. L. Clare, E. Perkins, and R. J. Hamers. Chemoselective nanowire fuses: Chemically induced cleavage and electrical, detection of carbon nanofiber bridges. Small 2008, 4, 795-801.
    [Bibtex]
    @Article{Hamers58,
    Title = {Chemoselective nanowire fuses: Chemically induced cleavage and electrical, detection of carbon nanofiber bridges},
    Author = {Li, B. and Shang, L. and Marcus, M. S. and Clare, T. L. and Perkins, E. and Hamers, R. J.},
    Journal = {Small},
    Year = {2008},
    Note = {Li, Bo Shang, Lu Marcus, Matthew S. Clare, Tarni Lasseter Perkins, Edward Hamers, Robert J.},
    Number = {6},
    Pages = {795-801},
    Volume = {4},
    Abstract = {A new type of nanoscale bioswitch based on the electrical detection of chemically induced cleavage of chemical bonds, which bind individual nanowires across a pair of electrodes is demonstrated. Carbon nanofibers are manipulated using dielectrophoresis to form single-nanowire bridges across microelectrode junctions, and are anchored through a biomolecular interaction. Once in place, chemically induced cleavage of a recognition site along the bonds linking the nanowire to the electrodes allows the nanowire to be easily removed by a flow of fluid; this removal can be detected in real time via changes in the AC electrical response. This form of sensing is inherently digital in nature as the removal of a single nanowire produces a sudden decrease in the current between electrodes and is essentially a chemoselective fuse. These results suggest that this sensing principle could be a general method for digital chemical and/or biological sensing using individual nanowires.},
    Doi = {10.1002/smll.200700944},
    ISSN = {1613-6810},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000257549100018
    http://onlinelibrary.wiley.com/store/10.1002/smll.200700944/asset/795_ftp.pdf?v=1&t=hak6994x&s=1671a8100c10a0deef0cf68d6a92eb08769eb3af}
    }
  • [DOI] Beck, J. D., L. Shang, B. Li, M. S. Marcus, and R. J. Hamers. Discrimination between Bacillus species by impedance analysis of individual dielectrophoretically positioned spores. Analytical Chemistry 2008, 80, 3757-3761.
    [Bibtex]
    @Article{Hamers59,
    Title = {Discrimination between Bacillus species by impedance analysis of individual dielectrophoretically positioned spores},
    Author = {Beck, J. D. and Shang, L. and Li, B. and Marcus, M. S. and Hamers, R. J.},
    Journal = {Analytical Chemistry},
    Year = {2008},
    Note = {Beck, Joseph D. Shang, Lu Li, Bo Marcus, Matthew S. Hamers, Robert J.},
    Number = {10},
    Pages = {3757-3761},
    Volume = {80},
    Abstract = {We combine the use of dielectrophoretic positioning with electrical impedance measurements to detect and discriminate between individual bacterial spores on the basis of their electrical response. Using lithographically defined microelectrodes, we use dielectrophoresis to manipulate individual bacterial spores between the electrodes. The introduction of a single spore between the microelectrodes produces a significant change in electrical response that is species-dependent. When positioned between two electrodes and an AC voltage was applied, single spores caused current increases averaging 6.8 (+/- 2.4) pA for Bacillus mycoides to 1.18 (+/- 0.37) pA for Bacillus licheniformis. Using a mixture of spores of two different species, we demonstrate the ability to distinguish the species of individual spores in real time. This work demonstrates the feasibility of using impedance measurements for real-time detection and discrimination between different types of spores.},
    Doi = {10.1021/ac702113t},
    ISSN = {0003-2700},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000255871500031
    http://pubs.acs.org/doi/pdfplus/10.1021/ac702113t}
    }
  • [DOI] Seo, S., L. C. Grabow, M. Mavrikakis, R. J. Hamers, N. J. Thompson, and P. G. Evans. Molecular-scale structural distortion near vacancies in pentacene. Applied Physics Letters 2008, 92, .
    [Bibtex]
    @Article{Hamers60,
    Title = {Molecular-scale structural distortion near vacancies in pentacene},
    Author = {Seo, S. and Grabow, L. C. and Mavrikakis, M. and Hamers, R. J. and Thompson, N. J. and Evans, P. G.},
    Journal = {Applied Physics Letters},
    Year = {2008},
    Note = {Seo, S. Grabow, L. C. Mavrikakis, M. Hamers, R. J. Thompson, N. J. Evans, P. G.},
    Number = {15},
    Volume = {92},
    Abstract = {Molecular vacancies form in both of the crystallographic basis sites of thin pentacene crystals. Features in scanning tunneling microscopy images of these crystals correspond to the exposed terminal atoms of molecules. The (001) and (00 (1) over bar) surfaces of pentacene are distinguishable, which allows for the identification of the absolute orientation of crystals and for the unambiguous assignment of the position of molecules relative to each vacancy. For vacancies in each molecular basis site of the pentacene (001) surface, the image feature associated with one molecular nearest neighbor is displaced by significantly more than other molecules. (c) 2008 American Institute of Physics.},
    Doi = {153313
    10.1063/1.2913687},
    ISSN = {0003-6951},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000255117100105
    http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=APPLAB000092000015153313000001&idtype=cvips&doi=10.1063/1.2913687&prog=normal}
    }
  • [DOI] Colavita, P. E., J. A. Streifer, B. Sun, X. Y. Wang, P. Warf, and R. J. Hamers. Enhancement of photochemical grafting of terminal alkenes at surfaces via molecular mediators: The role of surface-bound electron acceptors. Journal of Physical Chemistry C 2008, 112, 5102-5112.
    [Bibtex]
    @Article{Hamers68,
    Title = {Enhancement of photochemical grafting of terminal alkenes at surfaces via molecular mediators: The role of surface-bound electron acceptors},
    Author = {Colavita, P. E. and Streifer, J. A. and Sun, B. and Wang, X. Y. and Warf, P. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2008},
    Note = {Colavita, Paula E. Streifer, Jeremy A. Sun, Bin Wang, Xiaoyu Warf, Patrick Hamers, Robert J.},
    Number = {13},
    Pages = {5102-5112},
    Volume = {112},
    Abstract = {The use of ultraviolet light to functionalize the surface of carbon-based materials with terminal alkenes has emerged as a way to overcome the high chemical stability of these surfaces to create functional interfaces. It was previously shown that surface-bound trifluoroacetic acid protected 10-aminodec-1-ene (TFAAD) can be used to promote the grafting of unreactive alkenes using 254 nm light, but the mechanism by which this enhancement occurs was not understood. Here, we present a detailed study of how surface-bound TFAAD enhances the grafting of organic molecules to the surface of hydrogen-terminated amorphous carbon. Infrared reflection absorption spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy experiments show that pregrafting TFAAD onto carbon surfaces greatly enhances the subsequent grafting of 1-dodecene, dodecane and dodecane-d(26) by locally facilitating photoemission of electrons. Using a photopatterned TFAAD "seed" layer, we demonstrate that subsequent grafting of these hydrocarbons is enhanced in regions immediately adjacent to the seed and proceeds almost exclusively parallel to the carbon surface. The roles of liquid-phase radical species, valence band holes, and the photochemical fragmentation of surface species in controlling the overall reaction mechanism are discussed.},
    Doi = {10.1021/jp711167n},
    ISSN = {1932-7447},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000254541000046
    http://pubs.acs.org/doi/pdfplus/10.1021/jp711167n}
    }
  • [DOI] Hamers, R. J.. 2008. Formation and Characterization of Organic Monolayers on Semiconductor Surfaces. In Annual Review of Analytical Chemistry, .
    [Bibtex]
    @InBook{Hamers69,
    Title = {Formation and Characterization of Organic Monolayers on Semiconductor Surfaces},
    Author = {Hamers, R. J.},
    Pages = {707-736},
    Year = {2008},
    Note = {Hamers, Robert J.},
    Series = {Annual Review of Analytical Chemistry},
    Type = {Book Section},
    Volume = {1},
    Abstract = {Organic-semiconductor interfaces are playing increasingly important roles in fields ranging from electronics to nanotechnology, to biosensing. The continuing decrease in microelectronic device feature sizes is raising an especially great interest in understanding how to integrate molecular systems with conventional, inorganic microelectronic materials, particularly silicon. The explosion of interest in the biological sciences has provided further impetus for learning how to integrate biological molecules and systems with microelectronics to form true bioelectronic systems. Organic monolayers present an excellent opportunity for surmounting many of the practical barriers that have hindered the full integration of microelectronics technology with organic and biological systems. Of all the semiconductor materials, silicon and diamond stand out as unique. This review focuses upon the preparation and characterization of organic and biomolecular layers Oil semiconductor surfaces, with special emphasis oil monolayers C tined oil silicon and diamond.},
    Booktitle = {Annual Review of Analytical Chemistry},
    Doi = {10.1146/annurev.anchem.1.031207.112916},
    ISBN = {1936-1327
    978-0-8243-4401-6},
    Url = {<Go to ISI>://WOS:000262525200024}
    }

2007

  • Colavita, Paula E., Bin Sun, Kiu-Yuen Tse, and Robert J. Hamers. Photochemical grafting of n-alkenes onto carbon surfaces: the role of photoelectron ejection. Journal of the American Chemical Society 2007, 129, 13554-13565.
    [Bibtex]
    @Article{Hamers438,
    Title = {Photochemical grafting of n-alkenes onto carbon surfaces: the role of photoelectron ejection},
    Author = {Colavita, Paula E. and Sun, Bin and Tse, Kiu-Yuen and Hamers, Robert J.},
    Journal = {Journal of the American Chemical Society},
    Year = {2007},
    Note = {English
    Article
    0002-7863},
    Number = {44},
    Pages = {13554-13565},
    Volume = {129},
    Abstract = {The grafting of molecular layers to carbon-based materials provides a way to combine the high chemical and thermal stability of these materials with surface properties such as chemical recognition or reactivity. The functionalization of surfaces with ultraviolet light has emerged as a way to modify difficult-to-functionalize materials, such as diamond. We have performed a combined experimental and computational investigation of the photochemical reaction of terminal alkenes with hydrogen-terminated carbon surfaces. 1 -Alkenes carrying various terminal functional groups (-NHCOCF3, -NHCOO(tert-butyl), -COOCH3, -CH3) were grafted from the neat liquids using 254 nm light. These layers were characterized using X-ray Photoelectron Spectroscopy and Infrared Reflectance Absorption Spectroscopy. Pronounced differences in reactivity were observed between the molecules: trifluoroacetamide-terminated alkenes grafted the fastest and yielded self-terminating layers after similar to 4 h. Ultraviolet photoelectron spectroscopy and photocurrent measurements show that the grafting reaction involves photoemission of electrons into the liquid. Density functional calculations show that the reactivites of the four molecules are correlated with their electron affinities, with the trifluoroacetamide group acting as the best electron acceptor and having the highest reactivity. Our results demonstrate that photoejection of electrons from the solid into the acceptor levels of the alkenes initiates the functionalization reaction and controls the overall rate. Finally, marginally reactive n-alkenes were induced to react and form dense monolayers by seeding the carbon surface with small amounts of a good electron acceptor, such as the trifluoroacetamide moiety. This study provides important new mechanistic insights into the use of ultraviolet light to initiate grafting of alkenes onto surfaces.},
    Keywords = {Hydrogen-terminated diamond
    negative-electron-affinity
    irradiated
    single-crystals
    thin-films
    amorphous-carbon
    semiconductor
    electrodes
    reductive cleavage
    radical cations
    gas-phase
    alkyl
    monolayers
    Chemistry, Multidisciplinary},
    Type = {Journal Article}
    }
  • Dementiev, Viacheslav V., Robert C. West, Robert J. Hamers, and Kiu-Yuen Tse. 2007. Electrochemical double-layer capacitor using organosilicon electrolytes. .
    [Bibtex]
    @Misc{Hamers439,
    Title = {Electrochemical double-layer capacitor using organosilicon electrolytes},
    Author = {Dementiev, Viacheslav V. and West, Robert C. and Hamers, Robert J. and Tse, Kiu-Yuen},
    Year = {2007},
    Journal = {Conference Name},
    Type = {Conference}
    }
  • Kang, Huiman, Andrew N. Mangham, Mark P. Stoykovich, Robert J. Hamers, and Paul F. Nealey. Fabrication of nanoparticle arrays using directed assembly of block copolymers. Polymer Preprints (American Chemical Society, Division of Polymer Chemistry) 2007, 48, 886-887.
    [Bibtex]
    @Article{Hamers442,
    Title = {Fabrication of nanoparticle arrays using directed assembly of block copolymers},
    Author = {Kang, Huiman and Mangham, Andrew N. and Stoykovich, Mark P. and Hamers, Robert J. and Nealey, Paul F.},
    Journal = {Polymer Preprints (American Chemical Society, Division of Polymer Chemistry)},
    Year = {2007},
    Note = {37
    Plastics Manufacture and Processing
    Department of Chemical and Biological Engineering and Center for Nanotechnology,University of Wisconsin,Madison,WI,USA.
    Journal; Computer Optical Disk
    0032-3934
    written in English.
    1) Sohn, B; J Mater Chem 2002, 12, 1730|2) La, Y; Nano Letters 2005, 5, 1379|3) Chiu, J; JACS 2005, 127, 5036|4) Lin, Y; Nature 2005, 434, 55|5) Kim, S; Nature 2003, 424, 411|6) Stoykovich, M; Science 2005, 308, 1442|7) Peng, Z; JACS 2002, 124, 3343|8) Edwards, E; Adv Mater 2004, 16, 1315},
    Number = {1},
    Pages = {886-887},
    Volume = {48},
    Type = {Journal Article}
    }
  • [DOI] Trewyn, B. G., II Slowing, S. Giri, H. T. Chen, and V. S. Y. Lin. Synthesis and functionalization of a mesoporous silica nanoparticle based on the sol-gel process and applications in controlled release. Accounts of Chemical Research 2007, 40, 846-853.
    [Bibtex]
    @Article{Hamers539,
    Title = {Synthesis and functionalization of a mesoporous silica nanoparticle based on the sol-gel process and applications in controlled release},
    Author = {Trewyn, B. G. and Slowing, II and Giri, S. and Chen, H. T. and Lin, V. S. Y.},
    Journal = {Accounts of Chemical Research},
    Year = {2007},
    Note = {ISI Document Delivery No.: 212PY
    Times Cited: 320
    Cited Reference Count: 27
    Trewyn, Brian G. Slowing, Igor I. Giri, Supratim Chen, Hung-Ting Lin, Victor S. -Y.
    Amer chemical soc
    Washington},
    Number = {9},
    Pages = {846-853},
    Volume = {40},
    Abstract = {Mesoporous silica nanoparticles (MSNs) are introduced as chemically and thermally stable nanomaterials with well-defined and controllable morphology and porosity. It is shown that these particles possess external and internal surfaces that can be selectively functionalized with multiple organic and inorganic groups. On the basis of these characteristics, the biocompatibility of silica, and their efficient uptake by mammalian cells, MSNs are proposed as the basis of nanodevices for the controlled release of drugs and genes into living cells.},
    Doi = {10.1021/ar600032u},
    ISSN = {0001-4842},
    Keywords = {responsive controlled-release
    molecular-sieves
    delivery-system
    organic functionalization
    neurotransmitters
    morphology
    cells},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000249610500015}
    }
  • [DOI] Park, B., P. Paoprasert, I. In, J. Zwickey, P. E. Colavita, R. J. Hamers, P. Gopalan, and P. G. Evans. Functional self-assembled monolayers for optimized photoinduced charge transfer in organic field effect transistors. Advanced Materials 2007, 19, 4353-+.
    [Bibtex]
    @Article{Hamers70,
    Title = {Functional self-assembled monolayers for optimized photoinduced charge transfer in organic field effect transistors},
    Author = {Park, B. and Paoprasert, P. and In, I. and Zwickey, J. and Colavita, P. E. and Hamers, R. J. and Gopalan, P. and Evans, P. G.},
    Journal = {Advanced Materials},
    Year = {2007},
    Note = {Park, Byoungnam Paoprasert, Peerasak In, Insik Zwickey, Jodi Colavita, Paida E. Hamers, Robert J. Gopalan, Padma Evans, Paid G.},
    Number = {24},
    Pages = {4353-+},
    Volume = {19},
    Abstract = {[GRAPHICS] A C-60-terminated self assembled monolayer at the semiconductor/gate insulator interface of an organic thin film field effect transistor provides acceptor states optimized for photoinduced charge transfer. Charge densities of up to 10(13) charges cm(-2) can be trapped in the C-60 acceptors.},
    Doi = {10.1002/adma.200602875},
    ISSN = {0935-9648},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000252511500010
    http://onlinelibrary.wiley.com/store/10.1002/adma.200602875/asset/4353_ftp.pdf?v=1&t=hak68u94&s=7860e1e3ae53a80ce216cc7ed3fd13454306ae6f}
    }
  • [DOI] Amos, F. F., S. A. Morin, J. A. Streifer, R. J. Hamers, and S. Jin. Photodetector arrays directly assembled onto polymer substrates from aqueous solution. Journal of the American Chemical Society 2007, 129, 14296-14302.
    [Bibtex]
    @Article{Hamers71,
    Title = {Photodetector arrays directly assembled onto polymer substrates from aqueous solution},
    Author = {Amos, F. F. and Morin, S. A. and Streifer, J. A. and Hamers, R. J. and Jin, S.},
    Journal = {Journal of the American Chemical Society},
    Year = {2007},
    Note = {Amos, Fairland F. Morin, Stephen A. Streifer, Jeremy A. Hamers, Robert J. Jin, Song},
    Number = {46},
    Pages = {14296-14302},
    Volume = {129},
    Abstract = {We report a simple and inexpensive approach to directly assemble arrays of cadmium sulfide (CdS) semiconductors onto transparent flexible poly(ethylene terephthalate) (PET) sheets via a polymer-mediated selective nucleation and growth process from an aqueous solution. This strategy of assembling functional materials onto plastics utilizes the surface functional molecules of the UV photooxidation patterned polymer to direct the nucleation and growth of CdS. We demonstrated that Such assembled structures are viable for flexible macroelectronics, as manifested by the fabrication of CdS photodetector arrays on PET that can withstand bending. The best devices exhibited a specific detectivity of 3 x 10(11) cm Hz(1/2) W-1 dat 514-nm excitation wavelength at a modulation frequency of 90 Hz at room temperature. This direct assembly strategy eliminates additional lithography and etching steps during the deposition of the active inorganic semiconductor layer, is general to other inorganic materials and plastic substrates, and can enable low-cost, wearable, and/or disposable flexible electronics.},
    Doi = {10.1021/ja073675b},
    ISSN = {0002-7863},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000251182000054
    http://pubs.acs.org/doi/pdfplus/10.1021/ja073675b}
    }
  • [DOI] Tse, K. Y., L. Z. Zhang, S. E. Baker, B. M. Nichols, R. West, and R. J. Hamers. Vertically aligned carbon nanofibers coupled with organosilicon electrolytes: Electrical properties of a high-stability nanostructured electrochemical interface. Chemistry of Materials 2007, 19, 5734-5741.
    [Bibtex]
    @Article{Hamers72,
    Title = {Vertically aligned carbon nanofibers coupled with organosilicon electrolytes: Electrical properties of a high-stability nanostructured electrochemical interface},
    Author = {Tse, K. Y. and Zhang, L. Z. and Baker, S. E. and Nichols, B. M. and West, R. and Hamers, R. J.},
    Journal = {Chemistry of Materials},
    Year = {2007},
    Note = {Tse, Kiu-Yuen Zhang, Lingzhi Baker, Sarah E. Nichols, Beth M. West, Robert Hamers, Robert J.},
    Number = {23},
    Pages = {5734-5741},
    Volume = {19},
    Abstract = {Organosilicon compounds can form novel electrolytes having a number of unusual properties, including high electrochemical stability, high thermal stability, and low viscosity. Vertically aligned carbon nanofibers can act as exceptionally good nanostructured electrodes, with the vertical orientation and,presence of edge-plane graphite along the sidewalls providing desirable electrochemical properties. We have explored the electrical properties of the interfaces of VACNF electrodes with a model organosilicon electrolyte solution. The compound 1-(3-{2-[2-(2-methoxy-ethoxy)-ethoxyl]-ethoxyl}-propyl)-1,1,3,3,3-pentamethyl-disiloxane (2SM3) with added lithium bis-oxalato-borate (LiBOB) was used. Forests of vertically aligned carbon nanofibers (VACNFs) similar to 80 nm in diameter grown by plasma-enhanced chemical vapor deposition (PECVD) were used as electrodes. Our results show that the resulting interfaces yield interfacial capacitances equal to the increase in geometric area, indicating full electrochemical accessibility of the nanofiber sidewalls. Measurements as a function of potential perfect stability at applied voltages up to 3.5 V. Some initial Faradaic reactions arise near 3.5 V, but these decrease within a few cycles to produce interfaces that exhibit excellent stability up to 5 V while yielding > 1000 mu F/cm(2) from nanofibers only 2 mu m long. The results show that the organosilicon electrolyte combined with VACNFs provides excellent electrochemical properties. The results have implications for understanding the ability to integrate organosilicon electrolytes with high-surface-area carbon materials for applications such as electrochemical double-layer capacitors and lithium-ion batteries.},
    Doi = {10.1021/cm0714842},
    ISSN = {0897-4756},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000250803900037
    http://pubs.acs.org/doi/pdfplus/10.1021/cm0714842}
    }
  • [DOI] Weidkamp, K. P., R. M. Tromp, and R. J. Hamers. Epitaxial growth of large pentacene crystals on Si(001) surfaces functionalized with molecular monolayers. Journal of Physical Chemistry C 2007, 111, 16489-16497.
    [Bibtex]
    @Article{Hamers73,
    Title = {Epitaxial growth of large pentacene crystals on Si(001) surfaces functionalized with molecular monolayers},
    Author = {Weidkamp, K. P. and Tromp, R. M. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2007},
    Note = {Weidkamp, Kevin P. Tromp, Rudolf M. Hamers, Robert J.},
    Number = {44},
    Pages = {16489-16497},
    Volume = {111},
    Abstract = {The nucleation and growth of pentacene thin films are controlled largely by the energies associated with the interfaces. We have used low-energy electron microscopy (LEEM) and photoemission electron microscopy (PEEM) to investigate the nucleation and growth of pentacene thin films on Si(001) surfaces modified with two different molecular monolayers. Clean Si(001)-(2 x 1) surfaces were modified with either 1,5cyclooctadiene or 1-dodecene prior to pentacene growth to study the effects of exposed pi bonds at the interface, orientation of those pi bonds relative to each other, and rigidity of the molecular layer on pentacene nucleation, growth, and crystalline orientation. Both molecular monolayers weaken the substrate - pentacene interaction sufficiently to allow for low pentacene nucleation density and good pentacene diffusion, leading to the growth of pentacene grains as large as 100 mu m. Pentacene grows epitaxially on both functionalized surfaces, adopting an orthorhombic unit cell that follows the orientation of the underlying Si surface reconstruction. Our results show that in addition to improving the ultimate size of pentacene crystals, molecular monolayers are able to impose the substrate orientation on pentacene nuclei and thereby control the crystalline orientation of the thin film.},
    Doi = {10.1021/jp074560x},
    ISSN = {1932-7447},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000250647000059
    http://pubs.acs.org/doi/pdfplus/10.1021/jp074560x}
    }
  • [DOI] Wang, X., P. E. Colavita, K. M. Metz, J. E. Butler, and R. J. Hamers. Direct photopatterning and SEM Imaging of molecular monolayers on diamond surfaces: Mechanistic insights into UV-Initiated molecular grafting. Langmuir 2007, 23, 11623-11630.
    [Bibtex]
    @Article{Hamers75,
    Title = {Direct photopatterning and SEM Imaging of molecular monolayers on diamond surfaces: Mechanistic insights into UV-Initiated molecular grafting},
    Author = {Wang, X. and Colavita, P. E. and Metz, K. M. and Butler, J. E. and Hamers, R. J.},
    Journal = {Langmuir},
    Year = {2007},
    Note = {Wang, Xiaoyu Colavita, Paula E. Metz, Kevin M. Butler, James E. Hamers, Robert J.},
    Number = {23},
    Pages = {11623-11630},
    Volume = {23},
    Abstract = {We have used X-ray photoelectron spectroscopy (XPS), infrared reflection-absorption spectroscopy, and field-emission scanning electron microscopy (SEM) to investigate the formation of single- and two-component molecular patterns by direct photochemical grafting of alkenes onto hydrogen-terminated diamond surfaces using sub-band gap 254 nm ultraviolet light. Trifluoroacetamide-protected 1-aminodec-1-ene (TFAAD) and 1-dodecene were used as model systems for grafting. Illumination with sub-band gap light can induce several different kinds of excitations, including creation of mobile electrons and holes in the bulk and creation of radicals at the surface and in the adjacent fluid, which induce grafting of the alkenes to the surface. SEM images of patterned molecular layers on nanocrystalline diamond surfaces reveal sharp transitions between functionalized and nonfunctionalized regions consistent with diffraction-limited excitation. However, identical experiments on type IIb single-crystal diamond yield a significantly more extended transition region in the molecular pattern. These data imply that the spatial resolution of the direct molecular photopatterning is affected by diffusion of charge carriers in the bulk of the diamond samples. The molecular contrast between surfaces with different terminations is consistent with the expected trends in molecular electron affinity. These results provide new mechanistic insights into the direct patterning and imaging of molecular monolayers on surfaces.},
    Doi = {10.1021/la701803g},
    ISSN = {0743-7463},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000250584500047
    http://pubs.acs.org/doi/pdfplus/10.1021/la701803g}
    }
  • [DOI] Stuen, K. O., I. In, E. Han, J. A. Streifer, R. J. Hamers, P. F. Nealey, and P. Gopalan. Imaging layers for the directed assembly of block copolymer films: Dependence of the physical and chemical properties of patterned polymer brushes on brush molecular weight. Journal of Vacuum Science & Technology B 2007, 25, 1958-1962.
    [Bibtex]
    @Article{Hamers76,
    Title = {Imaging layers for the directed assembly of block copolymer films: Dependence of the physical and chemical properties of patterned polymer brushes on brush molecular weight},
    Author = {Stuen, K. O. and In, I. and Han, E. and Streifer, J. A. and Hamers, R. J. and Nealey, P. F. and Gopalan, P.},
    Journal = {Journal of Vacuum Science \& Technology B},
    Year = {2007},
    Note = {Stuen, K. O. In, I. Han, E. Streifer, J. A. Hamers, R. J. Nealey, P. F. Gopalan, P.
    51st International Conference on Electron, Ion, and Photon Beam Technology and Nanofabrication
    May 29-jun 01, 2007
    Denver, CO},
    Number = {6},
    Pages = {1958-1962},
    Volume = {25},
    Abstract = {The directed assembly of polystyrene-block-poly(methyl methacrylate) films using chemically nanopatterned polymer brush surfaces with various molecular weights was investigated. The brushes (3-10 nm in thickness) were made from polystyrene that was end grafted to silicon wafers and patterned to have 40-60 nm period stripes consisting of unmodified polymer and polymer that was subjected to brief oxygen plasma. The best assembly of block copolymer films was achieved using brushes with molecular weights of 3 kg/mol or less. The brushes were analyzed by goniometry, infrared reflection-absorption spectroscopy, x-ray photoelectron spectroscopy, and ellipsometry. The brush thickness increased nonlinearly with molecular weight and the high molecular weight brushes reconstructed under solvent and thermal annealing. The lower molecular weight brushes form the best imaging layers due to their optimum thickness that provides uniform surface coverage and prevents reconstruction of the film surface. The thin brushes ensure contact between the block copolymer and the hydrophilic groups in the modified regions of the brush during annealing, maximizing the effective interfacial energy contrast and the driving force for perfect directed assembly. (c) 2007 American Vacuum Society.},
    Doi = {10.1116/1.2799970},
    ISSN = {1071-1023},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000251611900035
    http://avspublications.org/jvstb/resource/1/jvtbd9/v25/i6/p1958_s1
    http://avspublications.org/jvstb/resource/1/jvtbd9/v25/i6/p1958_s1?isAuthorized=no}
    }
  • [DOI] Marcus, M. S., L. Shang, B. Li, J. A. Streifer, J. D. Beck, E. Perkins, M. A. Eriksson, and R. J. Hamers. Dielectrophoretic manipulation and real-time electrical detection of single-nanowire bridges in aqueous saline solutions. Small 2007, 3, 1610-1617.
    [Bibtex]
    @Article{Hamers77,
    Title = {Dielectrophoretic manipulation and real-time electrical detection of single-nanowire bridges in aqueous saline solutions},
    Author = {Marcus, M. S. and Shang, L. and Li, B. and Streifer, J. A. and Beck, J. D. and Perkins, E. and Eriksson, M. A. and Hamers, R. J.},
    Journal = {Small},
    Year = {2007},
    Note = {Marcus, Matthew S. Shang, Lu Li, Bo Streifer, Jeremy A. Beck, Joseph D. Perkins, Edward Eriksson, Mark A. Hamers, Robert J.},
    Number = {9},
    Pages = {1610-1617},
    Volume = {3},
    Abstract = {Dielectrophoretic manipulation of nanoscale materials is typically performed in nonionic, highly insulating solvents. However, biomolecular recognition processes, such as DNA hybridization and protein binding, typically operate in highly conducting, aqueous saline solutions. Here, we report investigations of the manipulation and real-time detection of individual nanowires bridging microelectrode gaps in saline solutions. Measurements of the electrode impedance versus frequency show a crossover in behavior at a critical frequency that is dependent on the ionic strength. We demonstrate that by operating above this critical frequency, it is possible to use dielectrophoresis to manipulate nanowires across electrode gaps in saline solutions. By using electrical ground planes and nulling schemes to reduce the background currents, we further demonstrate the ability to electrically detect bridging and unbridging events of individual nanowires in saline solutions. The ability to both manipulate and detect bridging events with electrical signals provides a pathway toward automated assembly of nanoscale devices that incorporate biomolecular recognition elements.},
    Doi = {10.1002/smll.200700130},
    ISSN = {1613-6810},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000249490800025
    http://onlinelibrary.wiley.com/store/10.1002/smll.200700130/asset/1610_ftp.pdf?v=1&t=hak68lif&s=c98f1b28d256473e2ffb5677bc4fe9022d0cf83b}
    }
  • [DOI] Sun, B., S. E. Baker, J. E. Butler, H. Kim, J. N. Russell, L. Shang, K. Y. Tse, W. S. Yang, and R. J. Hamers. Covalent molecular functionalization of diamond thin-film transistors. Diamond and Related Materials 2007, 16, 1608-1615.
    [Bibtex]
    @Article{Hamers80,
    Title = {Covalent molecular functionalization of diamond thin-film transistors},
    Author = {Sun, B. and Baker, S. E. and Butler, J. E. and Kim, H. and Russell, J. N. and Shang, L. and Tse, K. Y. and Yang, W. S. and Hamers, R. J.},
    Journal = {Diamond and Related Materials},
    Year = {2007},
    Note = {Sun, Bin Baker, Sarah E. Butler, James E. Kim, Heesuk Russell, John N., Jr. Shang, Lu Tse, Kiu-Yuen Yang, Wensha Hamers, Robert J.},
    Number = {8},
    Pages = {1608-1615},
    Volume = {16},
    Abstract = {The chemical functionalization and the resulting electrical properties of diamond thin-film transistors (TFTs) modified with organic monolayer films have been explored. Chemical processing steps were developed to produce amine-terminated surfaces in a manner compatible with preexisting front-surface metal contacts and dielectric protecting layers. The electrical properties of the monolayer-modified TFTs fabricated using different procedures were investigated. Interchanging the order of the functionalization and contact deposition steps changes the devices transconductance by a factor of 100. Electrical measurements of thin-film transistor devices with three different molecular terminating groups show significant changes in threshold voltage that correspond with the expected charges of the functional groups. (c) 2007 Published by Elsevier B.V.},
    Doi = {10.1016/j.diamond.2007.02.004},
    ISSN = {0925-9635},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000247804900024
    http://www.sciencedirect.com/science/article/pii/S0925963507001707}
    }
  • [DOI] Metz, K. M., D. Goel, and R. J. Hamers. Molecular monolayers enhance the formation of electrocatalytic platinum nanoparticles on vertically aligned carbon nanofiber scaffolds. Journal of Physical Chemistry C 2007, 111, 7260-7265.
    [Bibtex]
    @Article{Hamers81,
    Title = {Molecular monolayers enhance the formation of electrocatalytic platinum nanoparticles on vertically aligned carbon nanofiber scaffolds},
    Author = {Metz, K. M. and Goel, D. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry C},
    Year = {2007},
    Note = {Metz, Kevin M. Goel, Divya Hamers, Robert J.},
    Number = {20},
    Pages = {7260-7265},
    Volume = {111},
    Abstract = {We demonstrate the use of molecular monolayers to enhance the nucleation of electrocatalytically active platinum nanocrystals onto vertically aligned carbon nanofiber (VACNF) scaffolds. The photochemical functionalization of VACNFs with bifunctional organic alkenes produces monolayer-modified VACNFs exposing large amounts of carboxylic acid groups. Subsequent electroless deposition of platinum leads to high densities of similar to 8 nm diameter Pt nanocrystals uniformly deposited along the length of the nanofibers. Electrochemical measurements show that the molecular monolayers do not impede redox behavior of the electrode, and measurements of the electrocatalytic oxidation of methanol show very high catalytic efficiency. Our results suggest that the use of molecular functionalization layers provides an improved way to integrate nanostructured carbon with metals for a variety of catalytic and electrocatalytic applications.},
    Doi = {10.1021/jp070102c},
    ISSN = {1932-7447},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000246569800006
    http://pubs.acs.org/doi/pdfplus/10.1021/jp070102c}
    }
  • [DOI] Peng, W. N., M. M. Roberts, E. P. Nordberg, F. S. Flack, P. E. Colavita, R. J. Hamers, D. E. Savage, M. G. Lagally, and M. A. Eriksson. Single-crystal silicon/silicon dioxide multilayer heterostructures based on nanomembrane transfer. Applied Physics Letters 2007, 90, .
    [Bibtex]
    @Article{Hamers82,
    Title = {Single-crystal silicon/silicon dioxide multilayer heterostructures based on nanomembrane transfer},
    Author = {Peng, W. N. and Roberts, M. M. and Nordberg, E. P. and Flack, F. S. and Colavita, P. E. and Hamers, R. J. and Savage, D. E. and Lagally, M. G. and Eriksson, M. A.},
    Journal = {Applied Physics Letters},
    Year = {2007},
    Note = {Peng, Weina Roberts, Michelle M. Nordberg, Eric P. Flack, Frank S. Colavita, Paula E. Hamers, Robert J. Savage, Donald E. Lagally, Max G. Eriksson, Mark A.},
    Number = {18},
    Volume = {90},
    Abstract = {A method to fabricate single-crystal Si/SiO2 multilayer heterostructures is presented. Heterostructures are fabricated by repeated transfer of single crystal silicon nanomembranes alternating with deposition of spin-on-glass. Nanomembrane transfer produces multilayers with low surface roughness and smooth interfaces. To demonstrate interface quality, the specular reflectivities of one-, two-, and three-membrane heterostructures are measured. Comparison of the measured reflectivity with theoretical calculations shows good agreement. Nanomembrane stacking allows for the preprocessing of individual membranes with a high thermal budget before the low thermal budget assembly of the stack, suggesting a new avenue for the three dimensional integration of integrated circuits. (c) 2007 American Institute of Physics.},
    Doi = {183107
    10.1063/1.2734367},
    ISSN = {0003-6951},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000246210000109
    http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=APPLAB000090000018183107000001&idtype=cvips&doi=10.1063/1.2734367&prog=normal}
    }
  • [DOI] Schwartz, M. P. and R. J. Hamers. Reaction of acetonitrile with the silicon(001) surface: A combined XPS and FTIR study. Surface Science 2007, 601, 945-953.
    [Bibtex]
    @Article{Hamers88,
    Title = {Reaction of acetonitrile with the silicon(001) surface: A combined XPS and FTIR study},
    Author = {Schwartz, M. P. and Hamers, R. J.},
    Journal = {Surface Science},
    Year = {2007},
    Note = {Schwartz, Michael P. Hamers, Robert J.},
    Number = {4},
    Pages = {945-953},
    Volume = {601},
    Abstract = {The adsorption of acetonitrile on the Si(0 0 1) surface has been investigated using X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR). XPS and FTIR spectra indicate that adsorbed acetonitrile forms two correlated binding configurations, a C=N species with a strong FTIR absorption at 1540 cm(-1) and a C=C=N (ketenimine) species that has a very strong FTIR absorption at 1952 cm(-1). The C=C=N FTIR peak at 1952 cm-1 shows a striking polarization dependence, with the infrared transition dipole almost entirely in the plane of the sample and parallel to the Si=Si dimer axis. Our data suggests that the primary C=C=N structure results from cleavage of two C-H bonds, forming a structure in which the N and terminal C atom are both linked to the surface. Temperature-dependent experiments help to elucidate the complicated reaction mechanism for acetonitrile adsorbing onto the Si(001) surface. Dosing at higher temperature increases the amount of C=C=N relative to C=N species while heating leads to direct transformation of the C=N to the C=C=N species. Our results indicate that previous studies, which considered only products formed by cleavage of a single C-H bond, have misidentified the primary kentenimine product. A reinterpretation of the earlier results, combined with data presented here, sheds new light onto the products and mechanism of interaction of acetonitrile with Si(001). (c) 2006 Elsevier B.V. All rights reserved.},
    Doi = {10.1016/j.susc.2006.11.035},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000245155800013
    http://www.sciencedirect.com/science/article/pii/S0039602806011940}
    }
  • [DOI] Yang, W. S., J. E. Butler, J. N. Russell, and R. J. Hamers. Direct electrical detection of antigen-antibody binding on diamond and silicon substrates using electrical impedance spectroscopy. Analyst 2007, 132, 296-306.
    [Bibtex]
    @Article{Hamers89,
    Title = {Direct electrical detection of antigen-antibody binding on diamond and silicon substrates using electrical impedance spectroscopy},
    Author = {Yang, W. S. and Butler, J. E. and Russell, J. N. and Hamers, R. J.},
    Journal = {Analyst},
    Year = {2007},
    Note = {Yang, Wensha Butler, James E. Russell, John N., Jr. Hamers, Robert J.},
    Number = {4},
    Pages = {296-306},
    Volume = {132},
    Abstract = {The integration of biological molecules with semiconducting materials such as silicon and diamond has great potential for the development of new types of bioelectronic devices, such as biosensors and bioactuators. We have investigated the electrical properties of the antibody antigen modified diamond and silicon surfaces using electrical impedance spectroscopy ( EIS). Frequency dependent measurements at the open-circuit potential show: ( a) significant changes in impedance at frequency > 10(4) Hz when the surface immobilized IgG was exposed to anti-IgG, and (b) only little or no change when exposed to anti-IgM. Mott-Schottky measurements at high frequency ( 200 kHz) show that the impedance is dominated by the space charge layer of the semiconducting substrates. Silicon surfaces modified in a similar manner to the diamond surface are compared; n-type and p-type samples show complementary behavior, as expected for a field effect. We also show it is possible to directly observe antigen - antibody interaction at a fixed frequency in real time, and with no additional labeling.},
    Doi = {10.1039/b612201a},
    ISSN = {0003-2654},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000245241200003
    http://pubs.rsc.org/en/content/articlepdf/2007/an/b612201a}
    }

2006

  • [DOI] Simmons, J. M., B. M. Nichols, S. E. Baker, M. S. Marcus, O. M. Castellini, C. S. Lee, R. J. Hamers, and M. A. Eriksson. Effect of ozone oxidation on single-walled carbon nanotubes. Journal of Physical Chemistry B 2006, 110, 7113-7118.
    [Bibtex]
    @Article{Hamers100,
    Title = {Effect of ozone oxidation on single-walled carbon nanotubes},
    Author = {Simmons, J. M. and Nichols, B. M. and Baker, S. E. and Marcus, M. S. and Castellini, O. M. and Lee, C. S. and Hamers, R. J. and Eriksson, M. A.},
    Journal = {Journal of Physical Chemistry B},
    Year = {2006},
    Note = {Simmons, JM Nichols, BM Baker, SE Marcus, MS Castellini, OM Lee, CS Hamers, RJ Eriksson, MA},
    Number = {14},
    Pages = {7113-7118},
    Volume = {110},
    Abstract = {Exposing single-walled carbon nanotubes to room-temperature UV-generated ozone leads to an irreversible increase in their electrical resistance. We demonstrate that the increased resistance is due to ozone oxidation on the sidewalls of the nanotubes rather than at the end caps. Raman and X-ray photoelectron spectroscopies show an increase in the defect density due to the oxidation of the nanotubes. Using ultraviolet photoelectron spectroscopy, we show that these defects represent the removal of pi-conjugated electron states near the Fermi level, leading to the observed increase in electrical resistance. Oxidation of carbon nanotubes is an important first step in many chemical functionalization processes. Because the oxidation rate can be controlled with short exposures, UV-generated ozone offers the potential for use as a low-thermal-budget processing tool.},
    Doi = {10.1021/jp0548422},
    ISSN = {1520-6106},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000236772900007
    http://pubs.acs.org/doi/pdfplus/10.1021/jp0548422}
    }
  • [DOI] Baker, S. E., K. Y. Tse, C. S. Lee, and R. J. Hamers. Fabrication and characterization of vertically aligned carbon nanofiber electrodes for biosensing applications. Diamond and Related Materials 2006, 15, 433-439.
    [Bibtex]
    @Article{Hamers104,
    Title = {Fabrication and characterization of vertically aligned carbon nanofiber electrodes for biosensing applications},
    Author = {Baker, S. E. and Tse, K. Y. and Lee, C. S. and Hamers, R. J.},
    Journal = {Diamond and Related Materials},
    Year = {2006},
    Note = {Baker, SE Tse, KY Lee, CS Hamers, RJ
    8th Applied Diamond Conference/NanoCarbon
    May 15-19, 2005
    Chicago, IL},
    Number = {2-3},
    Pages = {433-439},
    Volume = {15},
    Abstract = {We describe recent experiments aimed at using carbon nanofibers for biosensing applications. Vertically aligned carbon nanofibers are grown on molybdenum electrodes to provide electrical contact to the nanofibers. Upon exposure to electrolyte solutions, we find that short nanofibers of < 1 mu m length can be wet and dried without significant mechanical disruption. However, longer fibers are prone to clumping due to meniscus forces. Deposition of SiO2 adds mechanical strength and electrically insulates the nanofiber sidewalls, which can be further augmented by additional deposition of epoxy-based photoresist. Reactive-ion etching re-exposes the carbon core, localizing the electrical response to the nanofiber ends and leading to electrically active electrodes of similar to 40 nm radius. Measurements of the diffusion-limited current from ensembles of nanofibers are solutions containing redox agents are in excellent agreement with classical electrochemical theory. We also briefly describe the use of chemical and electrochemical methods to functionalize carbon nanofibers. (c) 2005 Elsevier B.V. All rights reserved.},
    Doi = {10.1016/j.diamond.2005.08.019},
    ISSN = {0925-9635},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000236440300050
    http://www.sciencedirect.com/science/article/pii/S0925963505003353}
    }
  • Cao, X. P., S. K. Coulter, M. D. Ellison, H. B. Liu, J. M. Liu, and R. J. Hamers. Bonding of nitrogen-containing organic molecules to the silicon(001) surface: The role of aromaticity. Journal of Physical Chemistry B 2006, 15, 433-439.
    [Bibtex]
    @Article{Hamers422,
    Title = {Bonding of nitrogen-containing organic molecules to the silicon(001) surface: The role of aromaticity},
    Author = {Cao, X. P. and Coulter, S. K. and Ellison, M. D. and Liu, H. B. and Liu, J. M. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {2006},
    Note = {ELSEVIER SCIENCE SA, PO BOX 564, 1001 LAUSANNE, SWITZERLAND. URL: http://www.elsevier.nl},
    Number = {2-3},
    Pages = {433-439},
    Volume = {15},
    Keywords = {Applied Physics/Condensed Matter/Materials Science in Current
    Contents(R)/Physical, Chemical & Earth Sciences. Materials Science
    & Engineering in Current Contents(R)/Engineering, Computing &
    Technology.},
    Type = {Journal Article}
    }
  • Hamers, Robert J., Sarah Baker, and Chang-Soo Lee. 2006. Methods for the production of sensor arrays using electrically addressable electrodes. (Wisconsin Alumni Research Foundation, USA)..
    [Bibtex]
    @Misc{Hamers428,
    Title = {Methods for the production of sensor arrays using electrically addressable electrodes},
    Author = {Hamers, Robert J. and Baker, Sarah and Lee, Chang-Soo},
    Year = {2006},
    Journal = {Conference Name},
    Publisher = {(Wisconsin Alumni Research Foundation, USA).},
    Type = {Conference}
    }
  • Hamers, Robert J. and Joseph D. Beck. 2006. Apparatus for transport and analysis of particles using dielectrophoresis. (USA)..
    [Bibtex]
    @Misc{Hamers429,
    Title = {Apparatus for transport and analysis of particles using dielectrophoresis},
    Author = {Hamers, Robert J. and Beck, Joseph D.},
    Year = {2006},
    Journal = {Conference Name},
    Publisher = {(USA).},
    Type = {Conference}
    }
  • Hamers, R. J.. Nanotubes and Nanowires (book review). Journal of the American Chemical Society 2006, 2, 902.
    [Bibtex]
    @Article{Hamers537,
    Title = {Nanotubes and Nanowires (book review)},
    Author = {Hamers, R. J.},
    Journal = {Journal of the American Chemical Society},
    Year = {2006},
    Pages = {902},
    Volume = {2},
    Type = {Journal Article}
    }
  • [DOI] Metz, K. M., K. Y. Tse, S. E. Baker, E. C. Landis, and R. J. Hamers. Ultrahigh-surface-area metallic electrodes by templated electroless deposition on functionalized carbon nanofiber scaffolds. Chemistry of Materials 2006, 18, 5398-5400.
    [Bibtex]
    @Article{Hamers90,
    Title = {Ultrahigh-surface-area metallic electrodes by templated electroless deposition on functionalized carbon nanofiber scaffolds},
    Author = {Metz, K. M. and Tse, K. Y. and Baker, S. E. and Landis, E. C. and Hamers, R. J.},
    Journal = {Chemistry of Materials},
    Year = {2006},
    Note = {Metz, Kevin M. Tse, Kiu-Yuen Baker, Sarah E. Landis, Elizabeth C. Hamers, Robert J.},
    Number = {23},
    Pages = {5398-5400},
    Volume = {18},
    Doi = {10.1021/cm061563y},
    ISSN = {0897-4756},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000241808600004
    http://pubs.acs.org/doi/pdfplus/10.1021/cm061563y}
    }
  • [DOI] Sun, B., P. E. Colavita, H. Kim, M. Lockett, M. S. Marcus, L. M. Smith, and R. J. Hamers. Covalent photochemical functionalization of amorphous carbon thin films for integrated real-time biosensing. Langmuir 2006, 22, 9598-9605.
    [Bibtex]
    @Article{Hamers91,
    Title = {Covalent photochemical functionalization of amorphous carbon thin films for integrated real-time biosensing},
    Author = {Sun, B. and Colavita, P. E. and Kim, H. and Lockett, M. and Marcus, M. S. and Smith, L. M. and Hamers, R. J.},
    Journal = {Langmuir},
    Year = {2006},
    Note = {Sun, Bin Colavita, Paula E. Kim, Heesuk Lockett, Matthew Marcus, Matthew S. Smith, Lloyd M. Hamers, Robert J.},
    Number = {23},
    Pages = {9598-9605},
    Volume = {22},
    Abstract = {Recent studies have demonstrated that carbon, in the form of diamond, can be functionalized with molecular and/or biomolecular species to yield interfaces exhibiting extremely high stability and selectivity in binding to target biomolecules in solution. However, diamond and most other crystalline forms of carbon involve high-temperature deposition or processing steps that restrict their ability to be integrated with other materials. Here, we demonstrate that photochemical functionalization of amorphous carbon films followed by covalent immobilization of DNA yields highly stable surfaces with excellent biomolecular recognition properties that can be used for real-time biological detection. Carbon films deposited onto substrates at 300 K were functionalized with organic alkenes bearing protected amine groups and characterized using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The functionalized carbon surfaces were covalently linked to DNA oligonucleotides. Measurements show very high selectivity for binding to the complementary sequence, and a high density of hybridizing DNA molecules. Samples repeatedly hybridized and denatured 25 times showed no significant degradation. The ability to use amorphous carbon films as a basis for real-time biosensing is demonstrated by coating quartz crystal microbalance (QCM) crystals with a thin carbon film and using this for covalent modification with DNA. Measurements of the resonance frequency show the ability to detect DNA hybridization in real time with a detection limit of < 3% of a monolayer, with a high degree of reversibility. These results demonstrate that functionalized films of amorphous carbon can be used as a chemically stable platform for integrated biosensing using only room-temperature processing steps.},
    Doi = {10.1021/la061749b},
    ISSN = {0743-7463},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000241669800023
    http://pubs.acs.org/doi/pdfplus/10.1021/la061749b}
    }
  • [DOI] Marcus, M. S., J. M. Simmons, O. M. Castellini, R. J. Hamers, and M. A. Eriksson. Photogating carbon nanotube transistors. Journal of Applied Physics 2006, 100, .
    [Bibtex]
    @Article{Hamers92,
    Title = {Photogating carbon nanotube transistors},
    Author = {Marcus, M. S. and Simmons, J. M. and Castellini, O. M. and Hamers, R. J. and Eriksson, M. A.},
    Journal = {Journal of Applied Physics},
    Year = {2006},
    Note = {Marcus, Matthew S. Simmons, J. M. Castellini, O. M. Hamers, R. J. Eriksson, M. A.},
    Number = {8},
    Volume = {100},
    Abstract = {Optoelectronic measurements of carbon nanotube transistors have shown a wide variety of sensitivites to the incident light. Direct photocurrent processes compete with a number of extrinsic mechanisms. Here we show that visible light absorption in the silicon substrate generates a photovoltage that can electrically gate the nanotube device. The photocurrent induced by the changing gate voltage can be significantly larger than that due to direct electron-hole pair generation in the nanotube. The dominance of photogating in these devices is confirmed by the power and position dependence of the resulting photocurrent. The power dependence is strongly nonlinear and photocurrents are measured through the device even when the laser illuminates up to 1 mm from the nanotube. (c) 2006 American Institute of Physics.},
    Doi = {084306
    10.1063/1.2357413},
    ISSN = {0021-8979},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000241721900074
    http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JAPIAU000100000008084306000001&idtype=cvips&doi=10.1063/1.2357413&prog=normal}
    }
  • [DOI] Kim, H., P. E. Colavita, K. M. Metz, B. M. Nichols, B. Sun, J. Uhlrich, X. Y. Wang, T. F. Kuech, and R. J. Hamers. Photochemical functionalization of gallium nitride thin films with molecular and biomolecular layers. Langmuir 2006, 22, 8121-8126.
    [Bibtex]
    @Article{Hamers93,
    Title = {Photochemical functionalization of gallium nitride thin films with molecular and biomolecular layers},
    Author = {Kim, H. and Colavita, P. E. and Metz, K. M. and Nichols, B. M. and Sun, B. and Uhlrich, J. and Wang, X. Y. and Kuech, T. F. and Hamers, R. J.},
    Journal = {Langmuir},
    Year = {2006},
    Note = {Kim, Heesuk Colavita, Paula E. Metz, Kevin M. Nichols, Beth M. Sun, Bin Uhlrich, John Wang, Xiaoyu Kuech, Thomas F. Hamers, Robert J.},
    Number = {19},
    Pages = {8121-8126},
    Volume = {22},
    Abstract = {We demonstrate that photochemical functionalization can be used to functionalize and photopattern the surface of gallium nitride crystalline thin films with well- defined molecular and biomolecular layers. GaN (0001) surfaces exposed to a hydrogen plasma will react with organic molecules bearing an alkene ( C=C) group when illuminated with 254 nm light. Using a bifunctional molecule with an alkene group at one end and a protected amine group at the other, this process can be used to link the alkene group to the surface, leaving the protected amine exposed. Using a simple contact mask, we demonstrate the ability to directly pattern the spatial distribution of these protected amine groups on the surface with a lateral resolution of < 12 mu m. After deprotection of the amines, single- stranded DNA oligonucleotides were linked to the surface using a bifunctional cross- linker. Measurements using fluorescently labeled complementary and noncomplementary sequences show that the DNA- modified GaN surfaces exhibit excellent selectivity, while repeated cycles of hybridization and denaturation in urea show good stability. These results demonstrate that photochemical functionalization can be used as an attractive starting point for interfacing molecular and biomolecular systems with GaN and other compound semiconductors.},
    Doi = {10.1021/la0610708},
    ISSN = {0743-7463},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000240250600029
    http://pubs.acs.org/doi/pdfplus/10.1021/la0610708}
    }
  • [DOI] Baker, S. E., P. E. Colavita, K. Y. Tse, and R. J. Hamers. Functionalized vertically aligned carbon nanofibers as scaffolds for immobilization and electrochemical detection of redox-active proteins. Chemistry of Materials 2006, 18, 4415-4422.
    [Bibtex]
    @Article{Hamers94,
    Title = {Functionalized vertically aligned carbon nanofibers as scaffolds for immobilization and electrochemical detection of redox-active proteins},
    Author = {Baker, S. E. and Colavita, P. E. and Tse, K. Y. and Hamers, R. J.},
    Journal = {Chemistry of Materials},
    Year = {2006},
    Note = {Baker, Sarah E. Colavita, Paula E. Tse, Kiu-Yuen Hamers, Robert J.},
    Number = {18},
    Pages = {4415-4422},
    Volume = {18},
    Abstract = {We have investigated the functionalization of vertically aligned carbon nanofibers with the redox-active protein cytochrome c and have characterized the resulting chemical and electrochemical activity. A comparison of monolayers with different terminal groups shows that those exposing carboxylic acid groups are most effective at binding active cytochrome c to carbon nanofibers. Cyclic voltammetry (CV) measurements reveal redox peaks due to electrochemical activity of the nanofiber-bound protein. CV and chemical measurements of enzymatic activity both show that nanofibers modified with cytochrome c yield approximately 10 times more activity than similarly modified surfaces of glassy carbon and gold. However, cytochrome c-modified nanofibers yield a high capacitive background, reducing the signal-to-noise ratio of the electrical measurements. We attribute this in part to inhomogeneous functionalization of the nanofibers at edge-plane versus basal-plane sites on the nanofiber surface, leading to leaky monolayers that yield increased capacitance. Our results demonstrate the ability to link chemically and electrochemically active proteins to nanofibers in a manner that preserves their activity and provide insight into the nanometer-scale factors that control the resulting chemical and electrochemical properties of biologically modified nanostructured electrodes.},
    Doi = {10.1021/cm0609000},
    ISSN = {0897-4756},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000240072000032
    http://pubs.acs.org/doi/pdfplus/10.1021/cm0609000}
    }
  • [DOI] Hamers, R. J.. Passivation and activation: How do monovalent atoms modify the reactivity of silicon surfaces? A perspective on the article, "The mechanism of amine formation on Si(100) activated with chlorine atoms", by C. C. Finstad, A.D. Thorsness, and A.J. Muscat. Surface Science 2006, 600, 3361-3362.
    [Bibtex]
    @Article{Hamers95,
    Title = {Passivation and activation: How do monovalent atoms modify the reactivity of silicon surfaces? A perspective on the article, "The mechanism of amine formation on Si(100) activated with chlorine atoms", by C. C. Finstad, A.D. Thorsness, and A.J. Muscat},
    Author = {Hamers, R. J.},
    Journal = {Surface Science},
    Year = {2006},
    Note = {Hamers, Robert J.},
    Number = {17},
    Pages = {3361-3362},
    Volume = {600},
    Doi = {10.1016/j.susc.2006.05.025},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000240893300001
    http://www.sciencedirect.com/science/article/pii/S0039602806006224}
    }
  • [DOI] Schwartz, M. P., D. E. Barlow, J. N. Russell, K. P. Weidkamp, J. E. Butler, M. P. D’Evelyn, and R. J. Hamers. Semiconductor surface-induced 1,3-hydrogen shift: The role of covalent vs zwitterionic character. Journal of the American Chemical Society 2006, 128, 11054-11061.
    [Bibtex]
    @Article{Hamers96,
    Title = {Semiconductor surface-induced 1,3-hydrogen shift: The role of covalent vs zwitterionic character},
    Author = {Schwartz, M. P. and Barlow, D. E. and Russell, J. N. and Weidkamp, K. P. and Butler, J. E. and D'Evelyn, M. P. and Hamers, R. J.},
    Journal = {Journal of the American Chemical Society},
    Year = {2006},
    Note = {Schwartz, Michael P. Barlow, Daniel E. Russell, John N., Jr. Weidkamp, Kevin P. Butler, James E. D'Evelyn, Mark P. Hamers, Robert J.},
    Number = {34},
    Pages = {11054-11061},
    Volume = {128},
    Abstract = {X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy ( FTIR) are used to compare the reaction of 1,2-cyclohexanedione (1,2-CHD) with Si(001) and diamond( 001) surface dimers under ultra-high-vacuum conditions. 1,2-CHD is known to undergo a keto-enol tautomerization, with the monoenol being the primary equilibrium species in the solid and gas phases. XPS and FTIR data demonstrate that 1,2-CHD reacts with diamond( 001) through the OH group of the monoenol, resulting in only one O atom being bonded to the surface. In contrast, XPS and FTIR data suggest that both oxygen atoms in the 1,2-CHD molecule bond via Si-O-C linkages to the Si(001) surface dimer, and that the molecule undergoes an intramolecular 1,3-H shift. While the Si(001) and diamond(001) surfaces are both comprised of surface dimers, the diamond(001) dimer is symmetric, with little charge separation, whereas the Si(001) dimer is tilted and exhibits zwitterionic character. The different reaction products that are observed when clean Si(001) and diamond(001) surfaces are exposed to 1,2-CHD demonstrate the importance of charge separation in promoting a 1,3-H shift and provide new mechanistic insights that may be applicable to a variety of organic reactions.},
    Doi = {10.1021/ja060598w},
    ISSN = {0002-7863},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000239932500032
    http://pubs.acs.org/doi/pdfplus/10.1021/ja060598w}
    }
  • [DOI] Nichols, B. M., K. M. Metz, K. Y. Tse, J. E. Butler, J. N. Russell, and R. J. Hamers. Electrical bias dependent photochemical functionalization of diamond surfaces. Journal of Physical Chemistry B 2006, 110, 16535-16543.
    [Bibtex]
    @Article{Hamers97,
    Title = {Electrical bias dependent photochemical functionalization of diamond surfaces},
    Author = {Nichols, B. M. and Metz, K. M. and Tse, K. Y. and Butler, J. E. and Russell, J. N. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {2006},
    Note = {Nichols, Beth M. Metz, Kevin M. Tse, Kiu-Yuen Butler, James E. Russell, John N., Jr. Hamers, Robert J.},
    Number = {33},
    Pages = {16535-16543},
    Volume = {110},
    Abstract = {Diamond is an excellent substrate for many sensing and electronic applications because of its outstanding stability in biological and aqueous environments. When the diamond surface is H-terminated, it can be covalently modified with organic alkenes using wet photochemical methods that are surface-mediated and initiated by the ejection of electrons from the diamond. To develop a better understanding of the photochemical reaction mechanism, we examine the effect of applying an electrical bias to the diamond samples during the photochemical reaction. Applying a 1 V potential between two diamond electrodes significantly increases the rate of functionalization of the negative electrode. Cyclic voltammetry and electrochemical impedance measurements show that the 1 V potential induces strong downward band-bending within the diamond film of the negative electrode. At higher voltages a Faradaic current is observed, with no further acceleration of the functionalization rate. We attribute the bias-dependent changes in rate to a field effect, in which the applied potential induces a strong downward band-bending on the negative electrode and facilitates the ejection of electrons into the adjacent fluid of reactant organic alkenes. We also demonstrate the ability to directly photopattern the surface with reactant molecules on length scales of < 25 Am, the smallest we have measured, using simple photomasking techniques.},
    Doi = {10.1021/jp062443g},
    ISSN = {1520-6106},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000239818000056
    http://pubs.acs.org/doi/pdfplus/10.1021/jp062443g}
    }
  • [DOI] Simmons, J. M., B. M. Nichols, M. S. Marcus, O. M. Castellini, R. J. Hamers, and M. A. Eriksson. Critical oxide thickness for efficient single-walled carbon nanotube growth on silicon using thin SiO2 diffusion barriers. Small 2006, 2, 902-909.
    [Bibtex]
    @Article{Hamers98,
    Title = {Critical oxide thickness for efficient single-walled carbon nanotube growth on silicon using thin SiO2 diffusion barriers},
    Author = {Simmons, J. M. and Nichols, B. M. and Marcus, M. S. and Castellini, O. M. and Hamers, R. J. and Eriksson, M. A.},
    Journal = {Small},
    Year = {2006},
    Note = {Simmons, JM Nichols, BM Marcus, MS Castellini, OM Hamers, RJ Eriksson, MA},
    Number = {7},
    Pages = {902-909},
    Volume = {2},
    Abstract = {The ability to integrate carbon nanotubes, especially single-walled carbon nanotubes, seamlessly onto silicon would expand their range of applications considerably. Though direct integration using chemical vapor deposition is the simplest method, the growth of single-walled carbon nanotubes on bare silicon and on ultrathin oxides is greatly inhibited due to the formation of a noncatalytic silicide. Using X-ray photoelectron spectroscopy, we show that silicide formation occurs on ultrathin oxides due to thermally activated metal diffusion through the oxide. Silicides affect the growth of single-walled nanotubes more than multi-walled nanotubes due to the increased kinetics at the higher single-walled nanotube growth temperature. We demonstrate that nickel and iron catalysts, when deposited on clean silicon or ultrathin silicon dioxide layers, begin to form silicides at relatively low temperatures, and that by 900 degrees C, all of the catalyst has been incorporated into the silicide, rendering it inactive for subsequent single-walled nanotube growth. We further show that a 4-nm silicon dioxide layer is the minimum diffusion barrier thickness that allows for efficient single-walled nanotube growth.},
    Doi = {10.1002/smll.200600095},
    ISSN = {1613-6810},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000238159300014
    http://onlinelibrary.wiley.com/store/10.1002/smll.200600095/asset/902_ftp.pdf?v=1&t=hak67ucw&s=e3379722470ff9ac54bf77a7b3cef021c745574a}
    }
  • [DOI] Hamers, R. J., J. D. Beck, M. A. Eriksson, B. Li, M. S. Marcus, L. Shang, J. Simmons, and J. A. Streifer. Electrically directed assembly and detection of nanowire bridges in aqueous media. Nanotechnology 2006, 17, S280-S286.
    [Bibtex]
    @Article{Hamers99,
    Title = {Electrically directed assembly and detection of nanowire bridges in aqueous media},
    Author = {Hamers, R. J. and Beck, J. D. and Eriksson, M. A. and Li, B. and Marcus, M. S. and Shang, L. and Simmons, J. and Streifer, J. A.},
    Journal = {Nanotechnology},
    Year = {2006},
    Note = {Hamers, RJ Beck, JD Eriksson, MA Li, B Marcus, MS Shang, L Simmons, J Streifer, JA},
    Number = {11},
    Pages = {S280-S286},
    Volume = {17},
    Abstract = {Although dielectrophoresis has been used previously to manipulate a variety of nanoscale materials, manipulation in ionic solutions is more difficult due to the high dielectric constant of water and the formation of electrical double-layers. Here, we report experiments aimed at the manipulation of nanowires in aqueous media and real-time detection of nanowire bridging events. Real-time video images demonstrate the ability to manipulate individual nanowires in aqueous media by capturing them along the edges of electrodes, and using a slow fluid flow to transport them until they bridge across micron-sized electrode gaps. By using special cancellation schemes, we demonstrate that it is possible to eliminate the effects of background currents through the electrolyte, and to electrically detect the bridging of electrodes by individual nanowires and nanowire bundles. These results have been obtained using gold nanowires with diameters ranging from similar to 50 to 250 nm, similar to 50 nm diameter silicon nanowires, and similar to 70 nm diameter carbon nanofibres.},
    Doi = {10.1088/0957-4484/17/11/s09},
    ISSN = {0957-4484},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000238250300010
    http://iopscience.iop.org/0957-4484/17/11/S09/pdf/0957-4484_17_11_S09.pdf}
    }

2005

  • [DOI] Shang, L., T. L. Clare, M. A. Eriksson, M. S. Marcus, K. M. Metz, and R. J. Hamers. Electrical characterization of nanowire bridges incorporating biomolecular recognition elements. Nanotechnology 2005, 16, 2846-2851.
    [Bibtex]
    @Article{Hamers105,
    Title = {Electrical characterization of nanowire bridges incorporating biomolecular recognition elements},
    Author = {Shang, L. and Clare, T. L. and Eriksson, M. A. and Marcus, M. S. and Metz, K. M. and Hamers, R. J.},
    Journal = {Nanotechnology},
    Year = {2005},
    Note = {Shang, L Clare, TL Eriksson, MA Marcus, MS Metz, KM Hamers, RJ},
    Number = {12},
    Pages = {2846-2851},
    Volume = {16},
    Abstract = {We have investigated the formation and electrical properties of nanowire bridges formed when nanowires modified with the biomolecule biotin span across a gap between gold microelectrodes functionalized with the complementary biomolecule, avidin. Dielectrophoretic manipulation with a 1 MHz AC voltage is used to manipulate biotin-modified nanowires into the inter-electrode gap. Biomolecular recognition between the biotin-modified nanowires and the avidin-modified gold microelectrodes then holds the nanowires securely in place. By simultaneously applying a second, lower-frequency AC voltage and using lock-in detection, we are able to monitor individual bridging events in real time and to characterize the change in electrical response associated with individual nanowire bridges. The combined use of physical manipulation with biomolecular recognition can be used for selective assembly of nanoscale materials, as well as analytical application as a biologically activated switch in which an electrical contact is controlled by a biomolecular recognition process.},
    Doi = {10.1088/0957-4484/16/12/019},
    ISSN = {0957-4484},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000234304000027
    http://iopscience.iop.org/0957-4484/16/12/019/pdf/0957-4484_16_12_019.pdf}
    }
  • [DOI] Nichols, B. M., J. E. Butler, J. N. Russell, and R. J. Hamers. Photochemical functionalization of hydrogen-terminated diamond surfaces: A structural and mechanistic study. Journal of Physical Chemistry B 2005, 109, 20938-20947.
    [Bibtex]
    @Article{Hamers106,
    Title = {Photochemical functionalization of hydrogen-terminated diamond surfaces: A structural and mechanistic study},
    Author = {Nichols, B. M. and Butler, J. E. and Russell, J. N. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {2005},
    Note = {Nichols, BM Butler, JE Russell, JN Hamers, RJ},
    Number = {44},
    Pages = {20938-20947},
    Volume = {109},
    Abstract = {Hydrogen-terminated diamond surfaces can be covalently modified with molecules bearing a terminal vinyl (C=C) group via a photochemical process using sub-band-gap light at 254 nm. We have investigated the photochemical modification of hydrogen-terminated surfaces of nanocrystalline and single-crystal diamond (111) to help understand the structure of the films and the underlying mechanism of photochemical furictionalization. A comparison of the rates of photochemical modification of single-crystal diamond and nanocrystalline diamond films shows no significant difference in reactivity, demonstrating that the modification process is not controlled by grain boundaries or other structures unique to polycrystalline, films. We find that both single-crystal and polycrystalline hydrogen-terminated diamond samples exhibit negative electron affinity and are functionalized at comparable rates, while oxidized surfaces with positive electron affinity undergo no detectable reaction. Gas chromatography-mass spectrometry (GC-MS) analysis shows the formation of new chemical products in the liquid phase that are formed only when the alkenes are illuminated in direct contact with H-terminated diamond, while control experiments with other surfaces and in the dark show no reaction. Our results show that the functionalization is a surface-mediated photochemical reaction and suggest that modification is initiated by the photoejection of electrons from the diamond surfaces into the liquid phase.},
    Doi = {10.1021/jp0545389},
    ISSN = {1520-6106},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000233342400041
    http://pubs.acs.org/doi/pdfplus/10.1021/jp0545389}
    }
  • [DOI] Baker, S. E., K. Y. Tse, E. Hindin, B. M. Nichols, T. L. Clare, and R. J. Hamers. Covalent functionalization for biomolecular recognition on vertically aligned carbon nanofibers. Chemistry of Materials 2005, 17, 4971-4978.
    [Bibtex]
    @Article{Hamers107,
    Title = {Covalent functionalization for biomolecular recognition on vertically aligned carbon nanofibers},
    Author = {Baker, S. E. and Tse, K. Y. and Hindin, E. and Nichols, B. M. and Clare, T. L. and Hamers, R. J.},
    Journal = {Chemistry of Materials},
    Year = {2005},
    Note = {Baker, SE Tse, KY Hindin, E Nichols, BM Clare, TL Hamers, RJ},
    Number = {20},
    Pages = {4971-4978},
    Volume = {17},
    Abstract = {We compare two different strategies for covalently modifying carbon nanofibers with biological molecules such as DNA. One method begins with a photochemical reaction between the nanofibers and molecules bearing both a terminal olefin group and a protected amine group followed by deprotection to yield the free primary amine. The second method uses a chemical reaction of an aryldiazonium salt with the nanofibers followed by electrochemical reduction to the primary amine. Both methods then link the primary amines to thio-terminated DNA oligonucleotides. Our measurements show that both methods yield DNA-modified carbon nanofibers exhibiting excellent specificity and reversibility in binding to DNA probe molecules in solution having complementary vs noncomplementary sequences. Quantitative measurements show that 2.3 x 10(14) DNA molecules/cm(2) will hybridize to the DNA-modified nanofiber samples, approximately eight times higher than for a flat sample of glassy carbon functionalized in an identical manner. Similar results were obtained comparing the amount of avidin that specifically binds to biotin-modified surfaces of nanofibers and glassy carbon. Our results demonstrate the ability to covalently functionalize nanofibers via two different methods that both provide excellent biomolecular recognition properties. Since the photochemical method uses molecules that are highly insulating while the diazonium method uses molecules bearing aromatic groups that are expected to be conductive, these methods can be used to prepare biologically modified nanofibers with a range of electrical properties that may be useful for electrical sensing of specific biomolecules in solution.},
    Doi = {10.1021/cm051024d},
    ISSN = {0897-4756},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000232326700011
    http://pubs.acs.org/doi/pdfplus/10.1021/cm051024d}
    }
  • [DOI] Streifer, J. A., H. Kim, B. M. Nichols, and R. J. Hamers. Covalent functionalization and biomolecular recognition properties of DNA-modified silicon nanowires. Nanotechnology 2005, 16, 1868-1873.
    [Bibtex]
    @Article{Hamers108,
    Title = {Covalent functionalization and biomolecular recognition properties of DNA-modified silicon nanowires},
    Author = {Streifer, J. A. and Kim, H. and Nichols, B. M. and Hamers, R. J.},
    Journal = {Nanotechnology},
    Year = {2005},
    Note = {Streifer, JA Kim, H Nichols, BM Hamers, RJ},
    Number = {9},
    Pages = {1868-1873},
    Volume = {16},
    Abstract = {The direct covalent modification of silicon nanowires with DNA oligonucleotides, and the subsequent hybridization properties of the resulting nanowire-DNA adducts, are described. X-ray photoelectron spectroscopy and fluorescence imaging techniques have been used to characterize the covalent photochemical functionalization of hydrogen-terminated silicon nanowires grown on SiO2 substrates and the subsequent chemistry to form covalent adducts with DNA. XPS measurements show that photochemical reaction of H-terminated Si nanowires with alkenes occurs selectively on the nanowires with no significant reaction with the underlying SiO2 substrate, and that the resulting molecular layers have a packing density identical to that of planar samples. Functionalization with a protected amine followed by deprotection and use of a bifunctional linker yields covalently linked nanowire-DNA adducts. The biomolecular recognition properties of the nanowires were tested via hybridization with fluorescently tagged complementary and non-complementary DNA oligonucleotides, showing good selectivity and reversibility, with no significant non-specific binding to the incorrect sequences or to the underlying SiO2 substrate. Our results demonstrate that the selective nature of the photochemical functionalization chemistry permits silicon nanowires to be grown, functionalized, and characterized before being released from the underlying SiO2 substrate. Compared with solution-phase modification, the ability to perform all chemistry and characterization while still attached to the underlying support makes this a convenient route toward fabrication of well characterized, biologically modified silicon nanowires.},
    Doi = {10.1088/0957-4484/16/9/075},
    ISSN = {0957-4484},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000232089500075
    http://iopscience.iop.org/0957-4484/16/9/075/pdf/0957-4484_16_9_075.pdf}
    }
  • [DOI] Clare, T. L., B. H. Clare, B. M. Nichols, N. L. Abbott, and R. J. Hamers. Functional monolayers for improved resistance to protein adsorption: Oligo(ethylene glycol)-modified silicon and diamond surfaces. Langmuir 2005, 21, 6344-6355.
    [Bibtex]
    @Article{Hamers110,
    Title = {Functional monolayers for improved resistance to protein adsorption: Oligo(ethylene glycol)-modified silicon and diamond surfaces},
    Author = {Clare, T. L. and Clare, B. H. and Nichols, B. M. and Abbott, N. L. and Hamers, R. J.},
    Journal = {Langmuir},
    Year = {2005},
    Note = {Clare, TL Clare, BH Nichols, BM Abbott, NL Hamers, RJ},
    Number = {14},
    Pages = {6344-6355},
    Volume = {21},
    Abstract = {The interaction of proteins with semiconductors such as silicon and diamond is of great interest for applications such as electronic biosensing. We have investigated the use of covalently bound oligo(ethylene glycol), EG, monolayers on diamond and silicon to minimize nonspecific protein adsorption. Protein adsorption was monitored by fluorescence scanning as a function of the length of the ethylene glycol chain (EG3 through EG6) and the terminal functional group (methyl- versus hydroxyl-terminated EG3 monolayer). More quantitative measurements were made by eluting adsorbed avidin from the surface and measuring the intensity of fluorescence in the solution. The attachment chemistry of the tri(ethylene glycol) molecules and monolayer orientation was studied by X-ray photoelectron spectroscopy. Improvement in the selectivity of surfaces modified with EG functionality was demonstrated in two model biosensing assays. We find that high-quality EG monolayers are formed on silicon and diamond and that these EG3 monolayers are as effective as EG3 self-assembled monolayers on gold at resisting nonspecific avidin adsorption. These results show promise for use of silicon and diamond materials in many potential applications such as biosensing and medical implants.},
    Doi = {10.1021/la050362q},
    ISSN = {0743-7463},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000230248500035
    http://pubs.acs.org/doi/pdfplus/10.1021/la050362q}
    }
  • [DOI] Schwartz, M. P., D. E. Barlow, J. N. Russell, J. E. Butler, M. P. D’Evelyn, and R. J. Hamers. Adsorption of acrylonitrile on diamond and silicon (001)-(2 x 1) surfaces: Effects of dimer structure on reaction pathways and product distributions. Journal of the American Chemical Society 2005, 127, 8348-8354.
    [Bibtex]
    @Article{Hamers111,
    Title = {Adsorption of acrylonitrile on diamond and silicon (001)-(2 x 1) surfaces: Effects of dimer structure on reaction pathways and product distributions},
    Author = {Schwartz, M. P. and Barlow, D. E. and Russell, J. N. and Butler, J. E. and D'Evelyn, M. P. and Hamers, R. J.},
    Journal = {Journal of the American Chemical Society},
    Year = {2005},
    Note = {Schwartz, MP Barlow, DE Russell, JN Butler, JE D'Evelyn, MP Hamers, RJ},
    Number = {23},
    Pages = {8348-8354},
    Volume = {127},
    Abstract = {Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) are used to compare the reaction of acrylonitrile with Si(001) and C(001) (diamond) surfaces. Our results show that reaction with Si(001) and C(001) yield very different product distributions that result from fundamental differences in the ionic character of these surfaces. While acrylonitrile reacts with the C(001) surface via a [2 + 2] cycloaddition reaction in a manner similar to nonpolar molecules such as alkenes and disilenes, reaction with the Si(001) surface occurs largely through the nitrile group. This work represents the first experimental example of how differences in dimer structure lead to very different chemistry for C(001) compared to that for Si(001). The fact that Si(001) reacts with the strongly polar nitrile group of acrylonitrile indicates that the zwitterionic character of this surface controls its reactivity. C(001) dimers, on the other hand, behave more like a true molecular double bond, albeit a highly strained one. Consequently, while alternative strategies will be necessary for chemical modification of Si(001), traditional schemes from organic chemistry for functionalization of alkenes and disilenes may be available for building molecular layers on C(001).},
    Doi = {10.1021/ja042701s},
    ISSN = {0002-7863},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000229751100042
    http://pubs.acs.org/doi/pdfplus/10.1021/ja042701s}
    }
  • [DOI] Hamers, R. J.. Bond breaking at surfaces: Electrons or phonons?. Surface Science 2005, 583, 1-3.
    [Bibtex]
    @Article{Hamers112,
    Title = {Bond breaking at surfaces: Electrons or phonons?},
    Author = {Hamers, R. J.},
    Journal = {Surface Science},
    Year = {2005},
    Note = {Hamers, RJ},
    Number = {1},
    Pages = {1-3},
    Volume = {583},
    Doi = {10.1016/j.susc.2005.03.063},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000229423500001
    http://www.sciencedirect.com/science/article/pii/S0039602805003845}
    }
  • [DOI] Tse, K. Y., B. M. Nichols, W. S. Yang, J. E. Butler, J. N. Russell, and R. J. Hamers. Electrical properties of diamond surfaces functionalized with molecular monolayers. Journal of Physical Chemistry B 2005, 109, 8523-8532.
    [Bibtex]
    @Article{Hamers113,
    Title = {Electrical properties of diamond surfaces functionalized with molecular monolayers},
    Author = {Tse, K. Y. and Nichols, B. M. and Yang, W. S. and Butler, J. E. and Russell, J. N. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {2005},
    Note = {Tse, KY Nichols, BM Yang, WS Butler, JE Russell, JN Hamers, RJ},
    Number = {17},
    Pages = {8523-8532},
    Volume = {109},
    Abstract = {Recent studies have shown that semiconductor surfaces such as silicon and diamond can be functionalized with organic monolayers, and that these monolayer films can be used to tether biomolecules such as DNA to the surfaces. Electrical measurements of these interfaces show a change in response to DNA hybridization and other biological binding processes, but the fundamental nature of the electrical signal transduction has remained unclear. We have explored the electrical impedance of polycrystalline and single-crystal diamond surfaces modified with an organic monolayer produced by photochemical reaction of diamond with 1-dodecene. Our results show that, by measuring the impedance as a function of frequency and potential, it is possible to dissect the complex interfacial structure into frequency ranges where the total impedance is controlled by the molecular monolayer, by the diamond space-charge region, and by the electrolyte. The results have implications for understanding the ability to use molecularly modified semiconductor surfaces for applications such as chemical and biological sensing.},
    Doi = {10.1021/jp046433w},
    ISSN = {1520-6106},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000228847500034
    http://pubs.acs.org/doi/pdfplus/10.1021/jp046433w}
    }
  • [DOI] Beck, J. D., L. Shang, M. S. Marcus, and R. J. Hamers. Manipulation and real-time electrical detection of individual bacterial cells at electrode junctions: A model for assembly of nanoscale biosystems. Nano Letters 2005, 5, 777-781.
    [Bibtex]
    @Article{Hamers114,
    Title = {Manipulation and real-time electrical detection of individual bacterial cells at electrode junctions: A model for assembly of nanoscale biosystems},
    Author = {Beck, J. D. and Shang, L. and Marcus, M. S. and Hamers, R. J.},
    Journal = {Nano Letters},
    Year = {2005},
    Note = {Beck, JD Shang, L Marcus, MS Hamers, RJ},
    Number = {4},
    Pages = {777-781},
    Volume = {5},
    Abstract = {Biological cells are complex objects that have the potential to act as templates for the subsequent construction of nanoscale structures. We demonstrate the ability to controllably and reversibly manipulate individual, live bacterial cells across micron-sized electrical gaps, and to detect bridging directly through changes in the electrical response. Our model system, Bacillus mycoides, is a rod-shaped bacterium approximately 800 nm wide and 5 mu m long, similar in size and shape to many inorganic nanowires.},
    Doi = {10.1021/nl047861g},
    ISSN = {1530-6984},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000228468800041
    http://pubs.acs.org/doi/pdfplus/10.1021/nl047861g}
    }
  • [DOI] Yang, W. S., S. E. Baker, J. E. Butler, C. S. Lee, J. N. Russell, L. Shang, B. Sun, and R. J. Hamers. Electrically addressable biomolecular functionalization of conductive nanocrystalline diamond thin films. Chemistry of Materials 2005, 17, 938-940.
    [Bibtex]
    @Article{Hamers120,
    Title = {Electrically addressable biomolecular functionalization of conductive nanocrystalline diamond thin films},
    Author = {Yang, W. S. and Baker, S. E. and Butler, J. E. and Lee, C. S. and Russell, J. N. and Shang, L. and Sun, B. and Hamers, R. J.},
    Journal = {Chemistry of Materials},
    Year = {2005},
    Note = {Yang, WS Baker, SE Butler, JE Lee, CS Russell, JN Shang, L Sun, B Hamers, RJ},
    Number = {5},
    Pages = {938-940},
    Volume = {17},
    Doi = {10.1021/cm048060h},
    ISSN = {0897-4756},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000227421300004
    http://pubs.acs.org/doi/pdfplus/10.1021/cm048060h}
    }
  • [DOI] Hamers, R. J., J. E. Butler, T. Lasseter, B. M. Nichols, J. N. Russell, K. Y. Tse, and W. S. Yang. Molecular and biomolecular monolayers on diamond as an interface to biology. Diamond and Related Materials 2005, 14, 661-668.
    [Bibtex]
    @Article{Hamers121,
    Title = {Molecular and biomolecular monolayers on diamond as an interface to biology},
    Author = {Hamers, R. J. and Butler, J. E. and Lasseter, T. and Nichols, B. M. and Russell, J. N. and Tse, K. Y. and Yang, W. S.},
    Journal = {Diamond and Related Materials},
    Year = {2005},
    Note = {Hamers, RJ Butler, JE Lasseter, T Nichols, BM Russell, JN Tse, KY Yang, WS
    15th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides, and Silicon Carbide
    Sep 12-17, 2004
    Riva del Garda, ITALY
    Aixtron AG, Diamond Business-Magazine, Elsevier Ltd, Iplas Innovat Plasma Syst GmbH, Roth \& Rau AG, Seki Technotron Corp
    Si},
    Number = {3-7},
    Pages = {661-668},
    Volume = {14},
    Abstract = {Covalent modification of diamond surfaces with molecular monolayers serves as a starting point for linking biomolecules such as DNA and proteins to surfaces. DNA-modified diamond surfaces show excellent selectivity for hybridization with complementary vs. noncomplementary sequences and outstanding stability. These biomolecular recognition events also lead to changes in the conductivity of the interface via a molecular field effect in which the negative charge oil the DNA molecules alters the conductivity ill the diamond thin film. Chemical modification of the diamond with ethylene glycol oligomers leads to surfaces that effectively resist the nonspecific adsorption of proteins and other biomolecules to the surface. These outstanding physical and chemical properties of chemically modified diamond surfaces present new opportunities for the use of diamond thin films in biological applications. (c) 2004 Elsevier B.V. All rights reserved.},
    Doi = {10.1016/j.diamond.2004.09.018},
    ISSN = {0925-9635},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000229751400081
    http://www.sciencedirect.com/science/article/pii/S0925963504003383}
    }
  • [DOI] Hamers, R. J.. 2005. Interfacing Biological Molecules with Group IV Semiconductors for Bioelectronic Sensing. Bioelectronics: From Theory to Applications. .
    [Bibtex]
    @Book{Hamers122,
    title = {Interfacing Biological Molecules with Group IV Semiconductors for Bioelectronic Sensing},
    year = {2005},
    author = {Hamers, R. J.},
    series = {Bioelectronics: From Theory to Applications},
    note = {Hamers, Robert J.},
    doi = {10.1002/352760376X.ch7},
    isbn = {978-3-52760-376-3},
    pages = {209--230},
    type = {Book},
    }
  • Hamers, R. J.. 2005. Scanning tunneling microscopy. Edited by Lerner, R. G. and G. L. Triggs. In Encyclopedia of Physics, VCH-Wiley. .
    [Bibtex]
    @InBook{Hamers521,
    Title = {Scanning tunneling microscopy},
    Author = {Hamers, R. J.},
    Editor = {Lerner, R. G. and Triggs, G. L.},
    Publisher = {VCH-Wiley},
    Year = {2005},
    Type = {Book Section},
    Booktitle = {Encyclopedia of Physics}
    }
  • Hamers, R. J.. 2005. Diamond Thin Films. Edited by Lerner, R. G. and G. L. Triggs. In McGraw-Hill Encyclopedia of Science and Technology, 10th edition, .
    [Bibtex]
    @InBook{Hamers536,
    Title = {Diamond Thin Films},
    Author = {Hamers, R. J.},
    Editor = {Lerner, R. G. and Triggs, G. L.},
    Year = {2005},
    Type = {Book Section},
    Booktitle = {McGraw-Hill Encyclopedia of Science and Technology, 10th edition }
    }

2004

  • [DOI] Yang, W. S. and R. J. Hamers. Fabrication and characterization of a biologically sensitive field-effect transistor using a nanocrystalline diamond thin film. Applied Physics Letters 2004, 85, 3626-3628.
    [Bibtex]
    @Article{Hamers123,
    Title = {Fabrication and characterization of a biologically sensitive field-effect transistor using a nanocrystalline diamond thin film},
    Author = {Yang, W. S. and Hamers, R. J.},
    Journal = {Applied Physics Letters},
    Year = {2004},
    Note = {Yang, WS Hamers, RJ},
    Number = {16},
    Pages = {3626-3628},
    Volume = {85},
    Abstract = {We report the fabrication and characterization of a biologically sensitive field-effect transistor (Bio-FET) using a nanocrystalline diamond thin film. Biomolecular recognition capability was provided by linking human immunoglobulin G (IgG) to the diamond surface. Electrical measurements reveal behavior characteristic of field-effect transistors. The biomolecular recognition and specificity characteristics were tested using the two antibodies anti IgM and anti-IgG. Electrical measurements show that the Bio-FET device made on an IgG-modified diamond exhibits a response specific to the anti-IgG antibody. Our results demonstrate the ability to fabricate a bio-FET device using a biologically modified diamond thin film. (C) 2004 American Institute of Physics.},
    Doi = {10.1063/1.1808885},
    ISSN = {0003-6951},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000224658100096
    http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=APPLAB000085000016003626000001&idtype=cvips&doi=10.1063/1.1808885&prog=normal}
    }
  • [DOI] Weidkamp, K. P., A. Afzali, R. M. Tromp, and R. J. Hamers. A photopatternable pentacene precursor for use in organic thin-film transistors. Journal of the American Chemical Society 2004, 126, 12740-12741.
    [Bibtex]
    @Article{Hamers124,
    Title = {A photopatternable pentacene precursor for use in organic thin-film transistors},
    Author = {Weidkamp, K. P. and Afzali, A. and Tromp, R. M. and Hamers, R. J.},
    Journal = {Journal of the American Chemical Society},
    Year = {2004},
    Note = {Weidkamp, KP Afzali, A Tromp, RM Hamers, RJ},
    Number = {40},
    Pages = {12740-12741},
    Volume = {126},
    Doi = {10.1021/ja045228r},
    ISSN = {0002-7863},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000224357700015
    http://pubs.acs.org/doi/pdfplus/10.1021/ja045228r}
    }
  • [DOI] Lee, C. S., S. E. Baker, M. S. Marcus, W. S. Yang, M. A. Eriksson, and R. J. Hamers. Electrically addressable biomolecular functionalization of carbon nanotube and carbon nanofiber electrodes. Nano Letters 2004, 4, 1713-1716.
    [Bibtex]
    @Article{Hamers125,
    Title = {Electrically addressable biomolecular functionalization of carbon nanotube and carbon nanofiber electrodes},
    Author = {Lee, C. S. and Baker, S. E. and Marcus, M. S. and Yang, W. S. and Eriksson, M. A. and Hamers, R. J.},
    Journal = {Nano Letters},
    Year = {2004},
    Note = {Lee, CS Baker, SE Marcus, MS Yang, WS Eriksson, MA Hamers, RJ},
    Number = {9},
    Pages = {1713-1716},
    Volume = {4},
    Abstract = {We demonstrate the electrically addressable biomolecular functionalization of single-walled carbon nanotube electrodes and vertically aligned carbon nanofiber electrodes. The method uses an electrochemical reaction in which nitro groups on specific nanostructures are reduced to amino groups and then used to covalently link DNA to only these nanostructures. We demonstrate fabrication of a four-element array of distinct DNA oligonucleotides on carbon nanotube electrodes and the addressable functionalization of submicron bundles of <100 nm diameter vertically aligned carbon nanofibers. DNA hybridization shows that the DNA-modified nanoscale structures have excellent biological selectivity.},
    Doi = {10.1021/nl048995x},
    ISSN = {1530-6984},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000223837200027
    http://pubs.acs.org/doi/pdfplus/10.1021/nl048995x}
    }
  • [DOI] Lasseter, T. L., B. H. Clare, N. L. Abbott, and R. J. Hamers. Covalently modified silicon and diamond surfaces: Resistance to nonspecific protein adsorption and optimization for biosensing. Journal of the American Chemical Society 2004, 126, 10220-10221.
    [Bibtex]
    @Article{Hamers126,
    Title = {Covalently modified silicon and diamond surfaces: Resistance to nonspecific protein adsorption and optimization for biosensing},
    Author = {Lasseter, T. L. and Clare, B. H. and Abbott, N. L. and Hamers, R. J.},
    Journal = {Journal of the American Chemical Society},
    Year = {2004},
    Note = {Lasseter, TL Clare, BH Abbott, NL Hamers, RJ},
    Number = {33},
    Pages = {10220-10221},
    Volume = {126},
    Doi = {10.1021/ja047642x},
    ISSN = {0002-7863},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000223433700014
    http://pubs.acs.org/doi/pdfplus/10.1021/ja047642x}
    }
  • [DOI] Yang, W. S., J. E. Butler, J. N. Russell, and R. J. Hamers. Interfacial electrical properties of DNA-modified diamond thin films: Intrinsic response and hybridization-induced field effects. Langmuir 2004, 20, 6778-6787.
    [Bibtex]
    @Article{Hamers128,
    Title = {Interfacial electrical properties of DNA-modified diamond thin films: Intrinsic response and hybridization-induced field effects},
    Author = {Yang, W. S. and Butler, J. E. and Russell, J. N. and Hamers, R. J.},
    Journal = {Langmuir},
    Year = {2004},
    Note = {Yang, WS Butler, JE Russell, JN Hamers, RJ},
    Number = {16},
    Pages = {6778-6787},
    Volume = {20},
    Abstract = {We have investigated the frequency-dependent interfacial electrical properties of nanocrystalline diamond films that were covalently linked to DNA oligonucleotides and how these properties are changed upon exposure to complementary and noncomplementary DNA oligonucleotides. Frequency-dependent electrical measurements at the open-circuit potential show significant changes in impedance at frequencies of > 10(4) Hz when DNA-modified diamond films are exposed to complementary DNA, with only minimal changes when exposed to noncomplementary DNA molecules. Measurements as a function of potential show that at 10(5) Hz, the impedance is dominated by the space-charge region of the diamond film. DNA molecules hybridizing at the interface induce a field effect in the diamond space-charge layer, altering the impedance of the diamond film. By identifying a range of impedances where the impedance is dominated by the diamond space-charge layer, we show that it possible to directly observe DNA hybridization, in real time and without additional labels, via simple measurement of the interfacial impedance.},
    Doi = {10.1021/la036460y},
    ISSN = {0743-7463},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000223066700040
    http://pubs.acs.org/doi/pdfplus/10.1021/la036460y}
    }
  • [DOI] Cai, W., J. R. Peck, D. W. van der Weide, and R. J. Hamers. Direct electrical detection of hybridization at DNA-modified silicon surfaces. Biosensors & Bioelectronics 2004, 19, 1013-1019.
    [Bibtex]
    @Article{Hamers129,
    Title = {Direct electrical detection of hybridization at DNA-modified silicon surfaces},
    Author = {Cai, W. and Peck, J. R. and van der Weide, D. W. and Hamers, R. J.},
    Journal = {Biosensors \& Bioelectronics},
    Year = {2004},
    Note = {Cai, W Peck, JR van der Weide, DW Hamers, RJ},
    Number = {9},
    Pages = {1013-1019},
    Volume = {19},
    Abstract = {Electrochemical impedance spectroscopy was used to investigate the changes in interfacial electrical properties that arise when DNA-modified Si(1 1 1) surfaces are exposed to soution-phase DNA oligonucleotides with complementary and non-complementary sequences. The n- and p-type silicon(1 1 1) samples were covalently linked to DNA molecules via direct Si-C linkages without any intervening oxide layer. Exposure to solutions containing DNA oligonucleotides with the complementary sequence produced significant changes in both real and imaginary components of the electrical impedance, while exposure to DNA with non-complementary sequences generated negligible responses. These changes in electrical properties were corroborated with fluorescence measurements and were reproduced in multiple hybridization-denaturation cycles. The ability to detect DNA hybridization is strongly frequency-dependent. Modeling of the response and comparison of results on different silicon bulk doping shows that the sensitivity to DNA hybridization arises from DNA-induced changes in the resistance of the silicon substrate and the resistance of the molecular layers. (C) 2003 Elsevier B.V. All rights reserved.},
    Doi = {10.1016/j.bios.2003.09.009},
    ISSN = {0956-5663},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000220276100008
    http://www.sciencedirect.com/science/article/pii/S0956566303003373}
    }
  • [DOI] Lu, M. C., T. Knickerbocker, W. Cai, W. S. Yang, R. J. Hamers, and L. M. Smith. Invasive cleavage reactions on DNA-modified diamond surfaces. Biopolymers 2004, 73, 606-613.
    [Bibtex]
    @Article{Hamers130,
    Title = {Invasive cleavage reactions on DNA-modified diamond surfaces},
    Author = {Lu, M. C. and Knickerbocker, T. and Cai, W. and Yang, W. S. and Hamers, R. J. and Smith, L. M.},
    Journal = {Biopolymers},
    Year = {2004},
    Note = {Lu, MC Knickerbocker, T Cai, W Yang, WS Hamers, RJ Smith, LM},
    Number = {5},
    Pages = {606-613},
    Volume = {73},
    Abstract = {Recently developed DNA-modified diamond surfaces exhibit excellent chemical stability to high-temperature incubations ill biological buffers. The stability of these surfaces is substantially greater than that of gold or silicon surfaces, using similar surface attachment chemistry. The DNA molecules attached to the diamond surfaces are accessible to enzymes and call be modified ill surface enzymatic reactions. An important application a these surfaces is for surface invasive cleavage reactions, ill which target DNA strands added to the solution may result ill specific cleavage of surface-bound probe oligonucleotides, permitting analysis of single nucleotide polymorphisms (SNPs). Our previous work demonstrated the feasibility, of performing such cleavage reactions oil planar gold surfaces using PCR-amplified human genomic DNA as target. The sensitivity, of detection ill this earlier work was substantially limited by a lack of stability of the gold surface employed. In the present work, detection sensitivity is improved by a factor of similar to100 (100 amole of DNA target compared with 10 fmole ill the earlier work) by replacing the DNA-modified gold surface with a more stable DNA-modified diamond surface. (C) 2004 Wiley Periodicals, Inc.},
    Doi = {10.1002/bip.20007},
    ISSN = {0006-3525},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000220798700008
    http://onlinelibrary.wiley.com/store/10.1002/bip.20007/asset/20007_ftp.pdf?v=1&t=hak66pch&s=a445e0d21e51a6cc8223bb50829c74afcb7db327}
    }
  • [DOI] Lasseter, T. L., W. Cai, and R. J. Hamers. Frequency-dependent electrical detection of protein binding events. Analyst 2004, 129, 3-8.
    [Bibtex]
    @Article{Hamers134,
    Title = {Frequency-dependent electrical detection of protein binding events},
    Author = {Lasseter, T. L. and Cai, W. and Hamers, R. J.},
    Journal = {Analyst},
    Year = {2004},
    Note = {Lasseter, TL Cai, W Hamers, RJ},
    Number = {1},
    Pages = {3-8},
    Volume = {129},
    Abstract = {Frequency-dependent electrochemical impedance spectroscopy has been used to characterize the changes in electrical response that accompany specific binding of a protein to its substrate, using the biotin - avidin system as a model. Our results show that avidin, at concentrations in the nanomolar range, can be detected electrically in a completely label-free manner under conditions of zero average current flow and without the use of any auxiliary redox agents. Impedance measurements performed on biotin-modified surfaces of gold, glassy carbon, and silicon were obtained over a wide frequency range, from 5 mHz to 1 MHz. On each biotin-modified surface, binding of avidin is most easily detected at low frequencies, < 1 Hz. Electrical circuit modeling of the interface was used to relate the frequency-dependent electrical response to the physical structure of the interface before and after avidin binding. Electrical measurements were correlated with measurements of protein binding using fluorescently labeled avidin.},
    Doi = {10.1039/b307591e},
    ISSN = {0003-2654},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000187784900002
    http://pubs.rsc.org/en/content/articlepdf/2004/an/b307591e}
    }
  • Hamers, R. J.. 2004. Integrating biological molecules with Group IV semiconductors for bioelectronic sensing. Edited by Katz, E. and I. Willner. In Bioelectronics: Theory and application, VCH Publishers. .
    [Bibtex]
    @InBook{Hamers520,
    Title = {Integrating biological molecules with Group IV semiconductors for bioelectronic sensing},
    Author = {Hamers, R. J.},
    Editor = {Katz, E. and Willner, I.},
    Publisher = {VCH Publishers},
    Year = {2004},
    Type = {Book Section},
    Booktitle = {Bioelectronics: Theory and application}
    }

2003

  • [DOI] Druschel, G. K., R. J. Hamers, and J. F. Banfield. Kinetics and mechanism of polythionate oxidation to sulfate at low pH by O-2 and Fe3+. Geochimica Et Cosmochimica Acta 2003, 67, 4457-4469.
    [Bibtex]
    @Article{Hamers135,
    Title = {Kinetics and mechanism of polythionate oxidation to sulfate at low pH by O-2 and Fe3+},
    Author = {Druschel, G. K. and Hamers, R. J. and Banfield, J. F.},
    Journal = {Geochimica Et Cosmochimica Acta},
    Year = {2003},
    Note = {Druschel, GK Hamers, RJ Banfield, JF},
    Number = {23},
    Pages = {4457-4469},
    Volume = {67},
    Abstract = {Polythionates (SxO62-) are important in redox transformations involving many sulfur compounds. Here we investigate the oxidation kinetics and mechanisms of trithionate and tetrathionate oxidation between pH 0.4 and pH 2 in the presence of Fe3+ and/or oxygen. In these solutions, Fe3+ plus oxygen oxidizes tetrathionate and trithionate at least an order of magnitude faster than oxygen alone. Kinetic measurements, coupled with density functional calculations, suggest that the rate-limiting step for tetrathionate oxidation involves Fe3+ attachment, followed by electron density shifts that result in formation of a sulfite radical and S3O30 derivatives. The overall reaction orders for trithionate and tetrathionate are fractional due to rearrangement reactions and side reactions between reactants and intermediate products. The pseudo-first order rate coefficients for tetrathionate range from 10(-11) s(-1) at 25degreesC to 10(-8) s(-1) at 70degreesC, compared to 2 x 10(-7) s(-1) at 35 degreesC for trithionate. The apparent activation energy (E-A) for tetrathionate oxidation at pH 1.5 is 104.5 +/- 4.13 kJ/mol. A rate law at pH 1.5 and 70degreesC between 0.5 and 5 millimolar [Fe3+] is of the form: r = 10(-6.61+/-0.3)[S4O62-](0.3+/-0.08)[Fe3+](0.15+/-0.09) where rate, r, is in units of mol L-1 s(-1). In pH <1 solutions where trithionate forms by rearrangement of tetrathionate, trithionate oxidation is the rapid pathway for conversion of tetrathionate to sulfate. The kinetics of both trithionate and tetrathionate oxidation are several orders of magnitude slower than the formation of polythionates from thiosulfate in acidic, Fe3+-rich solutions. Copyright (C) 2003 Elsevier Ltd.},
    Doi = {10.1016/s0016-7037(03)00388-0},
    ISSN = {0016-7037},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000186772000001
    http://www.sciencedirect.com/science/article/pii/S0016703703003880}
    }
  • [DOI] Weidkamp, K. P., C. A. Hacker, M. P. Schwartz, X. P. Cao, R. M. Tromp, and R. J. Hamers. Interfacial chemistry of pentacene on clean and chemically modified silicon (001) surfaces. Journal of Physical Chemistry B 2003, 107, 11142-11148.
    [Bibtex]
    @Article{Hamers136,
    Title = {Interfacial chemistry of pentacene on clean and chemically modified silicon (001) surfaces},
    Author = {Weidkamp, K. P. and Hacker, C. A. and Schwartz, M. P. and Cao, X. P. and Tromp, R. M. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {2003},
    Note = {Weidkamp, KP Hacker, CA Schwartz, MP Cao, XP Tromp, RM Hamers, RJ},
    Number = {40},
    Pages = {11142-11148},
    Volume = {107},
    Abstract = {The interactions between pentacene and the Si(001)-(2 x 1) surface have been investigated using Fourier transform infrared spectroscopy (FTIR), ultraviolet photoelectron spectroscopy (UPS), and X-ray photoelectron spectroscopy (XPS). The pentacene molecules in the first layer react with the Si surface atoms through the C=C double bonds and via cleavage of C-H bonds. This chemisorption is accompanied by disruption of the conjugated pi electron system. The disrupted interfacial layer is stable throughout deposition and evaporation of thicker pentacene films. Pentacene molecules in layers beyond the first layer adsorb molecularly and yield well-defined valence band features that are characteristic of a conjugated pi electron system. Functionalization of the Si surface with a monolayer of cyclopentene inhibits dissociation of subsequently deposited pentacene molecules.},
    Doi = {10.1021/jp035385x},
    ISSN = {1520-6106},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000185756900024
    http://pubs.acs.org/doi/pdfplus/10.1021/jp035385x}
    }
  • [DOI] Hacker, C. A. and R. J. Hamers. Optical and electronic anisotropy of a pi-conjugated molecular monolayer on the silicon(001) surface. Journal of Physical Chemistry B 2003, 107, 7689-7695.
    [Bibtex]
    @Article{Hamers137,
    Title = {Optical and electronic anisotropy of a pi-conjugated molecular monolayer on the silicon(001) surface},
    Author = {Hacker, C. A. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {2003},
    Note = {Hacker, CA Hamers, RJ},
    Number = {31},
    Pages = {7689-7695},
    Volume = {107},
    Abstract = {The electronic and optical properties of an oriented monolayer of a 7-conjugated molecule, 9,10-phenanthrenequinone on a silicon(001) substrate were investigated. The adsorption of 9,10-phenanthrenequinone onto a single-domain, 4degrees-miscut Si(001) surface leads to an oriented monolayer film with intact,7, conjugation. Reflectance-difference spectroscopy (RDS) was used to probe the optical properties of the layer of 9,10-phenanthrenequinone, and comparison spectra were obtained on a monolayer 1,2-cyclohexanedione, a nonconjugated molecule that has a nearly identical structure at the Si-O-C interface. RDS spectra of the 9,10-phenanthrenequinone monolayer show a strong absorption feature at 5.2 eV due to pi-pi* transitions within the molecule, while spectra of the nonconjugated analogue show no feature in this region. Further information about the electronic structure is provided by ultraviolet photoemission spectroscopy of the chemisorbed monolayers and by ultraviolet-visible absorption spectroscopy of the parent compounds. The experiments confirm that it is possible to create a macroscopic optical anisotropy in organic films on silicon surfaces using the Si(001) dimers to control the molecular orientation.},
    Doi = {10.1021/jp021303d},
    ISSN = {1520-6106},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000184551300026
    http://pubs.acs.org/doi/pdfplus/10.1021/jp021303d}
    }
  • [DOI] Ardavan, A., M. Austwick, S. C. Benjamin, G. A. D. Briggs, T. J. S. Dennis, A. Ferguson, D. G. Hasko, M. Kanai, A. N. Khlobystov, B. W. Lovett, G. W. Morley, R. A. Oliver, D. G. Pettifor, K. Porfyrakis, J. H. Reina, J. H. Rice, J. D. Smith, R. A. Taylor, D. A. Williams, C. Adelmann, H. Mariette, and R. J. Hamers. Nanoscale solid-state quantum computing. Philosophical Transactions of the Royal Society a-Mathematical Physical and Engineering Sciences 2003, 361, 1473-1485.
    [Bibtex]
    @Article{Hamers138,
    Title = {Nanoscale solid-state quantum computing},
    Author = {Ardavan, A. and Austwick, M. and Benjamin, S. C. and Briggs, G. A. D. and Dennis, T. J. S. and Ferguson, A. and Hasko, D. G. and Kanai, M. and Khlobystov, A. N. and Lovett, B. W. and Morley, G. W. and Oliver, R. A. and Pettifor, D. G. and Porfyrakis, K. and Reina, J. H. and Rice, J. H. and Smith, J. D. and Taylor, R. A. and Williams, D. A. and Adelmann, C. and Mariette, H. and Hamers, R. J.},
    Journal = {Philosophical Transactions of the Royal Society a-Mathematical Physical and Engineering Sciences},
    Year = {2003},
    Note = {Ardavan, A Austwick, M Benjamin, SC Briggs, GAD Dennis, TJS Ferguson, A Hasko, DG Kanai, M Khlobystov, AN Lovett, BW Morley, GW Oliver, RA Pettifor, DG Porfyrakis, K Reina, JH Rice, JH Smith, JD Taylor, RA Williams, DA Adelmann, C Mariette, H Hamers, RJ
    Discussion Meeting of the Royal-Society
    Mar 13-14, 2002
    London, england},
    Number = {1808},
    Pages = {1473-1485},
    Volume = {361},
    Abstract = {Most experts agree that it is too early to say how quantum computers will eventually be built, and several nanoscale solid-state schemes are being implemented in a range of materials. Nanofabricated quantum dots can be made in designer configurations, with established technology for controlling interactions and for reading out results. Epitaxial quantum dots can be grown in vertical arrays in semiconductors, and ultrafast optical techniques are available for controlling and measuring their excitations. Single-walled carbon nanotubes can be used for molecular self-assembly of endohedral fullerenes, which can embody quantum information in the electron spin. The challenges of individual addressing in such tiny structures could rapidly become intractable with increasing numbers of qubits, but these schemes are amenable to global addressing methods for computation.},
    Doi = {10.1098/rsta.2003.1214},
    ISSN = {1364-503X},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000184272800014
    http://rsta.royalsocietypublishing.org/content/361/1808/1473.full.pdf}
    }
  • [DOI] Druschel, G. K., R. J. Hamers, G. W. Luther, and J. F. Banfield. Kinetics and mechanism of trithionate and tetrathionate oxidation at low pH by hydroxyl radicals. Aquatic Geochemistry 2003, 9, 145-164.
    [Bibtex]
    @Article{Hamers139,
    Title = {Kinetics and mechanism of trithionate and tetrathionate oxidation at low pH by hydroxyl radicals},
    Author = {Druschel, G. K. and Hamers, R. J. and Luther, G. W. and Banfield, J. F.},
    Journal = {Aquatic Geochemistry},
    Year = {2003},
    Note = {Druschel, GK Hamers, RJ Luther, GW Banfield, JF},
    Number = {2},
    Pages = {145-164},
    Volume = {9},
    Abstract = {The oxidation kinetics of trithionate (S3O62-) and tetrathionate (S4O62-) with hydroxyl radicals (OH*) have been investigated in systems analogous to acid mine drainage (AMD) environments. The discovery of hydroxyl radical (OH*) formation on pyrite surfaces (Borda et al., 2003) suggests hydroxyl radicals may affect the oxidation kinetics of intermediate sulfur species such as tetrathionate. Cyclic voltammetry experiments in acidic solutions indicate that the reaction of S4O62- with OH* goes through an unknown intermediate, tentatively assigned as S3O4n-. An outer-sphere electron transfer mechanism for the reaction of S4O62- with OH* to form S3O4n- is proposed based on experimental results. Oxidation rates for trithionate and tetrathionate in the presence of Fenton's reagent (which forms hydroxyl radicals) are too fast to be directly measured using UV-Vis spectrophotometry, electrochemical, or stop-flow spectrophotometry methods. Competitive reaction kinetics within the context of the Haber-Weiss mechanism suggests that the rate constant for the oxidation of trithionate and tetrathionate with OH* is in excess of 10(8) M-1 sec(-1).},
    Doi = {10.1023/B:AQUA.0000019495.91752.d7},
    ISSN = {1380-6165},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000220170400004
    http://link.springer.com/article/10.1023%2FB%3AAQUA.0000019495.91752.d7}
    }
  • [DOI] Knickerbocker, T., T. Strother, M. P. Schwartz, J. N. Russell, J. Butler, L. M. Smith, and R. J. Hamers. DNA-modified diamond surfaces. Langmuir 2003, 19, 1938-1942.
    [Bibtex]
    @Article{Hamers140,
    Title = {DNA-modified diamond surfaces},
    Author = {Knickerbocker, T. and Strother, T. and Schwartz, M. P. and Russell, J. N. and Butler, J. and Smith, L. M. and Hamers, R. J.},
    Journal = {Langmuir},
    Year = {2003},
    Note = {Knickerbocker, T Strother, T Schwartz, MP Russell, JN Butler, J Smith, LM Hamers, RJ},
    Number = {6},
    Pages = {1938-1942},
    Volume = {19},
    Abstract = {Preparation and hybridization of DNA-modified polycrystalline diamond substrates with fluorescently labeled complementary and noncomplementary oligonucleotide sequences were investigated. Hydrogen-terminated, free-standing diamond substrates were photochemically modified to produce amine-terminated surfaces. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were used to characterize the initial attachment of a protected amine and the subsequent deprotection chemistry. Thiol-terminated DNA oligonucleotides were then linked to the amine-terminated diamond surfaces using a heterobifunctional linker. It is shown that hybridization on DNA-modified polycrystalline diamond is specific, with strong binding of perfectly matched 16-mer complements and little or no binding to 16-mers with 4 mismatched nucleotides. A direct comparison of DNA hybridization on DNA-modified diamond and DNA-modified surfaces of crystalline silicon shows that the diamond surfaces exhibit superior chemical stability under the conditions employed to hybridize and denature the DNA-modified surfaces.},
    Doi = {10.1021/la026279},
    ISSN = {0743-7463},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000181562700006
    http://pubs.acs.org/doi/pdfplus/10.1021/la026279%2B}
    }
  • [DOI] Cao, X. P. and R. J. Hamers. Molecular and dissociative bonding of amines with the Si(111)-(7 x 7) surface. Surface Science 2003, 523, 241-251.
    [Bibtex]
    @Article{Hamers145,
    Title = {Molecular and dissociative bonding of amines with the Si(111)-(7 x 7) surface},
    Author = {Cao, X. P. and Hamers, R. J.},
    Journal = {Surface Science},
    Year = {2003},
    Note = {Cao, XP Hamers, RJ},
    Number = {3},
    Pages = {241-251},
    Volume = {523},
    Abstract = {The interaction of trimethylamine (TMA) and dimethylamine (DMA) with the Si(111)-(7 x 7) surface has been studied by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and ultraviolet photoemission spectroscopy (UPS). STM data for TMA at low coverage show molecular features exhibiting a strong preference for bonding at the center adatom sites. XPS data show that at low coverage the majority of molecules form a highly ionic dative-bonded molecular adduct in which the N atom donates electron density to the surface, leading to a very high N(1s) binding energy of 402.4 eV. UPS data show that the interaction of TMA with the Si(111)-(7 x 7) surface also involves the restatom, suggesting that formation of dative bonds may also alter the restatom state. At very high exposures, a new, dissociative pathway becomes important, leading to dissociation and the appearance of new fragments with lower N(1s) binding energies of 399.1 eV. Corresponding studies for DMA only show dissociative bonding on Si(111), forming H atoms and N(CH3)(2) species. While the N(CH3)(2) species bonds primarily to the adatoms, the H atoms can bond to either adatoms or restatoms. Possible reaction mechanism and the reactivity of the different types of surface silicon atoms are discussed. (C) 2002 Published by Elsevier Science B.V.},
    Doi = {10.1016/s0039-6028(02)02433-0},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000180614600007
    http://www.sciencedirect.com/science/article/pii/S0039602802024330}
    }
  • [DOI] Schwartz, M. P., R. J. Halter, R. J. McMahon, and R. J. Hamers. Formation of an atomically abrupt interface between a polycyclic aromatic molecule and the silicon (001) surface via direct Si-C linkage. Journal of Physical Chemistry B 2003, 107, 224-228.
    [Bibtex]
    @Article{Hamers146,
    Title = {Formation of an atomically abrupt interface between a polycyclic aromatic molecule and the silicon (001) surface via direct Si-C linkage},
    Author = {Schwartz, M. P. and Halter, R. J. and McMahon, R. J. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {2003},
    Note = {Schwartz, MP Halter, RJ McMahon, RJ Hamers, RJ},
    Number = {1},
    Pages = {224-228},
    Volume = {107},
    Abstract = {The reaction of acenaphthylene with the Si(001) surface has been investigated as a model system for understanding how complex pi-systems interact with a pi-bonded semiconductor surface. Scanning tunneling microscopy (STM) reveals that bonding occurs over a dimer row for more than 90% of the adsorbed molecules. Fourier transform infrared spectroscopy (FTIR), using isotopically labeled derivatives of acenaphthylene, shows that bonding occurs through the 1,2-alkene, leaving the aromatic portion of the molecule mostly unperturbed. The reaction between acenaphthylene and Si(001) represents a potential method for coupling extended pi-electron systems with group IV semiconductor surfaces.},
    Doi = {10.1021/jp0265844},
    ISSN = {1520-6106},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000180254900034
    http://pubs.acs.org/doi/pdfplus/10.1021/jp0265844}
    }
  • Baker, S. E., T. L. Lasseter, L. M. Smith, and R. J. Hamers. Covalently-linked Adducts of Single-walled Nanotubes with Biomolecules: Synthesis, Hybridization, and Biologically-Directed Surface Assembly. Materals Research Society Proceedings 2003, 737, F4.6.1.
    [Bibtex]
    @Article{Hamers534,
    Title = {Covalently-linked Adducts of Single-walled Nanotubes with Biomolecules: Synthesis, Hybridization, and Biologically-Directed Surface Assembly},
    Author = {Baker, S.E. and Lasseter, T.L. and Smith, L.M. and Hamers, R.J.},
    Journal = {Materals Research Society Proceedings},
    Year = {2003},
    Pages = {F4.6.1},
    Volume = {737},
    Type = {Journal Article}
    }

2002

  • [DOI] Baker, S. E., W. Cai, T. L. Lasseter, K. P. Weidkamp, and R. J. Hamers. Covalently bonded adducts of deoxyribonucleic acid (DNA) oligonucleotides with single-wall carbon nanotubes: Synthesis and hybridization. Nano Letters 2002, 2, 1413-1417.
    [Bibtex]
    @Article{Hamers148,
    Title = {Covalently bonded adducts of deoxyribonucleic acid (DNA) oligonucleotides with single-wall carbon nanotubes: Synthesis and hybridization},
    Author = {Baker, S. E. and Cai, W. and Lasseter, T. L. and Weidkamp, K. P. and Hamers, R. J.},
    Journal = {Nano Letters},
    Year = {2002},
    Note = {Baker, SE Cai, W Lasseter, TL Weidkamp, KP Hamers, RJ},
    Number = {12},
    Pages = {1413-1417},
    Volume = {2},
    Abstract = {We have developed a multistep route to the formation of covalently linked adducts of single-wall carbon nanotubes (SWNT) and cleoxyribonucleic acid (DNA) oligonucleotides. X-ray photoelectron spectroscopy was used to characterize the initial chemical modification to form amine-terminated SWNTs, which were then covalently linked to DNA. The resulting DNA-SWNT adducts hybridize selectively with complementary sequences, with only minimal interaction with noncomplementary sequences.},
    Doi = {10.1021/nl025729f},
    ISSN = {1530-6984},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000179813700017
    http://pubs.acs.org/doi/pdfplus/10.1021/nl025729f}
    }
  • [DOI] Yang, W. S., O. Auciello, J. E. Butler, W. Cai, J. A. Carlisle, J. Gerbi, D. M. Gruen, T. Knickerbocker, T. L. Lasseter, J. N. Russell, L. M. Smith, and R. J. Hamers. DNA-modified nanocrystalline diamond thin-films as stable, biologically active substrates. Nature Materials 2002, 1, 253-257.
    [Bibtex]
    @Article{Hamers149,
    Title = {DNA-modified nanocrystalline diamond thin-films as stable, biologically active substrates},
    Author = {Yang, W. S. and Auciello, O. and Butler, J. E. and Cai, W. and Carlisle, J. A. and Gerbi, J. and Gruen, D. M. and Knickerbocker, T. and Lasseter, T. L. and Russell, J. N. and Smith, L. M. and Hamers, R. J.},
    Journal = {Nature Materials},
    Year = {2002},
    Note = {Yang, WS Auciello, O Butler, JE Cai, W Carlisle, JA Gerbi, J Gruen, DM Knickerbocker, T Lasseter, TL Russell, JN Smith, LM Hamers, RJ},
    Number = {4},
    Pages = {253-257},
    Volume = {1},
    Abstract = {Diamond, because of its electrical and chemical properties may be a suitable material for integrated sensing and signal processing. But methods to control chemical or biological modifications on diamond surfaces have not been established. Here, we show that nanocrystalline diamond thin-films covalently modified with DNA oligonucleotides provide an extremely stable, highly selective platform in subsequent surface hybridization processes. We used a photochemical modification scheme to chemically modify clean, H-terminated nanocrystalline diamond surfaces grown on silicon substrates, producing a homogeneous layer of amine groups that serve as sites for DNA attachment. After linking DNA to the amine groups, hybridization reactions with fluorescently tagged complementary and non-complementary oligonucleotides showed no detectable non-specific adsorption, with extremely good selectivity between matched and mismatched sequences. Comparison of DNA-modified ultra-nanocrystalline diamond films with other commonly used surfaces for biological modification, such as gold, silicon, glass and glassy carbon, showed that diamond is unique in its ability to achieve very high stability and sensitivity while also being compatible with microelectronics processing technologies. These results suggest that diamond thin-films may be a nearly ideal substrate for integration of microelectronics with biological modification and sensing.},
    Doi = {10.1038/nmat779},
    ISSN = {1476-1122},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000181498800024
    http://www.nature.com/nmat/journal/v1/n4/pdf/nmat779.pdf}
    }
  • [DOI] Schwartz, M. P. and R. J. Hamers. The role of Pi-conjugation in attachment of organic molecules to the silicon (001) surface. Surface Science 2002, 515, 75-86.
    [Bibtex]
    @Article{Hamers150,
    Title = {The role of Pi-conjugation in attachment of organic molecules to the silicon (001) surface},
    Author = {Schwartz, M. P. and Hamers, R. J.},
    Journal = {Surface Science},
    Year = {2002},
    Note = {Schwartz, MP Hamers, RJ},
    Number = {1},
    Pages = {75-86},
    Volume = {515},
    Abstract = {We have investigated the role of conjugation in attachment of multifunctional organic molecules to the Si(001) surface. The model molecules we have chosen are acrylonitrile (CH2=CHCdropN) and allyl cyanide (CH2=CHCH(2)CdropN) due to the electron-withdrawing nature of the cyano, group. X-ray photoelectron spectroscopy shows that significant difference in primary binding configuration exists. Infrared spectroscopy establishes that acrylonitrile attaches to the Si(001) surface primarily through a mechanism involving the cyano group, leading to a novel keteneimine structure that is evidenced by characteristic strong infrared absorbance at 1985 cm(-1). Allyl cyanide adsorbs in a way that principally utilizes the vinyl portion of the molecule, leading mainly to alkane infrared absorbance below 3000 cm(-1). These results show that conjugation can play an important role in controlling product distribution when attaching multifunctional organic molecules to the Si(001) surface. (C) 2002 Published by Elsevier Science B.V.},
    Doi = {10.1016/s0039-6028(02)01807-1},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000177735900012
    http://www.sciencedirect.com/science/article/pii/S0039602802018071}
    }
  • [DOI] Fang, L. A., J. M. Liu, S. Coulter, X. P. Cao, M. P. Schwartz, C. Hacker, and R. J. Hamers. Formation of pi-conjugated molecular arrays on silicon (001) surfaces by heteroatomic Diels-Alder chemistry. Surface Science 2002, 514, 362-375.
    [Bibtex]
    @Article{Hamers151,
    Title = {Formation of pi-conjugated molecular arrays on silicon (001) surfaces by heteroatomic Diels-Alder chemistry},
    Author = {Fang, L. A. and Liu, J. M. and Coulter, S. and Cao, X. P. and Schwartz, M. P. and Hacker, C. and Hamers, R. J.},
    Journal = {Surface Science},
    Year = {2002},
    Note = {Fang, LA Liu, JM Coulter, S Cao, XP Schwartz, MP Hacker, C Hamers, RJ
    57th Yamada Conference on Atomic-Scale Surface Designing for Functional Low-Dimensional Materials
    Nov 14-16, 2001
    Tsukuba, japan
    Si},
    Number = {1-3},
    Pages = {362-375},
    Volume = {514},
    Abstract = {Recent advances in molecular electronics and organic-based electronic materials are placing increased emphasis on developing new methods for attachment of n-conjugated organic molecules to surfaces. We have developed a new strategy for forming oriented arrays of pi-conjugated organic molecules on silicon surfaces. The Si=Si dimers of the reconstructed Si(001) surface can selectivity react with the dicarbonyl group of 9,10-phenanthrenequinone, leading to cyclic molecular structure between the attached molecule and underlying Si substrate. This reaction is formally analogous to a heteroatomic Diels-Alder reaction. X-ray photoemission spectroscopy data show that bonding occurs through the dicarbonyl functional groups, while surface infrared experiment data show that the pi-conjugation is preserved. Ab initio calculations predict that this chemistry leads to aromatic rings that are rigidly attached to the surface, with the aromatic rings oriented perpendicular to the surface and parallel to the underlying Si=Si dimers. This is confirmed by molecular-resolution scanning tunneling microscopy images, which clearly show the orientation of the individual molecules and are even able to resolve the two a lobes on adjacent faces of each vertically oriented molecule. (C) 2002 Published by Elsevier Science B.V.},
    Doi = {10.1016/s0039-6028(02)01654-0},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000177832500056
    http://www.sciencedirect.com/science/article/pii/S0039602802016540}
    }
  • [DOI] Cao, X. P. and R. J. Hamers. Interactions of alkylamines with the silicon (001) surface. Journal of Vacuum Science & Technology B 2002, 20, 1614-1619.
    [Bibtex]
    @Article{Hamers152,
    Title = {Interactions of alkylamines with the silicon (001) surface},
    Author = {Cao, X. P. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology B},
    Year = {2002},
    Note = {Cao, XP Hamers, RJ
    29th Annual Conference on the Physics and Chemistry of Semiconductor Interfaces (PCSI-29)
    Jan 06-10, 2002
    Santa fe, new mexico
    AVS, Electr Mat \& Processing Div, Off Naval Res, Army Res Off},
    Number = {4},
    Pages = {1614-1619},
    Volume = {20},
    Abstract = {The interactions of primary, secondary, and tertiary alkylamines with the Si(001) surface have been investigated using x-ray/ultraviolet photoelectron spectroscopy, Fourier transform infrared spectroscopy and scanning tunneling microscopy. Experimental and computational results show that alkylamines bond to the surface through the nitrogen atom. Primary alkylamines such as hexylamine bond to the surface by breaking only one N-H bond. Secondary alkylamines such as dimethylamine and N-methylpentylamine cleave only the N-H bond, leaving the N-C bonds intact. Tertiary alkylamines, such as trimethylamine and NN-dimethylbutylamine, can form stable dative-bonded adducts on the surface that are characterized by very high N(1s) binding energies of 402.2 eV The ability to form dative-bonded adducts between tertiary alkylamines and Si(001) stems from the capability of electron transfer from nitrogen to the surface. Our results show that this charge exchange controls the propensity for N-H vs N-C bond cleavage. (C) 2002 American Vacuum Society.},
    Doi = {10.1116/1.1490381},
    ISSN = {1071-1023},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000177510500059
    http://avspublications.org/jvstb/resource/1/jvtbd9/v20/i4/p1614_s1
    http://avspublications.org/jvstb/resource/1/jvtbd9/v20/i4/p1614_s1?isAuthorized=no}
    }
  • [DOI] Cai, W., Z. Lin, T. Strother, L. M. Smith, and R. J. Hamers. Chemical modification and patterning of iodine-terminated silicon surfaces using visible light. Journal of Physical Chemistry B 2002, 106, 2656-2664.
    [Bibtex]
    @Article{Hamers155,
    Title = {Chemical modification and patterning of iodine-terminated silicon surfaces using visible light},
    Author = {Cai, W. and Lin, Z. and Strother, T. and Smith, L. M. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {2002},
    Note = {Cai, W Lin, Z Strother, T Smith, LM Hamers, RJ},
    Number = {10},
    Pages = {2656-2664},
    Volume = {106},
    Abstract = {The use of iodine as a photolabile passivating agent for photochemical modification of silicon surfaces is demonstrated. X-ray photoelectron spectroscopy measurements show that iodine termination using iodine dissolved in benzene leads to Si surfaces exhibiting higher iodine surface coverages and lower levels of carbon contamination than previous methods. When exposed to 514 nm light in the presence of a suitable reactive molecule, such as an organic alkene, the surface iodine is removed and the reactive molecule links to the silicon surface. The results of experiments in which the polarization and angle of the incident light were varied show that the reaction mechanism is mediated by absorption of light in the bulk Si. A much greater photoattachment efficiency is obtained on heavily doped n-type silicon than on p-type silicon. It is proposed that on n-type silicon samples the photogenerated minority carriers (holes) accumulate near the surface, making the surface more susceptible to nucleophilic attack by the alkene molecules. The use of this method for photopatterning a Si surface with specific reactive groups is demonstrated.},
    Doi = {10.1021/jp013523h},
    ISSN = {1520-6106},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000174369400032
    http://pubs.acs.org/doi/pdfplus/10.1021/jp013523h}
    }
  • [DOI] Cao, X. P. and R. J. Hamers. Formation of a surface-mediated donor-acceptor complex: Coadsorption of trimethylamine and boron trifluoride on the silicon (001) surface. Journal of Physical Chemistry B 2002, 106, 1840-1842.
    [Bibtex]
    @Article{Hamers156,
    Title = {Formation of a surface-mediated donor-acceptor complex: Coadsorption of trimethylamine and boron trifluoride on the silicon (001) surface},
    Author = {Cao, X. P. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {2002},
    Note = {Cao, XP Hamers, RJ},
    Number = {8},
    Pages = {1840-1842},
    Volume = {106},
    Abstract = {The interaction of trimethylamine and boron trifluoride on the Si(001) surface has been investigated using X-ray photoelectron (XP) spectroscopy. XP spectra show the TMA forms a dative bond with the clean Si(001) surface, while on the clean surface BF3 bonds dissociatively, yielding Si-BF2 and Si-F species. If the surface is first "saturated" with TMA. however, BF3 will continue to adsorb, giving rise to new, F(1s) XP peaks. Based on an analysis of the energies and thermal behavior of these peaks, we propose that the adsorption of TMA and BF3 on the Si(001) surface leads to the formation of a novel surface-mediated donor-acceptor complex of the structure TMA-Si-Si-BF3.},
    Doi = {10.1021/jp013730h},
    ISSN = {1520-6106},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000174189000002
    http://pubs.acs.org/doi/pdfplus/10.1021/jp013730h}
    }
  • [DOI] Strother, T., T. Knickerbocker, J. N. Russell, J. E. Butler, L. M. Smith, and R. J. Hamers. Photochemical functionalization of diamond films. Langmuir 2002, 18, 968-971.
    [Bibtex]
    @Article{Hamers157,
    Title = {Photochemical functionalization of diamond films},
    Author = {Strother, T. and Knickerbocker, T. and Russell, J. N. and Butler, J. E. and Smith, L. M. and Hamers, R. J.},
    Journal = {Langmuir},
    Year = {2002},
    Note = {Strother, T Knickerbocker, T Russell, JN Butler, JE Smith, LM Hamers, RJ},
    Number = {4},
    Pages = {968-971},
    Volume = {18},
    Abstract = {We report a new scheme for attachment of functionalized organic molecules to polycrystalline diamond films. In this scheme, ultraviolet light is used to cause a local reaction between a hydrogen-terminated diamond surface and organic molecules present as a thin overlayer liquid film. Comparison of functionalized alkenes and alkanes shows that alkenes attach more efficiently. By attaching organic molecules with suitable protecting groups and then deprotecting after attachment to the surface, it is possible to prepare diamond surfaces terminated with carboxylic acid groups or with primary amine groups. These functional groups may serve as an attractive starting point for further chemical modification of diamond surfaces.},
    Doi = {10.1021/la0112561},
    ISSN = {0743-7463},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000174009300003
    http://pubs.acs.org/doi/pdfplus/10.1021/la0112561}
    }
  • [DOI] Lin, Z., T. Strother, W. Cai, X. P. Cao, L. M. Smith, and R. J. Hamers. DNA attachment and hybridization at the silicon (100) surface. Langmuir 2002, 18, 788-796.
    [Bibtex]
    @Article{Hamers158,
    Title = {DNA attachment and hybridization at the silicon (100) surface},
    Author = {Lin, Z. and Strother, T. and Cai, W. and Cao, X. P. and Smith, L. M. and Hamers, R. J.},
    Journal = {Langmuir},
    Year = {2002},
    Note = {Lin, Z Strother, T Cai, W Cao, XP Smith, LM Hamers, RJ},
    Number = {3},
    Pages = {788-796},
    Volume = {18},
    Abstract = {The chemical modification of silicon surfaces for DNA attachment and subsequent hybridization has been investigated using X-ray photoelectron spectroscopy and contact angle measurements, in conjunction,with fluorescence-based measurements of DNA hybridization. The feasibility of using small molecules to functionalize Si surfaces with primary amine groups for DNA attachment has been explored using the free amine 1-amino-3-cyclopentene (ACP) and a modified molecule with a protecting group on the amine, N-1-BOC-amino-3-cyclopentene (BACP). Direct attachment of amines leads to chemically heterogeneous surfaces, while the use of suitable protection and deprotection chemistry can produce a homogeneous surface with a high density of primary amine groups. The resulting amine-terminated surfaces were covalently coupled to thio-oligonucleotides using a heterobifunctional cross-linker. Hybridization experiments revealed that these DNA exhibit excellent stability to hybridization conditions, high specificity for recognition, and high density for hybridization, The ability to detect single-base mismatches is demonstrated. Factors controlling the stability, selectivity, and density of surface-bound DNA molecules are discussed.},
    Doi = {10.1021/la010892w},
    ISSN = {0743-7463},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000173646300033
    http://pubs.acs.org/doi/pdfplus/10.1021/la010892w}
    }

2001

  • [DOI] Cao, X. P. and R. J. Hamers. Silicon surfaces as electron acceptors: Dative bonding of amines with Si(001) and Si(111) surfaces. Journal of the American Chemical Society 2001, 123, 10988-10996.
    [Bibtex]
    @Article{Hamers159,
    Title = {Silicon surfaces as electron acceptors: Dative bonding of amines with Si(001) and Si(111) surfaces},
    Author = {Cao, X. P. and Hamers, R. J.},
    Journal = {Journal of the American Chemical Society},
    Year = {2001},
    Note = {Cao, XP Hamers, RJ},
    Number = {44},
    Pages = {10988-10996},
    Volume = {123},
    Abstract = {The bonding of them trimethylamine (TMA) and dimethylamine (DMA) with crystalline silicon surfaces has been investigated using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy, and density-functional computational methods. XPS spectra show that TMA forms stable dative-bonded adducts on both Si(001) and Si(111) surfaces that are characterized by very high N(1s) binding energies of 402.2 eV on Si(001) and 402.4 eV on Si(111). The highly ionic nature of these adducts is further evidenced by comparison with other charge-transfer complexes and through computational chemistry studies. The ability to form these highly ionic charge-transfer complexes between TMA and silicon surfaces stems from the ability to delocalize the donated electron density between different types of chemically distinct atoms within the surface unit cells. Corresponding studies of DMA on Si(001) show only dissociative adsorption via cleavage of the N-H bond. These results show that the unique geometric structures present on silicon surfaces permit silicon atoms to act as excellent electron acceptors.},
    Doi = {10.1021/ja0100322},
    ISSN = {0002-7863},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000172049200025
    http://pubs.acs.org/doi/pdfplus/10.1021/ja0100322}
    }
  • [DOI] Russell, J. N., J. E. Butler, G. T. Wang, S. F. Bent, J. S. Hovis, R. J. Hamers, and M. P. D’Evelyn. pi bond versus radical character of the diamond (100)-2 x 1 surface. Materials Chemistry and Physics 2001, 72, 147-151.
    [Bibtex]
    @Article{Hamers160,
    Title = {pi bond versus radical character of the diamond (100)-2 x 1 surface},
    Author = {Russell, J. N. and Butler, J. E. and Wang, G. T. and Bent, S. F. and Hovis, J. S. and Hamers, R. J. and D'Evelyn, M. P.},
    Journal = {Materials Chemistry and Physics},
    Year = {2001},
    Note = {Russell, JN Butler, JE Wang, GT Bent, SF Hovis, JS Hamers, RJ D'Evelyn, MP
    Taiwan Diamond 2000 Meeting
    Jul 30-aug 02, 2000
    Taipei, taiwan
    Si},
    Number = {2},
    Pages = {147-151},
    Volume = {72},
    Abstract = {The dimers on clean diamond (1 0 0)-2 x 1 are linked by a sigma bond and a highly strained T, bond. The weakness of the surface pi bond causes the reactivity of this surface to be intermediate between that of an alkene and a bi-radical, We illustrate this behavior by investigating two prototypical cycloaddition surface reactions using multiple-internal-reflection infrared spectroscopy. Adsorption of 1,3-butadiene occurs via [4 + 2] addition to surface dimers, analogous to Diels-Alder chemistry of alkenes. However, [2 + 2] cycloaddition of cyclopentene, a reaction that is symmetry-forbidden with alkenes, occurred with a sticking coefficient of similar to 10(-3). These reactions illustrate novel approaches to the functionalization of diamond surfaces. (C) 2001 Elsevier Science B.V. All rights reserved.},
    Doi = {10.1016/s0254-0584(01)00425-4},
    ISSN = {0254-0584},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000171822100010
    http://www.sciencedirect.com/science/article/pii/S0254058401004254}
    }
  • [DOI] Gihring, T. M., G. K. Druschel, R. B. McCleskey, R. J. Hamers, and J. F. Banfield. Rapid arsenite oxidation by Thermus aquaticus and Thermus thermophilus: Field and laboratory investigations. Environmental Science & Technology 2001, 35, 3857-3862.
    [Bibtex]
    @Article{Hamers161,
    Title = {Rapid arsenite oxidation by Thermus aquaticus and Thermus thermophilus: Field and laboratory investigations},
    Author = {Gihring, T. M. and Druschel, G. K. and McCleskey, R. B. and Hamers, R. J. and Banfield, J. F.},
    Journal = {Environmental Science \& Technology},
    Year = {2001},
    Note = {Gihring, TM Druschel, GK McCleskey, RB Hamers, RJ Banfield, JF},
    Number = {19},
    Pages = {3857-3862},
    Volume = {35},
    Abstract = {Thermus aquaticus and Thermus thermophilus, common inhabitants of terrestrial hot springs and thermally polluted domestic and industrial waters, have been found to rapidly oxidize arsenite to arsenate. Field investigations at a hot spring in Yellowstone National Park revealed conserved total arsenic transport and rapid arsenite oxidation occurring within the drainage channel. This environment was heavily colonized by Thermus aquaticus. In laboratory experiments, arsenite oxidation by cultures of Thermus aquaticus YT1 (previously isolated from Yellowstone National Park) and Thermus thermophilus HB8 was accelerated by a factor of over 100 relative to abiotic controls. Thermus aquaticus and Thermus thermophilus may therefore play a large and previously unrecognized role in determining arsenic speciation and bioavailability in thermal environments.},
    Doi = {10.1021/es010816f},
    ISSN = {0013-936X},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000171352500019
    http://pubs.acs.org/doi/pdfplus/10.1021/es010816f}
    }
  • [DOI] Hamers, R. J.. Flexible electronic futures. Nature 2001, 412, 489-490.
    [Bibtex]
    @Article{Hamers162,
    Title = {Flexible electronic futures},
    Author = {Hamers, R. J.},
    Journal = {Nature},
    Year = {2001},
    Note = {Hamers, RJ},
    Number = {6846},
    Pages = {489-490},
    Volume = {412},
    Doi = {10.1038/35087682},
    ISSN = {0028-0836},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000170202900024
    http://www.nature.com/nature/journal/v412/n6846/pdf/412489a0.pdf}
    }
  • [DOI] McGuire, M. M., K. N. Jallad, D. Ben-Amotz, and R. J. Hamers. Chemical mapping of elemental sulfur on pyrite and arsenopyrite surfaces using near-infrared Raman imaging microscopy. Applied Surface Science 2001, 178, 105-115.
    [Bibtex]
    @Article{Hamers164,
    Title = {Chemical mapping of elemental sulfur on pyrite and arsenopyrite surfaces using near-infrared Raman imaging microscopy},
    Author = {McGuire, M. M. and Jallad, K. N. and Ben-Amotz, D. and Hamers, R. J.},
    Journal = {Applied Surface Science},
    Year = {2001},
    Note = {McGuire, MM Jallad, KN Ben-Amotz, D Hamers, RJ},
    Number = {1-4},
    Pages = {105-115},
    Volume = {178},
    Abstract = {Near-infrared Raman imaging microscopy (NIRIM) was used to produce chemical images of the distribution of elemental sulfur on oxidized pyrite and arsenopyrite surfaces. Analysis using Savitsky-Golay filtering permits an unambiguous identification of surface products even in the presence of broad background signals. Rather than forming a continuous, passivating layer at the mineral surface, the NIRIM images reveal that elemental sulfur forms in isolated patches on the order of tens of microns in diameter. The potential implications of this strongly heterogeneous distribution of chemical products for geochemical modeling of acid mine drainage (AMD) are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.},
    Doi = {10.1016/s0169-4332(01)00303-8},
    ISSN = {0169-4332},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000169475300013
    http://www.sciencedirect.com/science/article/pii/S0169433201003038}
    }
  • [DOI] Coulter, S. K., M. P. Schwartz, and R. J. Hamers. Sulfur atoms as tethers for selective attachment of aromatic molecules to silicon(001) surfaces. Journal of Physical Chemistry B 2001, 105, 3079-3087.
    [Bibtex]
    @Article{Hamers166,
    Title = {Sulfur atoms as tethers for selective attachment of aromatic molecules to silicon(001) surfaces},
    Author = {Coulter, S. K. and Schwartz, M. P. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {2001},
    Note = {Coulter, SK Schwartz, MP Hamers, RJ},
    Number = {15},
    Pages = {3079-3087},
    Volume = {105},
    Abstract = {Benzenethiol (C6H5SH) and diphenyl disulfide (C6H5S-SC6H5) were used as model systems to compare the interaction of chemically similar pi -conjugated molecules with the Si(001)-2x1 surface. The bonding behavior of these substituted aromatic hydrocarbons on the Si(001) surface was investigated using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning tunneling microscopy (STM). Both FTIR and XPS indicate that benzenethiol molecules chemisorb on the Si(001) surface predominantly through the sulfur atom via deprotonation-of the thiol substituent group. There also is evidence that a small minority of benzenethiol molecules may adsorb on the surface through the phenyl ring or undergo further fragmentation. Diphenyl disulfide appears to bond to the Si(001) surface in one primary configuration in which the S-S bond of diphenyl disulfide is cleaved and the two sulfur-phenyl moieties are bonded to the silicon surface through the sulfur atoms. Thermal studies indicate that the sulfur-tethered aromatic rings of benzenethiol and diphenyl disulfide are stable to temperatures above 520 K. Furthermore, STM studies show that these molecules chemisorb to the silicon surface within a single dimer row and, in the case of diphenyl disulfide, appear to form ordered rows of sulfur-tethered aromatic rings. This new chemistry demonstrates remarkable potential as a means of selectively attaching pi -conjugated systems to technologically useful semiconductor surfaces.},
    Doi = {10.1021/jp004016n},
    ISSN = {1089-5647},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000168257700032
    http://pubs.acs.org/doi/pdfplus/10.1021/jp004016n}
    }
  • [DOI] McGuire, M. M., K. J. Edwards, J. F. Banfield, and R. J. Hamers. Kinetics, surface chemistry, and structural evolution of microbially mediated sulfide mineral dissolution. Geochimica Et Cosmochimica Acta 2001, 65, 1243-1258.
    [Bibtex]
    @Article{Hamers169,
    Title = {Kinetics, surface chemistry, and structural evolution of microbially mediated sulfide mineral dissolution},
    Author = {McGuire, M. M. and Edwards, K. J. and Banfield, J. F. and Hamers, R. J.},
    Journal = {Geochimica Et Cosmochimica Acta},
    Year = {2001},
    Note = {McGuire, MM Edwards, KJ Banfield, JF Hamers, RJ},
    Number = {8},
    Pages = {1243-1258},
    Volume = {65},
    Abstract = {The effects of different microbial populations on the oxidative dissolution of sulfide minerals at 37 degreesC and pH 1.5 were examined over a period of 22 days. Samples of pyrite, marcasite, and arsenopyrite were exposed to a sulfur-oxidizing isolate (Thiobacillus caldus), an iron-oxidizing isolate (Ferroplasma acidarmanus), and a mixed enrichment culture containing T. caldus. F. acidarmanus, and Leptospirillum ferrooxidans dans. Changes in chemical speciation of the mineral surface products were monitored by Raman spectroscopy over the course of the experiment. structural evolution was examined with scanning electron microscopy, and the total soluble iron was used as a measure of the dissolution rate. In the case of all three minerals, an increase in dissolution rate was observed only in the presence of iron-oxidizing microorganisms (i.e., F. acidarmanus or the enrichment culture). The chemical speciation at the mineral surface in the presence of these iron-oxidizing species is indistinguishable from that of abiotic control reactions under the same conditions; both are dominated by elemental sulfur. In contrast, experiments with T. caldus indicate that the quantity of elemental sulfur on the mineral surface is <1% of the amount observed on samples exposed to the F. acidarmanus culture. It is surprising that removal of the elemental sulfur from the mineral surface by the sulfur-oxidizing species is nor accompanied by an increase in the dissolution rate of the mineral. This finding suggests that although elemental sulfur forms on the surface during oxidative dissolution, it does not passivate the mineral surface. Copyright (C) 2001 Elsevier Science Ltd.},
    Doi = {10.1016/s0016-7037(00)00601-3},
    ISSN = {0016-7037},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000167980600005
    http://www.sciencedirect.com/science/article/pii/S0016703700006013}
    }
  • [DOI] Edwards, K. J., B. Hu, R. J. Hamers, and J. F. Banfield. A new look at microbial leaching patterns on sulfide minerals. Fems Microbiology Ecology 2001, 34, 197-206.
    [Bibtex]
    @Article{Hamers170,
    Title = {A new look at microbial leaching patterns on sulfide minerals},
    Author = {Edwards, K. J. and Hu, B. and Hamers, R. J. and Banfield, J. F.},
    Journal = {Fems Microbiology Ecology},
    Year = {2001},
    Note = {Edwards, KJ Hu, B Hamers, RJ Banfield, JF},
    Number = {3},
    Pages = {197-206},
    Volume = {34},
    Abstract = {Leaching patterns on sulfide minerals were investigated by high-resolution scanning electron microscopy (SEM). Our goal was to evaluate the relative contributions of inorganic surface reactions and reactions localized by attached cells: to surface morphology evolution. Experiments utilized pyrite (FeS2), marcasite (FeS2) and arsenopyrite (FeAsS), and two iron-oxidizing prokaryotes in order to determine the importance of cell typo, crystal structure, and mineral dissolution rate in microbially induced pit formation. Pyrite surfaces were reacted with the iron-oxidizing bactulium Acidithiobacillus ferrooxidans (at 25 degreesC), the iron-oxidizing archoeon 'Ferroplasma acidarmanus' (at 37 degreesC), and abiotically in the presence of Fe3+ ions. In ail three experiments, discrete bacillus-sized (1-2 mum) and -shaped (elliptical) pits developed on pyrite surfaces within 1 week; of reaction. Results show that attaching cells are not necessary fur pit formation on pyrite. Marcasite and arsenopyrite surfaces were reacted with A. ferrooxidans , (at 25 degreesC) and 'F. acidaranus' (at 37 degreesC). Cell-sized and cell-shaped dissolution pits were not observed oil marcasite or arsenopylite at any point during reaction with A. ferrooxidans, or on marcasite surfaces reacted with 'F. acidarmanus'. However, individual 'F. acidarmanus' cells were found within individual shallow (< 0.5 <mu>m deep) pits. The size and shape (round rather than elliptical) of the pits conformed closely to the shape of F. acidarmanus (cells) pits on arsenopyrite. We infer these pits to be cell-induced. We attribute the formation of pits readily detectable (by SEM) to thr higher rt activity of arsenopyrite compared to pyrite and marcasite under the conditions the experiment was conducted. These pits contributed little to the overall surface topographical evolution, and most likely did nor significantly increase surface area during reaction. Our results suggest that overall sulfide mineral dissolution may be dominated by surface reactions with Fe3+ rather than by reactions: at the cell-mineral interface. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.},
    Doi = {10.1111/j.1574-6941.2001.tb00770.x},
    ISSN = {0168-6496},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000166468400003
    http://onlinelibrary.wiley.com/store/10.1111/j.1574-6941.2001.tb00770.x/asset/j.1574-6941.2001.tb00770.x.pdf?v=1&t=hak65bay&s=b03bbdf352dd98babd2e5be5b7d1bcf9a2dde18e}
    }
  • Edwards, C., J. F. Banfield, B. Hu, and R. J. Hamers. A New Look at Bacterial Leaching Patterns on Pyrite. FEMS Microbiol. Ecol 2001, 34, 197-206.
    [Bibtex]
    @Article{Hamers532,
    Title = {A New Look at Bacterial Leaching Patterns on Pyrite},
    Author = {Edwards, C. and Banfield, J. F. and Hu, B. and Hamers, R. J.},
    Journal = {FEMS Microbiol. Ecol},
    Year = {2001},
    Pages = {197-206},
    Volume = {34},
    Type = {Journal Article}
    }
  • Wichaidit, C., J. R. Peck, Z. Lin, R. J. Hamers, S. C. Hagness, and D. W. van der Weide. Resonant slot antennas as transducers of DNA hybridization: a computational feasibility study. IEEE MTT-S International 2001, 1, 163-166.
    [Bibtex]
    @Article{Hamers533,
    Title = {Resonant slot antennas as transducers of DNA hybridization: a computational feasibility study},
    Author = {Wichaidit, C. and Peck, J. R. and Lin, Z. and Hamers, R. J. and Hagness, S.C. and van der Weide, D.W.},
    Journal = {IEEE MTT-S International},
    Year = {2001},
    Pages = {163-166},
    Volume = {1},
    Type = {Journal Article}
    }

2000

  • [DOI] McGuire, M. M. and R. J. Hamers. Extraction and quantitative analysis of elemental sulfur from sulfide mineral surfaces by high-performance liquid chromatography. Environmental Science & Technology 2000, 34, 4651-4655.
    [Bibtex]
    @Article{Hamers171,
    Title = {Extraction and quantitative analysis of elemental sulfur from sulfide mineral surfaces by high-performance liquid chromatography},
    Author = {McGuire, M. M. and Hamers, R. J.},
    Journal = {Environmental Science \& Technology},
    Year = {2000},
    Note = {McGuire, MM Hamers, RJ},
    Number = {21},
    Pages = {4651-4655},
    Volume = {34},
    Abstract = {A simple method for the quantitative determination of elemental sulfur on oxidized sulfide minerals is described. Extraction of elemental sulfur in perchloroethylene and subsequent analysis with high-performance liquid chromatography were used to ascertain the total elemental sulfur resulting from the oxidation of arsenopyrite, pyrite, marcasite, chalcopyrite, and chalcocite under various conditions. An initial pretreatment to remove any sulfur already present on the mineral surface created a chemically clean surface and guaranteed that any elemental sulfur observed was the result of the laboratory oxidation experiments. Because the extraction method and chromatographic analysis are performed ex situ and are not constrained by the parameters of the experimental oxidation reaction, the method can be used for the quantification of elemental sulfur after any laboratory experiment.},
    Doi = {10.1021/es0011663},
    ISSN = {0013-936X},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000165120800049
    http://pubs.acs.org/doi/pdfplus/10.1021/es0011663}
    }
  • [DOI] Strother, T., R. J. Hamers, and L. M. Smith. Covalent attachment of oligodeoxyribonucleotides to amine-modified Si (001) surfaces. Nucleic Acids Research 2000, 28, 3535-3541.
    [Bibtex]
    @Article{Hamers172,
    Title = {Covalent attachment of oligodeoxyribonucleotides to amine-modified Si (001) surfaces},
    Author = {Strother, T. and Hamers, R. J. and Smith, L. M.},
    Journal = {Nucleic Acids Research},
    Year = {2000},
    Note = {Strother, T Hamers, RJ Smith, LM},
    Number = {18},
    Pages = {3535-3541},
    Volume = {28},
    Abstract = {A recently described reaction for the UV-mediated attachment of alkenes to silicon surfaces is utilized as the basis for the preparation of functionalized silicon surfaces, UV tight mediates the reaction of t-butyloxycarbonyl (t-BOC) protected omega-unsaturated aminoalkane (10-aminodec-1-ene) with hydrogen-terminated silicon (001). Removal of the t-BOC protecting group yields an aminodecane-modified silicon surface. The resultant amino groups can be coupled to thiol-modified oligodeoxyribonucleotides using a heterobifunctional crosslinker, permitting the preparation of DNA arrays, Two methods for controlling the surface density of oligodeoxyribonucleotides were explored: in the first, binary mixtures of 10-aminodec-1-ene and dodecene were utilized in the initial UV-mediated coupling reaction; a linear relationship was found between the mole fraction of aminodecene and the density of DNA hybridization sites. In the second, only a portion of the t-BOC protecting groups was removed from the surface by limiting the time allowed for the deprotection reaction, The oligodeoxyribonucleotide-modified surfaces were extremely stable and performed well in DNA hybridization assays. These surfaces provide an alternative to gold or glass for surface immobilization of oligonucleotides in DNA arrays as well as a route for the coupling of nucleic acid biomolecular recognition elements to semiconductor materials.},
    Doi = {10.1093/nar/28.18.3535},
    ISSN = {0305-1048},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000089383500016
    http://nar.oxfordjournals.org/content/28/18/3535.full.pdf}
    }
  • [DOI] Schwartz, M. P., M. D. Ellison, S. K. Coulter, J. S. Hovis, and R. J. Hamers. Interaction of pi-conjugated organic molecules with pi-bonded semiconductor surfaces: Structure, selectivity, and mechanistic implications. Journal of the American Chemical Society 2000, 122, 8529-8538.
    [Bibtex]
    @Article{Hamers173,
    Title = {Interaction of pi-conjugated organic molecules with pi-bonded semiconductor surfaces: Structure, selectivity, and mechanistic implications},
    Author = {Schwartz, M. P. and Ellison, M. D. and Coulter, S. K. and Hovis, J. S. and Hamers, R. J.},
    Journal = {Journal of the American Chemical Society},
    Year = {2000},
    Note = {Schwartz, MP Ellison, MD Coulter, SK Hovis, JS Hamers, RJ},
    Number = {35},
    Pages = {8529-8538},
    Volume = {122},
    Abstract = {The (001) surface of silicon contains pairs of atoms that are held together with a strong sigma bond and a weak pi bond. The interaction of styrene with the Si(001) surface has been investigated as a model system for understanding the interaction of conjugated pi-electron systems to pi-bonded semiconductor surfaces. Scanning tunneling microscopy images show one primary bonding configuration, slightly off-center from the middle of a dimer row. Infrared spectra using isotopically labeled styrene establish that attachment occurs in a highly selective way, bonding through the external vinyl group and leaving the aromatic ring almost completely unperturbed. Ab initio calculations reveal that the interaction between the pi electrons of the vinyl group of styrene and the electron-deficient end of a Si=Si dimer is strongly attractive. It is proposed that this attraction facilitates a low-symmetry interaction between the surface dimers and the vinyl group, leading to a highly selective reaction pathway for which Woodward-Hoffmann rules do not apply. The implications for selective attachment of other conjugated pi-electron systems to other pi-bonded semiconductor surfaces are discussed.},
    Doi = {10.1021/ja000928r},
    ISSN = {0002-7863},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000089285300023
    http://pubs.acs.org/doi/pdfplus/10.1021/ja000928r}
    }
  • [DOI] Hamers, R. J., S. K. Coulter, M. D. Ellison, J. S. Hovis, D. F. Padowitz, M. P. Schwartz, C. M. Greenlief, and J. N. Russell. Cycloaddition chemistry of organic molecules with semiconductor surfaces. Accounts of Chemical Research 2000, 33, 617-624.
    [Bibtex]
    @Article{Hamers174,
    Title = {Cycloaddition chemistry of organic molecules with semiconductor surfaces},
    Author = {Hamers, R. J. and Coulter, S. K. and Ellison, M. D. and Hovis, J. S. and Padowitz, D. F. and Schwartz, M. P. and Greenlief, C. M. and Russell, J. N.},
    Journal = {Accounts of Chemical Research},
    Year = {2000},
    Note = {Hamers, RJ Coulter, SK Ellison, MD Hovis, JS Padowitz, DF Schwartz, MP Greenlief, CM Russell, JN},
    Number = {9},
    Pages = {617-624},
    Volume = {33},
    Abstract = {Recent investigations have shown that cycloaddition reactions, widely used in organic chemistry to form ring compounds, can also be applied to link organic molecules to the (001) surfaces of crystalline silicon, germanium, and diamond. While these surfaces are comprised of Si=Si, Ge=Ge, and C=C structural units that resemble the C=C bonds of organic alkenes, the rates and mechanisms of the surface reactions show some distinct differences from those of their organic counterparts This article reviews recent studies of [2 + 2], [4 + 2] Diels-Alder, and other cycloaddition reactions of organic molecules with semiconductor surfaces and summarizes the current understanding of the reaction pathways.},
    Doi = {10.1021/ar970281o},
    ISSN = {0001-4842},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000089599400005
    http://pubs.acs.org/doi/pdfplus/10.1021/ar970281o}
    }
  • [DOI] Edwards, K. J., P. L. Bond, G. K. Druschel, M. M. McGuire, R. J. Hamers, and J. F. Banfield. Geochemical and biological aspects of sulfide mineral dissolution: lessons from Iron Mountain, California. Chemical Geology 2000, 169, 383-397.
    [Bibtex]
    @Article{Hamers175,
    Title = {Geochemical and biological aspects of sulfide mineral dissolution: lessons from Iron Mountain, California},
    Author = {Edwards, K. J. and Bond, P. L. and Druschel, G. K. and McGuire, M. M. and Hamers, R. J. and Banfield, J. F.},
    Journal = {Chemical Geology},
    Year = {2000},
    Note = {Edwards, KJ Bond, PL Druschel, GK McGuire, MM Hamers, RJ Banfield, JF
    Annual Meeting of the Geological-Society-of-America
    Oct 26-29, 1998
    Toronto, canada
    Geol Soc Amer},
    Number = {3-4},
    Pages = {383-397},
    Volume = {169},
    Abstract = {The oxidative dissolution of sulfide minerals leading to acid mine drainage (AMD) involves a complex interplay between microorganisms, solutions, and mineral surfaces. Consequently, models that link molecular level reactions and the microbial communities that mediate them to field scale processes are few. Here we provide a mini-review of laboratory and field-based studies concerning the chemical, microbial, and kinetic aspects of sulfide mineral dissolution and generation of AMD at the Richmond ore body at Iron Mountain, California. (C) 2000 Elsevier Science B.V. All rights reserved.},
    Doi = {10.1016/s0009-2541(00)00216-3},
    ISSN = {0009-2541},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000089039800011
    http://www.sciencedirect.com/science/article/pii/S0009254100002163}
    }
  • [DOI] Lee, S. W., J. S. Hovis, S. K. Coulter, R. J. Hamers, and C. M. Greenlief. Cycloaddition chemistry on germanium(001) surfaces: the adsorption and reaction of cyclopentene and cyclohexene. Surface Science 2000, 462, 6-18.
    [Bibtex]
    @Article{Hamers176,
    Title = {Cycloaddition chemistry on germanium(001) surfaces: the adsorption and reaction of cyclopentene and cyclohexene},
    Author = {Lee, S. W. and Hovis, J. S. and Coulter, S. K. and Hamers, R. J. and Greenlief, C. M.},
    Journal = {Surface Science},
    Year = {2000},
    Note = {Lee, SW Hovis, JS Coulter, SK Hamers, RJ Greenlief, CM},
    Number = {1-3},
    Pages = {6-18},
    Volume = {462},
    Abstract = {The adsorption and reaction of two cyclic unsaturated hydrocarbons, cyclopentene and cyclohexene, with the Ge(001) surface has been investigated. The subsequent surface interactions were followed by a variety of surface-sensitive techniques. Bonding configurations were determined by photoelectron spectroscopy, infrared spectroscopy and scanning tunneling microscopy. The strength of surface interactions was also monitored by temperature-programmed desorption. Cyclopentene and cyclohexene react with surface germanium-dimer bonds to yield reaction products that are consistent with a [2+2] cycloaddition reaction. This reaction generates rows of the surface complex oriented along the dimer-bond direction of the Ge(001) surface, which is easily observed by scanning tunneling microscopy. (C) 2000 Elsevier Science B.V. All rights reserved.},
    Doi = {10.1016/s0039-6028(00)00622-1},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000088970500006
    http://www.sciencedirect.com/science/article/pii/S0039602800006221}
    }
  • [DOI] Hamers, R. J., J. S. Hovis, S. K. Coulter, M. D. Ellison, and D. F. Padowitz. Ultrathin organic layers on silicon surfaces. Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers 2000, 39, 4366-4371.
    [Bibtex]
    @Article{Hamers177,
    Title = {Ultrathin organic layers on silicon surfaces},
    Author = {Hamers, R. J. and Hovis, J. S. and Coulter, S. K. and Ellison, M. D. and Padowitz, D. F.},
    Journal = {Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes \& Review Papers},
    Year = {2000},
    Note = {Hamers, RJ Hovis, JS Coulter, SK Ellison, MD Padowitz, DF
    3rd International Symposium on Surface Science for Micro- and Nano-device Fabrication (ISSS-3)
    Nov 29-dec 01, 1999
    Tokyo, japan
    Minist Educ, Sci, Sport, \& Culture},
    Number = {7B},
    Pages = {4366-4371},
    Volume = {39},
    Abstract = {Ultrathin organic layers of organic molecules can be produced on the Silicon(001) surface using surface analogs of well-known cycloaddition reactions from organic chemistry. Molecules containing one or more unsaturated C=C can readily bond to the surface at room temperature. Since these reactions form two bonds between the molecule and the surface, the attached molecules are also oriented. More complex molecules containing conjugated pi-electron systems such as styrene can also be bonded to the surface with high selectivity for specific bonds. This manuscript reviews recent progress in forming ultrathin organic layers on silicon, and the current understand of the relevant reaction mechanisms.},
    Doi = {10.1143/jjap.39.4366},
    ISSN = {0021-4922},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000088910000029}
    }
  • [DOI] Coulter, S. K., J. S. Hovis, M. D. Ellison, and R. J. Hamers. Reactions of substituted aromatic hydrocarbons with the Si(001) surface. Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films 2000, 18, 1965-1970.
    [Bibtex]
    @Article{Hamers178,
    Title = {Reactions of substituted aromatic hydrocarbons with the Si(001) surface},
    Author = {Coulter, S. K. and Hovis, J. S. and Ellison, M. D. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology a-Vacuum Surfaces and Films},
    Year = {2000},
    Note = {Coulter, SK Hovis, JS Ellison, MD Hamers, RJ
    46th National Symposium of the American-Vacuum-Society
    Oct 25-29, 1999
    Seattle, washington
    Amer Vacuum Soc
    Part 2},
    Number = {4},
    Pages = {1965-1970},
    Volume = {18},
    Abstract = {The interactions of toluene, para-xylene, meta-xylene and ortho-xylene with the (001) surface of silicon have been investigated using Fourier-transform infrared spectroscopy. Infrared spectra show that these methyl-substituted aromatic hydrocarbons are chemisorbed and oriented on the Si(001) surface at both 110 and 300 K. Peaks in the Si-H stretching region indicate that some dissociation occurs upon adsorption. Comparisons of infrared spectra of these molecules with deuterated and nondeuterated methyl groups reveal that the major source of decomposition is likely from C-H cleavage of the substituent groups, leaving the ring intact. Additionally, the striking similarity of the infrared spectra of benzene, toluene and the xylene isomers suggests that the methyl-substituted aromatic rings interact with the Si(001) surface in much the same way as benzene. Differences in relative peak intensity point to the possibility that the methyl substituent groups may steer the ring into different ratios of specific bonding geometries. (C) 2000 American Vacuum Society. [S0734-2101(00)10404-X].},
    Doi = {10.1116/1.582455},
    ISSN = {0734-2101},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000088277000080
    http://avspublications.org/jvsta/resource/1/jvtad6/v18/i4/p1965_s1
    http://avspublications.org/jvsta/resource/1/jvtad6/v18/i4/p1965_s1?isAuthorized=no}
    }
  • [DOI] Strother, T., W. Cai, X. S. Zhao, R. J. Hamers, and L. M. Smith. Synthesis and characterization of DNA-modified silicon (111) surfaces. Journal of the American Chemical Society 2000, 122, 1205-1209.
    [Bibtex]
    @Article{Hamers183,
    Title = {Synthesis and characterization of DNA-modified silicon (111) surfaces},
    Author = {Strother, T. and Cai, W. and Zhao, X. S. and Hamers, R. J. and Smith, L. M.},
    Journal = {Journal of the American Chemical Society},
    Year = {2000},
    Note = {Strother, T Cai, W Zhao, XS Hamers, RJ Smith, LM},
    Number = {6},
    Pages = {1205-1209},
    Volume = {122},
    Abstract = {Hydrogen-terminated Si(111) surfaces are modified by attachment of oligodeoxynucleotides and characterized with respect to DNA surface density, chemical stability, and DNA hybridization binding specificity. Surface functionalization employs the reaction of omega-unsaturated alkyl esters with the Si(111) surface using UV irradiation. Cleavage of the ester using potassium tert-butoxide yields a carboxyl-modified surface, which serves as a substrate for the attachment of DNA by means of an electrostatically adsorbed layer of polylysine and attachment of thiol-modified DNA using a heterobifunctional cross-linker. The resultant DNA-modified surfaces are shown to exhibit excellent specificity and chemical stability under the conditions of DNA hybridization. This work provides an avenue for the development of devices in which the exquisite binding specificity of biomolecular recognition is directly coupled to semiconductor devices.},
    Doi = {10.1021/ja9936161},
    ISSN = {0002-7863},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000085384200027
    http://pubs.acs.org/doi/pdfplus/10.1021/ja9936161}
    }
  • [DOI] Hovis, J. S., S. K. Coulter, R. J. Hamers, M. P. D’Evelyn, J. N. Russell, and J. E. Butler. Cycloaddition chemistry at surfaces: Reaction of alkenes with the diamond(001)-2 x 1 surface. Journal of the American Chemical Society 2000, 122, 732-733.
    [Bibtex]
    @Article{Hamers184,
    Title = {Cycloaddition chemistry at surfaces: Reaction of alkenes with the diamond(001)-2 x 1 surface},
    Author = {Hovis, J. S. and Coulter, S. K. and Hamers, R. J. and D'Evelyn, M. P. and Russell, J. N. and Butler, J. E.},
    Journal = {Journal of the American Chemical Society},
    Year = {2000},
    Note = {Hovis, JS Coulter, SK Hamers, RJ D'Evelyn, MP Russell, JN Butler, JE},
    Number = {4},
    Pages = {732-733},
    Volume = {122},
    Doi = {10.1021/ja9929077},
    ISSN = {0002-7863},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000085165200032
    http://pubs.acs.org/doi/pdfplus/10.1021/ja9929077}
    }
  • Hamers, R. J. and D. F. Padowitz. 2000. Methods of Tunneling Spectroscopy with the STM. Edited by Bonnell, C.. In Scanning Probe Microscopy: Theory, Techniques, and Applications, 2nd edition, Wiley-VCH Publishers. .
    [Bibtex]
    @InBook{Hamers530,
    Title = {Methods of Tunneling Spectroscopy with the STM},
    Author = {Hamers, R. J. and Padowitz, D. F.},
    Editor = {Bonnell, C.},
    Publisher = {Wiley-VCH Publishers},
    Year = {2000},
    Type = {Book Section},
    Booktitle = {Scanning Probe Microscopy: Theory, Techniques, and Applications, 2nd edition}
    }

1999

  • [DOI] Hovis, J. S., R. J. Hamers, and C. M. Greenlief. Preparation of clean and atomically flat germanium(001) surfaces. Surface Science 1999, 440, L815-L819.
    [Bibtex]
    @Article{Hamers185,
    Title = {Preparation of clean and atomically flat germanium(001) surfaces},
    Author = {Hovis, J. S. and Hamers, R. J. and Greenlief, C. M.},
    Journal = {Surface Science},
    Year = {1999},
    Note = {Hovis, JS Hamers, RJ Greenlief, CM},
    Number = {1-2},
    Pages = {L815-L819},
    Volume = {440},
    Abstract = {A two-part procedure for preparing clean and atomically flat Ge(001)-(2 x 1) surfaces is presented and characterized. The ex situ part of the procedure consists of a wet chemical treatment followed by exposure to ultraviolet-generated ozone. The in situ part of the procedure consists of outgassing for several hours in ultrahigh vacuum followed by flash annealing. Scanning tunneling microscopy shows that the surfaces are flat on the >50 nm length scale and that atomic resolution can be achieved. X-ray photoelectron spectroscopy shows the formation and removal of an oxide layer. It is estimated that approximately 0.02-0.03 monolayers of carbon are present at the annealed surface. (C) 1999 Elsevier Science B.V. All rights reserved.},
    Doi = {10.1016/s0039-6028(99)00866-3},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000083026600003
    http://www.sciencedirect.com/science/article/pii/S0039602899008663}
    }
  • [DOI] Ellison, M. D. and R. J. Hamers. Adsorption of phenyl isothiocyanate on Si(001): A 1,2-dipolar surface addition reaction. Journal of Physical Chemistry B 1999, 103, 6243-6251.
    [Bibtex]
    @Article{Hamers186,
    Title = {Adsorption of phenyl isothiocyanate on Si(001): A 1,2-dipolar surface addition reaction},
    Author = {Ellison, M. D. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {1999},
    Note = {Ellison, MD Hamers, RJ},
    Number = {30},
    Pages = {6243-6251},
    Volume = {103},
    Abstract = {The adsorption of phenyl isothiocyanate (PITC) on silicon (001) surfaces has been investigated using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, scanning tunneling microscopy (STM), and ab initio calculations. The experimental evidence shows that adsorption onto the Si surface occurs in a highly selective manner, through the N=C=S group and not through the benzene ring. Both experimental and theoretical evidence suggests that the adsorption involves the interaction of the N and C atoms of the N=C=S group with the Si=Si dimer, forming a four-member Si2NC ring at the interface. This process leaves the aromatic ring nearly unperturbed and is analogous to a 1,2-dipolar addition reaction. Theoretical calculations confirm that this is the most stable product.},
    Doi = {10.1021/jp990010q},
    ISSN = {1089-5647},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000081813700013
    http://pubs.acs.org/doi/pdfplus/10.1021/jp990010q}
    }
  • [DOI] Zhang, H. Z., R. L. Penn, R. J. Hamers, and J. F. Banfield. Enhanced adsorption of molecules on surfaces of nanocrystalline particles. Journal of Physical Chemistry B 1999, 103, 4656-4662.
    [Bibtex]
    @Article{Hamers187,
    Title = {Enhanced adsorption of molecules on surfaces of nanocrystalline particles},
    Author = {Zhang, H. Z. and Penn, R. L. and Hamers, R. J. and Banfield, J. F.},
    Journal = {Journal of Physical Chemistry B},
    Year = {1999},
    Note = {Zhang, HZ Penn, RL Hamers, RJ Banfield, JF},
    Number = {22},
    Pages = {4656-4662},
    Volume = {103},
    Abstract = {Quantitative measurements of adsorption from solution show up to a 70-fold increase in the adsorption coefficient when a variety of organic acids are adsorbed onto 6 nm compared to 16 nn nanocrystalline titania particles. A Langmuir adsorption model modified to include the dependence of interfacial tension (interfacial free energy) on particle size predicts an increase in the adsorption constant (K-ads) as the crystallite size decreases; in agreement with the experimental results. The increase in K-ads arises predominantly from the increased molar;surface free energy of the nanocrystalline particles. The rapid increase in adsorption as particle size decreases has important implications for understanding and modeling natural and experimental systems.},
    Doi = {10.1021/jp984574q},
    ISSN = {1089-5647},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000080702600014
    http://pubs.acs.org/doi/pdfplus/10.1021/jp984574q}
    }
  • [DOI] Hamers, R. J., J. S. Hovis, C. M. Greenlief, and D. F. Padowitz. Scanning tunneling microscopy of organic molecules and monolayers on silicon and germanium (001) surfaces. Japanese Journal of Applied Physics Part 1-Regular Papers Brief Communications & Review Papers 1999, 38, 3879-3887.
    [Bibtex]
    @Article{Hamers188,
    Title = {Scanning tunneling microscopy of organic molecules and monolayers on silicon and germanium (001) surfaces},
    Author = {Hamers, R. J. and Hovis, J. S. and Greenlief, C. M. and Padowitz, D. F.},
    Journal = {Japanese Journal of Applied Physics Part 1-Regular Papers Brief Communications \& Review Papers},
    Year = {1999},
    Note = {Hamers, RJ Hovis, JS Greenlief, CM Padowitz, DF},
    Number = {6B},
    Pages = {3879-3887},
    Volume = {38},
    Abstract = {High-resolution scanning tunneling microscopy has been used to investigate the adsorption of a variety of unsaturated organic molecules on the (001) surface of silicon and germanium. Results are presented for a number of prototypical alkenes, conjugated and non-conjugated dienes, and aromatic compounds. These include cyclopentene, 1,5-cyclooctadiene: norbarnadiene, 2,3-dimethyl- 1,3-butadiene, and benzene on the Si(001) surface, and for cyclopentene on the Ge(001) surface. Factors controlling the selectivity of various reaction pathways and the consequences for preparation of ordered organic overlayers are discussed.},
    Doi = {10.1143/jjap.38.3879},
    ISSN = {0021-4922},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000081576700021}
    }
  • Edwards, K. J., B. M. Goebel, T. M. Rodgers, M. O. Schrenk, T. M. Gihring, M. M. Cardona, B. Hu, M. M. McGuire, R. J. Hamers, N. R. Pace, and J. F. Banfield. Geomicrobiology of pyrite (FeS2) dissolution: Case study at Iron Mountain, California. Geomicrobiology Journal 1999, 16, 155-179.
    [Bibtex]
    @Article{Hamers189,
    Title = {Geomicrobiology of pyrite (FeS2) dissolution: Case study at Iron Mountain, California},
    Author = {Edwards, K. J. and Goebel, B. M. and Rodgers, T. M. and Schrenk, M. O. and Gihring, T. M. and Cardona, M. M. and Hu, B. and McGuire, M. M. and Hamers, R. J. and Pace, N. R. and Banfield, J. F.},
    Journal = {Geomicrobiology Journal},
    Year = {1999},
    Note = {Edwards, KJ Goebel, BM Rodgers, TM Schrenk, MO Gihring, TM Cardona, MM Hu, B McGuire, MM Hamers, RJ Pace, NR Banfield, JF},
    Number = {2},
    Pages = {155-179},
    Volume = {16},
    Abstract = {Geomicrobiology of pyrite weathering at Iron Mountain, CA, was investigated by molecular biological, surface chemical surface structural, and solution chemical methods in both laboratory and field-based studies. Research focused at sites bath within and peripheral to the ore-body. The acid-generating areas we have examined thus far at Iron Mountain (solution pH < 1.0, temperature > 35 degrees C) were populated by species other than Thiobacillus ferrooxidans. 16S rDNA bacterial sequence analysis and domain- and species-level oligonucleotide probe-based investigations confirmed the presence of planktonic Leptospirillum ferrooxidans and indicated the existence of other species apparently related to other newly described acidophilic chemolithotrophs. T. ferrooxidans was confined to relatively moderate environments (pH 2-3, 20-30 degrees C) that were peripheral to the orebody. Dissolution rate measurements indicated that, per cell, attached and planktonic species contributed comparably in acid release. Surface colonization experiments in the laboratory and field indicated that attachment was specific to sulfides instead of to silicates, occurred in crystallographically preferred orientations and. after cell division, resulted in a monolayer of cells at a maximum density of 8 x 10(6) cells cm(-2). In situ geochemical characterization throughout the year revealed that the microbial community that controlled acid generation varied and could be correlated with seasonal and spatial fluctuations in geochemical conditions.},
    ISSN = {0149-0451},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000081594800002}
    }

1998

  • [DOI] Liu, H. B. and R. J. Hamers. An X-ray photoelectron spectroscopy study of the bonding of unsaturated organic molecules to the Si(001) surface. Surface Science 1998, 416, 354-362.
    [Bibtex]
    @Article{Hamers190,
    Title = {An X-ray photoelectron spectroscopy study of the bonding of unsaturated organic molecules to the Si(001) surface},
    Author = {Liu, H. B. and Hamers, R. J.},
    Journal = {Surface Science},
    Year = {1998},
    Note = {Liu, HB Hamers, RJ},
    Number = {3},
    Pages = {354-362},
    Volume = {416},
    Abstract = {The core-level binding energies of simple unsaturated organic molecules bonded to the Si(001) surface have been investigated using X-ray photoelectron spectroscopy (XPS). Using the Si 2p levels as an internal standard, the shifts in carbon and nitrogen levels were analyzed for a series of small unsaturated molecules, including cyclopentene, ethylene, acetylene, 3-pyrroline and pyrrolidine, adsorbed on the Si(001) surface. Alkene-like carbon atoms are found to have binding energies 0.6-0.9 eV higher than alkane-like molecules. Carbon atoms bonded directly to the silicon surface show binding energies 0.7-0.8 eV lower than those that are not bonded directly to silicon. The N Is binding energy is decreased by 0.9 eV by bonding to silicon. The use of XPS for identification of bonding configurations of unsaturated organic molecules on the silicon (001) surface is discussed. (C) 1998 Published by Elsevier Science B.V. All rights reserved.},
    Doi = {10.1016/s0039-6028(98)00507-x},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000076909400005
    http://www.sciencedirect.com/science/article/pii/S003960289800507X}
    }
  • [DOI] Ellison, M. D., J. S. Hovis, H. B. Liu, and R. J. Hamers. Cycloaddition chemistry on silicon(001) surfaces: The adsorption of azo-tert-butane. Journal of Physical Chemistry B 1998, 102, 8510-8518.
    [Bibtex]
    @Article{Hamers191,
    Title = {Cycloaddition chemistry on silicon(001) surfaces: The adsorption of azo-tert-butane},
    Author = {Ellison, M. D. and Hovis, J. S. and Liu, H. B. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {1998},
    Note = {Ellison, MD Hovis, JS Liu, HB Hamers, RJ},
    Number = {43},
    Pages = {8510-8518},
    Volume = {102},
    Abstract = {The adsorption of azo-tert-butane on the Si(001) surface at 300 K has been investigated using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, scanning tunneling microscopy (STM), and ab initio computational chemistry methods. Although some cleavage of C-H bonds that prevents the formation of a completely ordered layer occurs at room temperature, adsorption onto a 130 K surface occurs molecularly with no bond cleavage. All of the experimental evidence shows that adsorption occurs through the interaction of the N=N azo bond with a single Si=Si dimer bond, in a manner similar to a [2 + 2] cycloaddition reaction. These results show that the use of [2 + 2] cycloaddition reactions to link organic substituents to the Si(001) surface is not limited to alkenes but can be extended to link compounds which have other types of unsaturated bonds to the Si(001) surface.},
    Doi = {10.1021/jp981940x},
    ISSN = {1089-5647},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000076639800024
    http://pubs.acs.org/doi/pdfplus/10.1021/jp981940x}
    }
  • [DOI] Padowitz, D. F. and R. J. Hamers. Voltage-dependent STM images of covalently bound molecules on Si(100). Journal of Physical Chemistry B 1998, 102, 8541-8545.
    [Bibtex]
    @Article{Hamers192,
    Title = {Voltage-dependent STM images of covalently bound molecules on Si(100)},
    Author = {Padowitz, D. F. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {1998},
    Note = {Padowitz, DF Hamers, RJ},
    Number = {43},
    Pages = {8541-8545},
    Volume = {102},
    Abstract = {Several alkenes chemisorbed on silicon(100)-(2 x 1) have been studied by scanning tunneling microscopy. Images of these molecules are strongly bias dependent, typically changing from mounds to depressions as the sample bias voltage is changed from -2.5 to -1.0 V. Image contrast involves both a reduced barrier for tunneling through the molecule and alteration of the silicon surface states by bonding.},
    Doi = {10.1021/jp982229v},
    ISSN = {1089-5647},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000076639800027
    http://pubs.acs.org/doi/pdfplus/10.1021/jp982229v}
    }
  • [DOI] Hovis, J. S., H. B. Liu, and R. J. Hamers. Cycloaddition chemistry of 1,3-dienes on the silicon(001) surface: Competition between 4+2 and 2+2 reactions. Journal of Physical Chemistry B 1998, 102, 6873-6879.
    [Bibtex]
    @Article{Hamers193,
    Title = {Cycloaddition chemistry of 1,3-dienes on the silicon(001) surface: Competition between 4+2 and 2+2 reactions},
    Author = {Hovis, J. S. and Liu, H. B. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {1998},
    Note = {Hovis, JS Liu, HB Hamers, RJ},
    Number = {35},
    Pages = {6873-6879},
    Volume = {102},
    Abstract = {The reactions of 1,3-dienes with the Si(001) surface have been investigated using scanning tunneling microscopy (STM) and Fourier transform infrared spectroscopy (FTIR), and the relative efficiencies of [2 + 2] and [4 + 2] reactions have been determined. STM and FTIR studies show that the 2,3-dimethyl-1,3-butadiene molecule has two bonding configurations; 80% of the molecules bond via a [4 + 2] reaction involving both alkene groups with the remaining 20% bonding via a [2 + 2] reaction involving only one alkene group. The molecule 1,3-cyclohaxadiene shows three separate bonding configurations in the STM, and the FTIR shows at least four separate peaks in the alkene stretching region. The [4 + 2] product is found to comprise 55% of the surface species, the [2 + 2] product 35%, and an unknown product 10%. The surface temperature is found to have little affect on the product distribution. The formation of multiple products and the lack of temperature effects indicate that the product distribution is controlled primarily by the kinetics of the adsorption process, not by the thermodynamics. Thus, although [4 + 2] reactions are predicted to be more stable, [2 + 2] reactions occur nearly as frequently.},
    Doi = {10.1021/jp982286o},
    ISSN = {1089-5647},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000075744000027
    http://pubs.acs.org/doi/pdfplus/10.1021/jp982286o}
    }
  • [DOI] Hovis, J. S., H. Liu, and R. J. Hamers. Cycloaddition chemistry and formation of ordered organic monolayers on silicon (001) surfaces. Surface Science 1998, 402, 1-7.
    [Bibtex]
    @Article{Hamers196,
    Title = {Cycloaddition chemistry and formation of ordered organic monolayers on silicon (001) surfaces},
    Author = {Hovis, J. S. and Liu, H. and Hamers, R. J.},
    Journal = {Surface Science},
    Year = {1998},
    Note = {Hovis, JS Liu, H Hamers, RJ
    17th European Conference on Surface Science
    Sep 16-19, 1997
    Enschede, netherlands},
    Number = {1-3},
    Pages = {1-7},
    Volume = {402},
    Abstract = {It is shown that adsorption of unsaturated organic molecules on the Si(001) surface provides a means for fabricating well-ordered monolayer films at ambient temperatures (approximately 300 K). Two classes of reactions, known as [2 + 2] and [4 + 2] cycloaddition reactions, permit coupling of organic molecules with the Si(001) surface by breaking the weak pi bond of a Si=Si dimer and the pi bond of an organic alkene to produce two Si-C bonds. Experimental results are shown using scanning tunneling microscopy (STM) and Fourier-transform infra-red spectroscopy to investigate the adsorption of cyclopentene, 1,5-cyclooctadiene, and 1,3-cyclohexadiene on Si(001). It is shown that cyclopentene and 1,5-cyclooctadiene bond to the surface via [2 + 2] cycloaddition to produce ordered films. The use of 4 degrees miscut wafers permits the formation of monolayer films exhibiting in-plane anisotropy in optical properties. 1,3-cyclohexadiene bonds via both [2 + 2] and a [4 + 2] Diels-Alder cycloaddition to produce several distinct fragments. (C) 1998 Elsevier Science B.V. All rights reserved.},
    Doi = {10.1016/s0039-6028(98)00031-4},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000074610800002
    http://www.sciencedirect.com/science/article/pii/S0039602898000314}
    }
  • [DOI] Schrenk, M. O., K. J. Edwards, R. M. Goodman, R. J. Hamers, and J. F. Banfield. Distribution of Thiobacillus ferrooxidans and Leptospirillum ferrooxidans: Implications for generation of acid mine drainage. Science 1998, 279, 1519-1522.
    [Bibtex]
    @Article{Hamers197,
    Title = {Distribution of Thiobacillus ferrooxidans and Leptospirillum ferrooxidans: Implications for generation of acid mine drainage},
    Author = {Schrenk, M. O. and Edwards, K. J. and Goodman, R. M. and Hamers, R. J. and Banfield, J. F.},
    Journal = {Science},
    Year = {1998},
    Note = {Schrenk, MO Edwards, KJ Goodman, RM Hamers, RJ Banfield, JF},
    Number = {5356},
    Pages = {1519-1522},
    Volume = {279},
    Abstract = {Although Thiobacillus ferrooxidans and Leptospirillum ferrooxidans are widely considered to be the microorganisms that control the rate of generation of acid mine drainage, little is known about their natural distribution and abundance. Fluorescence in situ hybridization studies showed that at Iron Mountain, California, T. ferrooxidans occurs in peripheral slime-based communities (at pH over 1.3 and temperature under 30 degrees C) but not in important subsurface acid-forming environments (pH 0.3 to 0.7, temperature 30 degrees to 50 degrees C). Leptospirillum ferrooxidans is abundant in slimes and as a planktonic organism in environments with lower pH. Thiobacillus ferrooxidans affects the precipitation of ferric iron solids but plays a limited role in acid generation, and neither species controls direct catalysis at low pH at this site.},
    Doi = {10.1126/science.279.5356.1519},
    ISSN = {0036-8075},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000072372900060
    http://www.sciencemag.org/content/279/5356/1519.full.pdf}
    }
  • [DOI] Hovis, J. S., H. Liu, and R. J. Hamers. Scanning tunneling microscopy of cyclic unsaturated organic molecules on Si(001). Applied Physics a-Materials Science & Processing 1998, 66, S553-S557.
    [Bibtex]
    @Article{Hamers198,
    Title = {Scanning tunneling microscopy of cyclic unsaturated organic molecules on Si(001)},
    Author = {Hovis, J. S. and Liu, H. and Hamers, R. J.},
    Journal = {Applied Physics a-Materials Science \& Processing},
    Year = {1998},
    Note = {Hovis, JS Liu, H Hamers, RJ
    9th International Conference on Scanning Tunneling Microscopy/Spectroscopy and Related Techniques
    Jul 20-25, 1997
    Hamburg, germany
    Free \& Hanseat City Hamburg, German Min Educ Sci Res \& Technol, German Sci Fdn, Commiss European Communities, Oxford Instruments GmbH, Omicron Vakuumphys GmbH, Topometrix GmbH, Digital Instruments
    S
    Part 1},
    Pages = {S553-S557},
    Volume = {66},
    Abstract = {Scanning tunneling microscopy and optical spectroscopy techniques have been utilized to investigate the formation of ordered organic monolayer films on the (001) face of silicon. While norbornadiene produces only disordered films, cyclopentene and 1,5-cyclooctadiene both produce monolayer films that are ordered translationally and rotationally. The rotational orientations of the molecules arise from the directional interaction of the pi orbitals of the starting alkene with the pi orbital of the dimers comprising the reconstructed Si(001) surface, with the Si(001) surface acting as a template for determining the directionality of molecules in the subsequent organic film. Using single-domain Si(001) samples, it is shown that the molecular films also exhibit anisotropy in optical properties when measured on centimeter length scales.},
    Doi = {10.1007/s003390051200},
    ISSN = {0947-8396},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000076887000113
    http://download.springer.com/static/pdf/670/art%253A10.1007%252Fs003390051200.pdf?auth66=1355351015_0bbe174e2b347d2e5cc41008e46e8231&ext=.pdf}
    }
  • Hamers, R. J., J. Hovis, and H. Liu. Scanning tunneling microscopy of ordered organic monolayer films on Si(001). Acta Physica Polonica A 1998, 93, 289-295.
    [Bibtex]
    @Article{Hamers199,
    Title = {Scanning tunneling microscopy of ordered organic monolayer films on Si(001)},
    Author = {Hamers, R. J. and Hovis, J. and Liu, H.},
    Journal = {Acta Physica Polonica A},
    Year = {1998},
    Note = {Hamers, RJ Hovis, J Liu, H
    1st International Symposium on Scanning Probe Spectroscopy and Related Methods (SPS 97)
    Jul 15-19, 1997
    Poznan, poland},
    Number = {2},
    Pages = {289-295},
    Volume = {93},
    Abstract = {Scanning tunneling microscopy and optical spectroscopy techniques have been utilized to investigate the formation of ordered organic monolayer films on the (001) face of silicon. Cyclopentene and 1,5-cyclooctadiene both produce monolayer films that are ordered translationally and rotationally. The rotational orientations of the molecules arise from the directional interaction of the pi orbitals of the starting alkene with the a orbital of the dimers comprising the reconstructed Si(001) surface, with the Si(001) surface acting as a template for determining the directionality of molecules in the subsequent organic film. Using single-domain Si(001) samples, it is shown that the molecular films also exhibit anisotropy in optical properties when measured on centimeter length scales.},
    ISSN = {0587-4246},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000072182700005}
    }
  • Edwards, K. J., M. O. Schrenk, R. J. Hamers, and J. F. Banfield. Microbial oxidation of pyrite: Experiments using microorganisms from an extreme acidic environment. American Mineralogist 1998, 83, 1444-1453.
    [Bibtex]
    @Article{Hamers531,
    Title = {Microbial oxidation of pyrite: Experiments using microorganisms from an extreme acidic environment},
    Author = {Edwards, K.J. and Schrenk, M. O. and Hamers, R. J. and Banfield, J. F.},
    Journal = {American Mineralogist},
    Year = {1998},
    Pages = {1444-1453},
    Volume = {83},
    Type = {Journal Article}
    }

1997

  • [DOI] Frank, E. R. and R. J. Hamers. Chlorine-induced restructuring of Ag(111) films observed by scanning tunneling microscopy. Journal of Catalysis 1997, 172, 406-413.
    [Bibtex]
    @Article{Hamers201,
    Title = {Chlorine-induced restructuring of Ag(111) films observed by scanning tunneling microscopy},
    Author = {Frank, E. R. and Hamers, R. J.},
    Journal = {Journal of Catalysis},
    Year = {1997},
    Note = {Frank, ER Hamers, RJ},
    Number = {2},
    Pages = {406-413},
    Volume = {172},
    Abstract = {The interaction of chlorine (Cl-2) with (111)-textured silver films has been studied using variable-temperature scanning tunneling microscopy. Real-time images reveal that Cl-2 adsorption produces a restructured surface consisting of large terraces separated by microfacets. This restructuring occurs at law chlorine exposures (15 x 10(-7) Torr . S), is observed with a variety of preparation conditions, and is thermally stable up to approximately 830 K. The observed restructuring map partially explain the role of chlorine on the selectivity enhancement observed in the epoxidation of ethylene catalyzed over silver catalysts. (C) 1997 Academic Press.},
    Doi = {10.1006/jcat.1997.1798},
    ISSN = {0021-9517},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:000071256700014
    http://www.sciencedirect.com/science/article/pii/S002195179791798X}
    }
  • [DOI] Hovis, J. S. and R. J. Hamers. Structure and bonding of ordered organic monolayers of 1,5-cyclooctadiene on the silicon(001) surface. Journal of Physical Chemistry B 1997, 101, 9581-9585.
    [Bibtex]
    @Article{Hamers202,
    Title = {Structure and bonding of ordered organic monolayers of 1,5-cyclooctadiene on the silicon(001) surface},
    Author = {Hovis, J. S. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {1997},
    Note = {Hovis, JS Hamers, RJ},
    Number = {46},
    Pages = {9581-9585},
    Volume = {101},
    Abstract = {The interaction of 1,5-cyclooctadiene with the (001) surface of silicon has been investigated using scanning tunneling microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and ab initio computational chemistry techniques. Scanning tunneling microscopy images reveal that 1,5-cyclooctadiene molecules adsorb onto well-defined lattice sites and that the molecules are highly ordered both translationally and rotationally. Fourier-transform infrared and X-ray photoelectron spectra show that bonding occurs without dissociation by breaking one pi bond of the 1,5-cyclooctadiene molecule and the rr bond of one Si=Si dimer of the reconstructed Si(001) surface, forming two new Si-C bonds. Only one of the two unsaturated bonds in each 1,5-cyclooctadiene molecule react, leaving one double bond exposed at the outermost surface. Computational chemistry studies suggest that the surface-bound molecule involves rapid interconversions of several similar low-symmetry conformations.},
    Doi = {10.1021/jp9719826},
    ISSN = {1089-5647},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1997YG46300024
    http://pubs.acs.org/doi/pdfplus/10.1021/jp9719826}
    }
  • [DOI] Liu, H. B. and R. J. Hamers. Stereoselectivity in molecule-surface reactions: Adsorption of ethylene on the silicon(001) surface. Journal of the American Chemical Society 1997, 119, 7593-7594.
    [Bibtex]
    @Article{Hamers203,
    Title = {Stereoselectivity in molecule-surface reactions: Adsorption of ethylene on the silicon(001) surface},
    Author = {Liu, H. B. and Hamers, R. J.},
    Journal = {Journal of the American Chemical Society},
    Year = {1997},
    Note = {Liu, HB Hamers, RJ},
    Number = {32},
    Pages = {7593-7594},
    Volume = {119},
    Doi = {10.1021/ja971452n},
    ISSN = {0002-7863},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1997XR11800029
    http://pubs.acs.org/doi/pdfplus/10.1021/ja971452n}
    }
  • [DOI] Hovis, J. S., S. Lee, H. B. Liu, and R. J. Hamers. Controlled formation of organic layers on semiconductor surfaces. Journal of Vacuum Science & Technology B 1997, 15, 1153-1158.
    [Bibtex]
    @Article{Hamers204,
    Title = {Controlled formation of organic layers on semiconductor surfaces},
    Author = {Hovis, J. S. and Lee, S. and Liu, H. B. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology B},
    Year = {1997},
    Note = {Hovis, JS Lee, S Liu, HB Hamers, RJ
    24th Annual Conference on the Physics and Chemistry of Semiconductor Interfaces (PCSI-24)
    Jan 12-15, 1997
    Res triangle pk, nc},
    Number = {4},
    Pages = {1153-1158},
    Volume = {15},
    Abstract = {It has been shown that well-defined, ordered organic layers can be formed on the silicon (100) surface. This is achieved through the interaction of unsaturated C=C bonds with the oriented dimers of the reconstructed Si(100)-(2 X 1) surface. In this article, we present an investigation of the structure and chemical bonding of organic films prepared using different organic precursors, Data were obtained using scanning tunneling microscopy, Fourier-transform infrared spectroscopy, and x-ray photoelectron spectroscopy. The molecules investigated are cyclopentene, 3-pyrroline, and norbornadiene, representing prototypical cyclic, heterocyclic, and bicyclic unsaturated organic molecules, respectively. Each molecule has at least one unsaturated C=C bond. (C) 1997 American Vacuum Society.},
    Doi = {10.1116/1.589431},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1997XT08800067
    http://avspublications.org/jvstb/resource/1/jvtbd9/v15/i4/p1153_s1
    http://avspublications.org/jvstb/resource/1/jvtbd9/v15/i4/p1153_s1?isAuthorized=no}
    }
  • [DOI] Hamers, R. J., J. S. Hovis, S. Lee, H. B. Liu, and J. Shan. Formation of ordered, anisotropic organic monolayers on the Si(001) surface. Journal of Physical Chemistry B 1997, 101, 1489-1492.
    [Bibtex]
    @Article{Hamers205,
    Title = {Formation of ordered, anisotropic organic monolayers on the Si(001) surface},
    Author = {Hamers, R. J. and Hovis, J. S. and Lee, S. and Liu, H. B. and Shan, J.},
    Journal = {Journal of Physical Chemistry B},
    Year = {1997},
    Note = {Hamers, RJ Hovis, JS Lee, S Liu, HB Shan, J},
    Number = {9},
    Pages = {1489-1492},
    Volume = {101},
    Abstract = {It is shown that the Si=Si dimers of the reconstructed Si(001) surface can react with the pi bonds of unsaturated organic molecules to produce well-defined organic films with novel physical properties. Scanning tunneling microscopy (STM) studies show that the resulting layers are ordered both translationally and rotationally, with the Si=Si dimers acting as a template for extending the translational and rotational order from the silicon substrate to the organic film. STM images and infrared spectroscopy experiments show that by using vicinal Si(001) surface having primarily double-height steps, the rotational order of the molecules can be preserved over macroscopic length scales, leading to measurable anisotropy in optical properties. It is proposed that this chemistry may provide a general method for formation of controlled organic films on Si(001) surfaces.},
    Doi = {10.1021/jp9626778},
    ISSN = {1089-5647},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1997WL35700001
    http://pubs.acs.org/doi/pdfplus/10.1021/jp9626778}
    }
  • Banfield, J. F. and R. J. Hamers. 1997. Processes at minerals and surfaces with relevance to microorganisms and prebiotic synthesis. Edited by Banfield, J. F. and K. H. Nealson. In Geomicrobiology: Interactions between Microbes and Minerals, .
    [Bibtex]
    @InBook{Hamers206,
    Title = {Processes at minerals and surfaces with relevance to microorganisms and prebiotic synthesis},
    Author = {Banfield, J. F. and Hamers, R. J.},
    Editor = {Banfield, J. F. and Nealson, K. H.},
    Pages = {81-122},
    Year = {1997},
    Note = {Banfield, JF Hamers, RJ
    Short Course on Geomicrobiology
    Oct 18-19, 1997
    Alta, ut
    Mineral Soc Amer},
    Series = {Reviews in Mineralogy},
    Type = {Book Section},
    Volume = {35},
    Booktitle = {Geomicrobiology: Interactions between Microbes and Minerals},
    ISBN = {0275-0279
    0-939950-45-6},
    Url = {<Go to ISI>://WOS:A1997BJ74J00003}
    }
  • Banfield, J. F. and R. J. Hamers. Processes At Minerals And Surfaces With Relevance To Microorganisms And Prebiotic Synthesis. Reviews in Mineralogy 1997, 35, 81-122.
    [Bibtex]
    @Article{Hamers529,
    Title = {Processes At Minerals And Surfaces With Relevance To Microorganisms And Prebiotic Synthesis},
    Author = {Banfield, J. F. and Hamers, R. J.},
    Journal = {Reviews in Mineralogy},
    Year = {1997},
    Pages = {81-122},
    Volume = {35},
    Type = {Journal Article}
    }

1996

  • [DOI] Hamers, R. J., Y. J. Wang, and J. Shan. Atomic-level spatial distributions of dopants on silicon surfaces: Toward a microscopic understanding of surface chemical reactivity. Applied Surface Science 1996, 107, 25-34.
    [Bibtex]
    @Article{Hamers207,
    Title = {Atomic-level spatial distributions of dopants on silicon surfaces: Toward a microscopic understanding of surface chemical reactivity},
    Author = {Hamers, R. J. and Wang, Y. J. and Shan, J.},
    Journal = {Applied Surface Science},
    Year = {1996},
    Note = {Hamers, RJ Wang, YJ Shan, J
    3rd International Symposium on Atomically Controlled Surfaces and Interfaces
    Oct 12-14, 1995
    Raleigh, nc},
    Pages = {25-34},
    Volume = {107},
    Abstract = {We have investigated the interaction of phosphine (PH3) and diborane (B2H6) with the Si(001) surface using scanning tunneling microscopy, infrared spectroscopy, and ab initio molecular orbital calculations. Experiment and theory show that the formation of P-Si heterodimers is energetically favorable compared with formation of P-P dimers. The stability of the heterodimers arises from a large strain energy associated with formation of P-P dimers, At moderate P coverages, the formation of P-SI heterodimers leaves the surface with few locations where there are two adjacent reactive sites, This in turn modifies the chemical reactivity toward species such as PH3, which require only one site to adsorb but require two adjacent sites to dissociate. Boron on Si(001) strongly segregates into localized regions of high boron concentration, separated by large regions of clean Si. This leads to a spatially-modulated chemical reactivity which during subsequent growth by chemical vapor deposition (CVD) leads to formation of a rough surface. The implications of the atomic-level spatial distribution of dopants on the rates and mechanisms of CVD growth processes are discussed.},
    Doi = {10.1016/s0169-4332(96)00505-3},
    ISSN = {0169-4332},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1996VV19700006
    http://www.sciencedirect.com/science/article/pii/S0169433296005053}
    }
  • [DOI] Higgins, S. R. and R. J. Hamers. Chemical dissolution of the galena(001) surface observed using electrochemical scanning tunneling microscopy. Geochimica Et Cosmochimica Acta 1996, 60, 3067-3073.
    [Bibtex]
    @Article{Hamers208,
    Title = {Chemical dissolution of the galena(001) surface observed using electrochemical scanning tunneling microscopy},
    Author = {Higgins, S. R. and Hamers, R. J.},
    Journal = {Geochimica Et Cosmochimica Acta},
    Year = {1996},
    Note = {Higgins, SR Hamers, RJ},
    Number = {16},
    Pages = {3067-3073},
    Volume = {60},
    Abstract = {The chemical dissolution of galena(001) surfaces immersed in acidic and neutral sulfate electrolyte solutions was investigated using Electrochemical Scanning Tunneling Microscopy (ECSTM). The nanometer-scale detail provided by the STM in this investigation provides new mechanistic information regarding surface dissolution processes at the mineral/water interface. In acidic solutions (pH = 2.7), we observe that dissolution occurs by selective removal of step edge species. This process is crystallographically anisotropic, resulting in steps with [110] orientations. Under neutral pH conditions (pH = 7), the dissolution rate is significantly lower, and no preferential step edge orientation is observed. The anisotropy observed in acidic solutions is attributed to different kinetic rates of dissolution along the [110] and [100] directions. Furthermore, we propose that the rate limiting step in the dissolution mechanism is the desorption of hydrosulfide (HS-) from step edges. The origin of the crystallographic anisotropy is discussed in terms of possible atomic structures of the step edges.},
    Doi = {10.1016/0016-7037(96)00153-6},
    ISSN = {0016-7037},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1996VC98000010
    http://www.sciencedirect.com/science/article/pii/0016703796001536}
    }
  • [DOI] Hamers, R. J.. Scanned probe microscopies in chemistry. Journal of Physical Chemistry 1996, 100, 13103-13120.
    [Bibtex]
    @Article{Hamers209,
    Title = {Scanned probe microscopies in chemistry},
    Author = {Hamers, R. J.},
    Journal = {Journal of Physical Chemistry},
    Year = {1996},
    Note = {Hamers, RJ},
    Number = {31},
    Pages = {13103-13120},
    Volume = {100},
    Abstract = {The theory and applications of scanned probe microscopies in chemistry are reviewed. The review includes scanning tunneling microscopy (STM), atomic force microscopy (AFM), near-field scanning optical microscopy (NSOM), and other related techniques. Applications to chemical and biochemical imaging, molecular identification, and other systems of importance in chemistry are described.},
    Doi = {10.1021/jp960054o},
    ISSN = {0022-3654},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1996VA59500030
    http://pubs.acs.org/doi/pdfplus/10.1021/jp960054o}
    }
  • [DOI] Hamers, R. J. and Y. J. Wang. Atomically-resolved studies of the chemistry and bonding at silicon surfaces. Chemical Reviews 1996, 96, 1261-1290.
    [Bibtex]
    @Article{Hamers210,
    Title = {Atomically-resolved studies of the chemistry and bonding at silicon surfaces},
    Author = {Hamers, R. J. and Wang, Y. J.},
    Journal = {Chemical Reviews},
    Year = {1996},
    Note = {Hamers, RJ Wang, YJ},
    Number = {4},
    Pages = {1261-1290},
    Volume = {96},
    Doi = {10.1021/cr950213k},
    ISSN = {0009-2665},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1996UU36100004
    http://pubs.acs.org/doi/pdfplus/10.1021/cr950213k}
    }
  • [DOI] Shan, J., Y. J. Wang, and R. J. Hamers. Adsorption and dissociation of phosphine on Si(001). Journal of Physical Chemistry 1996, 100, 4961-4969.
    [Bibtex]
    @Article{Hamers213,
    Title = {Adsorption and dissociation of phosphine on Si(001)},
    Author = {Shan, J. and Wang, Y. J. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry},
    Year = {1996},
    Note = {Shan, J Wang, YJ Hamers, RJ},
    Number = {12},
    Pages = {4961-4969},
    Volume = {100},
    Abstract = {The adsorption and thermal decomposition of phosphine (PH3) on the Si(001) surface has been investigated using Fourier transform infrared spectroscopy. Phosphine is found to adsorb both nondissociatively and dissociatively, depending on the coverage and flux during exposure. Infrared spectra reveal that PH3 dissociates to produce two distinct forms of PH2. Further decomposition yields phosphorus atoms and surface hydrogen. The surface P atoms form P-Si heterodimers and, in the presence of surface hydrogen, form PSiH ''hydrided heterodimers''. The bonding of hydrogen in this form is stronger than on the clean Si surface, resulting in a higher desorption temperature for hydrogen when phosphorus is present on the surface. Molecular orbital calculations are used to provide insight into the bonding geometry of PH3 on Si(001).},
    Doi = {10.1021/jp952452h},
    ISSN = {0022-3654},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1996UB16200041
    http://pubs.acs.org/doi/pdfplus/10.1021/jp952452h}
    }
  • [DOI] Bronikowski, M. J. and R. J. Hamers. The chemistry of gallium deposition on Si(001) from trimethylgallium: An atomically resolved STM study. Surface Science 1996, 348, 311-324.
    [Bibtex]
    @Article{Hamers214,
    Title = {The chemistry of gallium deposition on Si(001) from trimethylgallium: An atomically resolved STM study},
    Author = {Bronikowski, M. J. and Hamers, R. J.},
    Journal = {Surface Science},
    Year = {1996},
    Note = {Bronikowski, MJ Hamers, RJ},
    Number = {3},
    Pages = {311-324},
    Volume = {348},
    Abstract = {The chemistry of trimethylgallium (TMG, Ga(CH3)(3)) and its dissociation fragments on the Si(001) surface has been studied using scanning tunneling microscopy (STM). The products of TMG dissociation are identified by their bonding location with respect to the underlying Si(001) lattice, by bias-dependent imaging and from detailed counting statistics. TMG dissociates at room temperature, yielding a methyl group and a dimethylgallium fragment which bind to the surface. The Ga(CH3)(2) groups produced by TMG dissociation are somewhat mobile at room temperature but are bonded more strongly near surface defects. Further dissociation yields gallium atoms on the surface, but no additional methyl groups. It is proposed that this second stage of reaction involves an intramolecular reaction to produce ethane, which desorbs into the gas phase, and gallium atoms. The gallium atoms are observed to arrange into single rows of gallium dimers which bind epitaxially on the Si surface. Heating the surface to 150 degrees C completely decomposes the DMG fragments, yielding Ga atoms and CH3 groups.},
    Doi = {10.1016/0039-6028(95)01048-3},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1996UA26200012
    http://www.sciencedirect.com/science/article/pii/0039602895010483}
    }
  • Hamers, R. J.. Eighth international conference on scanning tunneling microscopy/spectroscopy and related techniques – Preface. Journal of Vacuum Science & Technology B 1996, 14, 787-787.
    [Bibtex]
    @Article{Hamers215,
    Title = {Eighth international conference on scanning tunneling microscopy/spectroscopy and related techniques - Preface},
    Author = {Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology B},
    Year = {1996},
    Note = {Hamers, RJ},
    Number = {2},
    Pages = {787-787},
    Volume = {14},
    ISSN = {1071-1023},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1996UH89000034}
    }
  • [DOI] Wang, Y. J., J. Shan, and R. J. Hamers. Combined scanning tunneling microscopy and infrared spectroscopy study of the interaction of diborane with Si(001). Journal of Vacuum Science & Technology B 1996, 14, 1038-1042.
    [Bibtex]
    @Article{Hamers216,
    Title = {Combined scanning tunneling microscopy and infrared spectroscopy study of the interaction of diborane with Si(001)},
    Author = {Wang, Y. J. and Shan, J. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology B},
    Year = {1996},
    Note = {Wang, YJ Shan, J Hamers, RJ
    8th International Conference on Scanning Tunneling Microscopy and Related Methods (STM 95)
    Jul 25-29, 1995
    Snowmass, co
    Amer Vacuum Soc, AVS Nanometerscale Sci \& Technol Div, Naval Res Lab, USN, Off Naval Res, USA Res Off, Natl Sci Fdn},
    Number = {2},
    Pages = {1038-1042},
    Volume = {14},
    Abstract = {The atomic-resolution spatial analysis capability of scanning tunneling microscopy is combined with the chemical analysis capability of Fourier transform infrared spectrometry as an integrated approach for atomic scale chemical identification, This approach was tested by studying the adsorption and decomposition of diborane (B2H6) on Si(001). Diborane interacts with Si(001) to produce a metastable B2H5 species, which decomposes into stable surface BH2 units. They further decompose at elevated temperatures; the hydrogen produced can be liberated either onto the surface or into the gas phase, depending on the availability of free Si surface sites, (C) 1996 American Vacuum Society.},
    Doi = {10.1116/1.588450},
    ISSN = {1071-1023},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1996UH89000091
    http://avspublications.org/jvstb/resource/1/jvtbd9/v14/i2/p1038_s1
    http://avspublications.org/jvstb/resource/1/jvtbd9/v14/i2/p1038_s1?isAuthorized=no}
    }
  • [DOI] Chen, X., E. R. Frank, and R. J. Hamers. Spatially and rotationally oriented adsorption of molecular adsorbates on Ag(111) investigated using cryogenic scanning tunneling microscopy. Journal of Vacuum Science & Technology B 1996, 14, 1136-1140.
    [Bibtex]
    @Article{Hamers217,
    Title = {Spatially and rotationally oriented adsorption of molecular adsorbates on Ag(111) investigated using cryogenic scanning tunneling microscopy},
    Author = {Chen, X. and Frank, E. R. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology B},
    Year = {1996},
    Note = {Chen, X Frank, ER Hamers, RJ
    8th International Conference on Scanning Tunneling Microscopy and Related Methods (STM 95)
    Jul 25-29, 1995
    Snowmass, co
    Amer Vacuum Soc, AVS Nanometerscale Sci \& Technol Div, Naval Res Lab, USN, Off Naval Res, USA Res Off, Natl Sci Fdn},
    Number = {2},
    Pages = {1136-1140},
    Volume = {14},
    Abstract = {The molecular adsorption of thiophene and 2,5-dimethylthiophene on Ag(111) surfaces is studied using a cryogenic scanning tunneling microscope (STM) operating at 120 K. Thiophene molecules are observed to adsorb preferentially at step edges, occupying the upper step edge at lowest coverage, and additionally occupying the lower step edge at higher coverage. The adsorption site and rotational orientation of 2.5-dimethylthiophene were identified. Molecules at step edges art: observed to cluster, indicating an attractive interaction between molecules at step edges. As the coverage increases, a phase transition corresponding to a transition from a planar to a tilted geometry is observed. (C) 1996 American Vacuum Society.},
    Doi = {10.1116/1.588415},
    ISSN = {1071-1023},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1996UH89000111
    http://avspublications.org/jvstb/resource/1/jvtbd9/v14/i2/p1136_s1
    http://avspublications.org/jvstb/resource/1/jvtbd9/v14/i2/p1136_s1?isAuthorized=no}
    }
  • [DOI] Higgins, S. R. and R. J. Hamers. Morphology and dissolution processes of metal sulfide minerals observed with the electrochemical scanning tunneling microscope. Journal of Vacuum Science & Technology B 1996, 14, 1360-1364.
    [Bibtex]
    @Article{Hamers218,
    Title = {Morphology and dissolution processes of metal sulfide minerals observed with the electrochemical scanning tunneling microscope},
    Author = {Higgins, S. R. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology B},
    Year = {1996},
    Note = {Higgins, SR Hamers, RJ
    8th International Conference on Scanning Tunneling Microscopy and Related Methods (STM 95)
    Jul 25-29, 1995
    Snowmass, co
    Amer Vacuum Soc, AVS Nanometerscale Sci \& Technol Div, Naval Res Lab, USN, Off Naval Res, USA Res Off, Natl Sci Fdn},
    Number = {2},
    Pages = {1360-1364},
    Volume = {14},
    Abstract = {We report the use of a novel electrochemical scanning tunneling microscope (STM) in the study of surface topography and dissolution phenomena on naturally occurring metal sulfide minerals. Real time dissolution studies of galena in sulfate solution showed that at pH=2.7, the step edges are oriented with outward normal vectors parallel to [110]. Atomic resolution images obtained in acidic perchlorate solution showed single vacancy sites, demonstrating the ability of the STM to resolve individual atomic species under electrolyte solutions. A novel syringe pump system was used to directly determine the effect of chloride ions on the surface structure at the onset of the adsorption process. STM images show the chloride ion produces small pits in the outermost layer of the surface, These observations underscore the importance of anionic species and their effects on the surface topography and dissolution rates. Initial investigations on pyrite and covellite suggest a potentially wide application to metal sulfide minerals. while more detailed investigations on galena illustrate some important aspects of the mineral/electrolyte interface. (C) 1996 American Vacuum Society.},
    Doi = {10.1116/1.589098},
    ISSN = {1071-1023},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1996UH89000161
    http://avspublications.org/jvstb/resource/1/jvtbd9/v14/i2/p1360_s1
    http://avspublications.org/jvstb/resource/1/jvtbd9/v14/i2/p1360_s1?isAuthorized=no}
    }
  • Hamers, R. J., X. Chen, E. R. Frank, S. R. Higgins, J. Shan, and Y. Wang. Atomically-resolved investigations of surface reaction chemistry by scanning tunneling microscopy. Israel Journal of Chemistry 1996, 36, 11-24.
    [Bibtex]
    @Article{Hamers219,
    Title = {Atomically-resolved investigations of surface reaction chemistry by scanning tunneling microscopy},
    Author = {Hamers, R. J. and Chen, X. and Frank, E. R. and Higgins, S. R. and Shan, J. and Wang, Y.},
    Journal = {Israel Journal of Chemistry},
    Year = {1996},
    Note = {Hamers, RJ Chen, X Frank, ER Higgins, SR Shan, J Wang, Y},
    Number = {1},
    Pages = {11-24},
    Volume = {36},
    Abstract = {Research by our group aimed at studying the chemistry of surfaces with atomic-resolution scanning tunneling microscopy is reviewed. Three areas of application are discussed: semiconductor surface chemistry, adsorption processes at metals, and in situ studies of dissolution and oxidation-reduction chemistry of minerals.},
    ISSN = {0021-2148},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1996VN29900003}
    }

1995

  • [DOI] Frank, E. R., X. X. Chen, and R. J. Hamers. DIRECT OBSERVATION OF ORIENTED MOLECULAR ADSORPTION AT STEP EDGES – A CRYOGENIC SCANNING-TUNNELING-MICROSCOPY STUDY. Surface Science 1995, 334, L709-L714.
    [Bibtex]
    @Article{Hamers220,
    Title = {DIRECT OBSERVATION OF ORIENTED MOLECULAR ADSORPTION AT STEP EDGES - A CRYOGENIC SCANNING-TUNNELING-MICROSCOPY STUDY},
    Author = {Frank, E. R. and Chen, X. X. and Hamers, R. J.},
    Journal = {Surface Science},
    Year = {1995},
    Note = {Frank, er chen, xx hamers, rj},
    Number = {1-3},
    Pages = {L709-L714},
    Volume = {334},
    Abstract = {A cryogenic scanning tunneling microscope has been used to investigate the adsorption of thiophene, 2,5-dimethylthiophene, and 2,2'-bithiophene on the Ag(111) surface at 120 K. STM images reveal that all three molecules preferentially bond at step edges. Images of 2,2'-bithiophene and 2,5-dimethylthiophene at the step edge show them to be elongated, while thiophene molecules appear nearly circular. The observed elongation for 2,2'-bithiophene and 2,5-dimethylthiophene is attributed to geometric contrast reflecting the intrinsic shape of these molecules. All molecules of a given chemical identity appear to be oriented in the same direction with respect to the step edge, demonstrating that the interactions between the molecules and the step edge are sufficiently strong and sufficiently local to hold the molecules in specific rotational configurations at the step edge.},
    Doi = {10.1016/0039-6028(95)80021-2},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1995RK97300004
    http://www.sciencedirect.com/science/article/pii/0039602895800212}
    }
  • [DOI] Bronikowski, M. J. and R. J. Hamers. ATOMICALLY RESOLVED SCANNING-TUNNELING-MICROSCOPY STUDY OF THE ADSORPTION AND DISSOCIATION OF METHYLCHLORIDE ON SI(001). Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films 1995, 13, 777-781.
    [Bibtex]
    @Article{Hamers221,
    Title = {ATOMICALLY RESOLVED SCANNING-TUNNELING-MICROSCOPY STUDY OF THE ADSORPTION AND DISSOCIATION OF METHYLCHLORIDE ON SI(001)},
    Author = {Bronikowski, M. J. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology a-Vacuum Surfaces and Films},
    Year = {1995},
    Note = {Bronikowski, mj hamers, rj
    41st National Symposium of the American-Vacuum-Society
    Oct 24-28, 1994
    Denver, co
    Amer Vacuum Soc
    Part 1},
    Number = {3},
    Pages = {777-781},
    Volume = {13},
    Doi = {10.1116/1.579826},
    ISSN = {0734-2101},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1995RD76600054
    http://avspublications.org/jvsta/resource/1/jvtad6/v13/i3/p777_s1
    http://avspublications.org/jvsta/resource/1/jvtad6/v13/i3/p777_s1?isAuthorized=no}
    }
  • [DOI] Wang, Y. J. and R. J. Hamers. BORON-INDUCED RECONSTRUCTIONS OF SI(001) INVESTIGATED BY SCANNING-TUNNELING-MICROSCOPY. Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films 1995, 13, 1431-1437.
    [Bibtex]
    @Article{Hamers222,
    Title = {BORON-INDUCED RECONSTRUCTIONS OF SI(001) INVESTIGATED BY SCANNING-TUNNELING-MICROSCOPY},
    Author = {Wang, Y. J. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology a-Vacuum Surfaces and Films},
    Year = {1995},
    Note = {Wang, yj hamers, rj
    Part 2},
    Number = {3},
    Pages = {1431-1437},
    Volume = {13},
    Doi = {10.1116/1.579682},
    ISSN = {0734-2101},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1995RD76700039
    http://avspublications.org/jvsta/resource/1/jvtad6/v13/i3/p1431_s1
    http://avspublications.org/jvsta/resource/1/jvtad6/v13/i3/p1431_s1?isAuthorized=no}
    }
  • [DOI] Wang, Y. J. and R. J. Hamers. BORON-INDUCED MORPHOLOGY CHANGES IN SILICON CHEMICAL-VAPOR-DEPOSITION – A SCANNING-TUNNELING-MICROSCOPY STUDY. Applied Physics Letters 1995, 66, 2057-2059.
    [Bibtex]
    @Article{Hamers223,
    Title = {BORON-INDUCED MORPHOLOGY CHANGES IN SILICON CHEMICAL-VAPOR-DEPOSITION - A SCANNING-TUNNELING-MICROSCOPY STUDY},
    Author = {Wang, Y. J. and Hamers, R. J.},
    Journal = {Applied Physics Letters},
    Year = {1995},
    Note = {Wang, yj hamers, rj},
    Number = {16},
    Pages = {2057-2059},
    Volume = {66},
    Doi = {10.1063/1.113901},
    ISSN = {0003-6951},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1995QT72800016
    http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=APPLAB000066000016002057000001&idtype=cvips&doi=10.1063/1.113901&prog=normal}
    }
  • [DOI] Higgins, S. R. and R. J. Hamers. SPATIALLY-RESOLVED ELECTROCHEMISTRY OF THE LEAD SULFIDE (GALENA) (001) SURFACE BY ELECTROCHEMICAL SCANNING-TUNNELING-MICROSCOPY. Surface Science 1995, 324, 263-281.
    [Bibtex]
    @Article{Hamers226,
    Title = {SPATIALLY-RESOLVED ELECTROCHEMISTRY OF THE LEAD SULFIDE (GALENA) (001) SURFACE BY ELECTROCHEMICAL SCANNING-TUNNELING-MICROSCOPY},
    Author = {Higgins, S. R. and Hamers, R. J.},
    Journal = {Surface Science},
    Year = {1995},
    Note = {Higgins, sr hamers, rj},
    Number = {2-3},
    Pages = {263-281},
    Volume = {324},
    Abstract = {Electrochemical scanning tunneling microscopy (STM) has been used to investigate the chemical and electrochemical reactions of naturally-occurring lead sulfide (galena) (001) surfaces. Both oxidation and reduction reactions are shown to be spatially anisotropic, involving almost exclusively atoms located at step edges. STM images show that the oxidation reaction PbS --> Pb2+ + S + 2e(-) occurs by removal of atoms from step edges, and that impurity-related defects on the surface lead to etch pit formation under oxidizing conditions. STM images at ambient lead concentrations reveal that the electrochemical reduction PbS + 2H(+) 2e(-) --> Pb-0 + H2S occurs exclusively by removal of material from step edges, with simultaneous 2 formation of Pb(111) islands on the PbS terraces. Re-oxidation of the Pb islands causes regrowth of PbS at the step edges and the simultaneous disappearance of Pb islands from the terraces, indicating that this reaction is partially reversible at the atomic level. Using atomic-resolution images to establish the crystallographic orientation, it is shown that the rate of removal of material from step edges is directionally anisotropic and is fastest along the [100] directions, leaving behind steps with outward normal directed along the equivalent [110] directions.},
    Doi = {10.1016/0039-6028(94)00700-4},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1995QG63800021
    http://www.sciencedirect.com/science/article/pii/0039602894007004}
    }
  • [DOI] Wang, Y. J., R. J. Hamers, and E. Kaxiras. ATOMIC-STRUCTURE AND BONDING OF BORON-INDUCED RECONSTRUCTIONS ON SI(001). Physical Review Letters 1995, 74, 403-406.
    [Bibtex]
    @Article{Hamers227,
    Title = {ATOMIC-STRUCTURE AND BONDING OF BORON-INDUCED RECONSTRUCTIONS ON SI(001)},
    Author = {Wang, Y. J. and Hamers, R. J. and Kaxiras, E.},
    Journal = {Physical Review Letters},
    Year = {1995},
    Note = {Wang, yj hamers, rj kaxiras, e},
    Number = {3},
    Pages = {403-406},
    Volume = {74},
    Doi = {10.1103/PhysRevLett.74.403},
    ISSN = {0031-9007},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1995QB16400017
    http://prl.aps.org/abstract/PRL/v74/i3/p403_1}
    }

1994

  • [DOI] Chen, X., E. R. Frank, and R. J. Hamers. AN ATOMIC-RESOLUTION CRYOGENIC SCANNING TUNNELING MICROSCOPE. Review of Scientific Instruments 1994, 65, 3373-3377.
    [Bibtex]
    @Article{Hamers228,
    Title = {AN ATOMIC-RESOLUTION CRYOGENIC SCANNING TUNNELING MICROSCOPE},
    Author = {Chen, X. and Frank, E. R. and Hamers, R. J.},
    Journal = {Review of Scientific Instruments},
    Year = {1994},
    Note = {Chen, x frank, er hamers, rj},
    Number = {11},
    Pages = {3373-3377},
    Volume = {65},
    Doi = {10.1063/1.1144575},
    ISSN = {0034-6748},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1994PT16400009
    http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=RSINAK000065000011003373000001&idtype=cvips&doi=10.1063/1.1144575&prog=normal}
    }
  • [DOI] Wang, Y. J., X. X. Chen, and R. J. Hamers. ATOMIC-RESOLUTION STUDY OF OVERLAYER FORMATION AND INTERFACIAL MIXING IN THE INTERACTION OF PHOSPHORUS WITH SI(001). Physical Review B 1994, 50, 4534-4547.
    [Bibtex]
    @Article{Hamers230,
    Title = {ATOMIC-RESOLUTION STUDY OF OVERLAYER FORMATION AND INTERFACIAL MIXING IN THE INTERACTION OF PHOSPHORUS WITH SI(001)},
    Author = {Wang, Y. J. and Chen, X. X. and Hamers, R. J.},
    Journal = {Physical Review B},
    Year = {1994},
    Note = {Wang, yj chen, xx hamers, rj},
    Number = {7},
    Pages = {4534-4547},
    Volume = {50},
    Abstract = {Scanning tunneling microscopy (STM), tunneling spectroscopy, and Auger-electron spectroscopy have been used to study the formation of phosphorus-terminated silicon (001) surfaces by the thermal decomposition of phosphine (PH3). The STM images show that surface phosphorus atoms readily displace Si from the substrate, dramatically changing the overall surface morphology through the formation of large numbers of islands and an extreme roughening of step edges. The surfaces are terminated with P-P dimers, but also contain large numbers of line defects which act as a strain relief mechanism. STM images are used to determine the symmetry of these line defects and are compared with model defect structures. Line defects in the phosphorus-terminated surface both nucleate islands and also constrain their growth in one dimension, such that the phosphorus-terminated surfaces contain large numbers of extremely anisotropic islands and very rough step edges. At lower phosphorus coverage, the STM experiments are able to identify Si and P atoms individually, revealing the formation of large numbers of Si-P heterodimers and the simultaneous disappearance of the strain-induced line defects. Counting statistics are used to study the equilibrium between Si=Si, Si-P, and P-P dimers, showing that the surface is a nearly random alloy with a slight nonstatistical preference for formation of the Si-P heterodimer. The geometric and electronic properties of Si=Si, Si-P, and P-P dimers on Si(001) are discussed on the basis of tunneling microscopy and tunneling spectroscopy measurements.},
    Doi = {10.1103/PhysRevB.50.4534},
    ISSN = {0163-1829},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1994PD75300033
    http://prb.aps.org/abstract/PRB/v50/i7/p4534_1}
    }
  • [DOI] Wang, Y. J., M. J. Bronikowski, and R. J. Hamers. DIRECT DIMER-BY-DIMER IDENTIFICATION OF CLEAN AND MONOHYDRIDE DIMERS ON THE SI(001) SURFACE BY SCANNING-TUNNELING-MICROSCOPY. Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films 1994, 12, 2051-2057.
    [Bibtex]
    @Article{Hamers231,
    Title = {DIRECT DIMER-BY-DIMER IDENTIFICATION OF CLEAN AND MONOHYDRIDE DIMERS ON THE SI(001) SURFACE BY SCANNING-TUNNELING-MICROSCOPY},
    Author = {Wang, Y. J. and Bronikowski, M. J. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology a-Vacuum Surfaces and Films},
    Year = {1994},
    Note = {Wang, yj bronikowski, mj hamers, rj
    Part 2},
    Number = {4},
    Pages = {2051-2057},
    Volume = {12},
    Abstract = {Atomic resolution images of clean Si(001)-(2x1) and the monohydride phase, Si(001)-(2X1)H were investigated using scanning tunneling microscopy at various sample-tip bias voltages. At a sample-tip bias of -1.9 V, each dimer of the monohydride phase shows two protrusions 3.3 angstrom apart separated by a minimum 0.12 angstrom deep, while clean dimers show a single protrusion per unit cell. Monohydride dimers appear lower than ''clean'' dimers, with apparent height differences ranging from 1.9 angstrom at -1.6 V to 0.65 angstrom at -3.0 V sample bias. An analysis of the apparent height and spatial distribution of tunneling current within each dimer can be used to unambiguously discriminate between clean dimers, monohydride dimers, and vacancy defects. This methodology is applied to study the distribution of hydrogen on Si(001) surfaces during chemical vapor deposition using disilane, revealing segregation of the monohydride into nearly isotropic islands.},
    Doi = {10.1116/1.579135},
    ISSN = {0734-2101},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1994NZ03200045
    http://avspublications.org/jvsta/resource/1/jvtad6/v12/i4/p2051_s1
    http://avspublications.org/jvsta/resource/1/jvtad6/v12/i4/p2051_s1?isAuthorized=no}
    }
  • [DOI] Chen, X. X., E. R. Frank, and R. J. Hamers. ADSORPTION OF SULFUR AND 1,3-BUTANEDIOL ON SILVER THIN-FILMS USING ATOMIC RESOLUTION-REDUCED-TEMPERATURE SCANNING-TUNNELING-MICROSCOPY. Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films 1994, 12, 2091-2096.
    [Bibtex]
    @Article{Hamers232,
    Title = {ADSORPTION OF SULFUR AND 1,3-BUTANEDIOL ON SILVER THIN-FILMS USING ATOMIC RESOLUTION-REDUCED-TEMPERATURE SCANNING-TUNNELING-MICROSCOPY},
    Author = {Chen, X. X. and Frank, E. R. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology a-Vacuum Surfaces and Films},
    Year = {1994},
    Note = {Chen, xx frank, er hamers, rj
    Part 2},
    Number = {4},
    Pages = {2091-2096},
    Volume = {12},
    Abstract = {Scanning tunneling microscopy has been used to study the adsorption of atomic sulfur and 1,3-butanediol on silver films formed by evaporation onto Si(111)-(7X7) substrates. Thin silver films only a few monolayers thick grown on Si(111) show a square-root 3 X square-root 3 R30-degrees reconstruction, while thicker films show a hexagonal close-packed, unreconstructed Ag(111) surface. At high deposition rates, screw dislocations in die films are commonly observed. Atomic sulfur adsorbed on thin Ag films showing a square-root 3 X square-root 3 R30-degrees reconstruction appears as a protrusion when filled states are imaged and as a depression in empty state images. The sulfur atoms bond almost exclusively at lattice defects which appear to be vacancy clusters. 1,3-butanediol appears as a large depression at all biases, indicating that the adsorbate electrostatically repels charge and lowers the metal density of states around the adsorption site.},
    Doi = {10.1116/1.579142},
    ISSN = {0734-2101},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1994NZ03200052
    http://avspublications.org/jvsta/resource/1/jvtad6/v12/i4/p2091_s1
    http://avspublications.org/jvsta/resource/1/jvtad6/v12/i4/p2091_s1?isAuthorized=no}
    }
  • [DOI] Wang, Y. J., M. J. Bronikowski, and R. J. Hamers. AN ATOMICALLY RESOLVED STM STUDY OF THE INTERACTION OF PHOSPHINE WITH THE SILICON(001) SURFACE. Journal of Physical Chemistry 1994, 98, 5966-5973.
    [Bibtex]
    @Article{Hamers233,
    Title = {AN ATOMICALLY RESOLVED STM STUDY OF THE INTERACTION OF PHOSPHINE WITH THE SILICON(001) SURFACE},
    Author = {Wang, Y. J. and Bronikowski, M. J. and Hamers, R. J.},
    Journal = {Journal of Physical Chemistry},
    Year = {1994},
    Note = {Wang, yj bronikowski, mj hamers, rj},
    Number = {23},
    Pages = {5966-5973},
    Volume = {98},
    Abstract = {The interaction of phosphine (PH3) with the Si(001) surface has been investigated with scanning tunneling microscopy. At 300 K, PH3 adsorbs molecularly on top of a single Si=Si dimer with the phosphorus atom in a pentacoordinate configuration. Phosphine adsorption is accompanied by occasional ejection of silicon atoms from the substrate onto the surface, creating surface vacancies and Si adatoms. Si atoms are preferentially ejected from defect sites. At high coverage, adsorbed PH3 molecules order into small regions of c(4X2) symmetry, and the ejected silicon nucleates into small dimer strings. The long-range order of the molecular PH3 is disrupted by domain boundaries and the ejected silicon. Annealing PH3-saturated surfaces produces further ejection of silicon onto the surface, resulting in large silicon islands covering approximately 20% of the surface.},
    Doi = {10.1021/j100074a025},
    ISSN = {0022-3654},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1994NQ72500025
    http://pubs.acs.org/doi/pdf/10.1021/j100074a025}
    }
  • [DOI] Wang, Y. J., M. J. Bronikowski, and R. J. Hamers. AN ATOMICALLY RESOLVED SCANNING-TUNNELING-MICROSCOPY STUDY OF THE THERMAL-DECOMPOSITION OF DISILANE ON SI(001). Surface Science 1994, 311, 64-100.
    [Bibtex]
    @Article{Hamers234,
    Title = {AN ATOMICALLY RESOLVED SCANNING-TUNNELING-MICROSCOPY STUDY OF THE THERMAL-DECOMPOSITION OF DISILANE ON SI(001)},
    Author = {Wang, Y. J. and Bronikowski, M. J. and Hamers, R. J.},
    Journal = {Surface Science},
    Year = {1994},
    Note = {Wang, yj bronikowski, mj hamers, rj},
    Number = {1-2},
    Pages = {64-100},
    Volume = {311},
    Abstract = {Scanning tunneling microscopy (STM) has been used to study the adsorption and thermal dissociation of disilane (Si2H6) on the Si(001) surface. At low coverage, disilane adsorbs dissociatively to produce adsorbed SiH3 groups which are randomly distributed on the surface. STM images show that these SiH3 groups spontaneously dissociate into SiH2 and H within several minutes of adsorption at room temperature, and images depicting individual dissociation events have been obtained. Thermal annealing leads to diffusion and dissociation of the SiH2 groups through an intermediate which consists of a hydrogenated dimer which has its dimer axis parallel to those of the underlying substrate, instead of rotated. The structure and chemical identity of the intermediates are discussed in terms of the overall dissociation mechanism. Diffusion of hydrogen atoms leads to the formation of segregated surface phase of clean Si and the Si(001)-(2 x 1) ''monohydride'' structure, and bias-dependent STM imaging permits these species to be identified on a dimer-by-dimer basis. At low temperatures the monohydride distribution is non-statistical, showing a preference for flat terraces over small epitaxial islands. The diffusion, desorption, segregation of hydrogen and its role in blocking diffusion of silicon atoms is also discussed.},
    Doi = {10.1016/0039-6028(94)90481-2},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1994NL43100017
    http://www.sciencedirect.com/science/article/pii/0039602894904812}
    }

1993

  • [DOI] Bronikowski, M. J., Y. J. Wang, M. T. McEllistrem, D. Chen, and R. J. Hamers. ADSORPTION AND DISSOCIATION OF DISILANE ON SI(001) STUDIED BY STM. Surface Science 1993, 298, 50-62.
    [Bibtex]
    @Article{Hamers237,
    Title = {ADSORPTION AND DISSOCIATION OF DISILANE ON SI(001) STUDIED BY STM},
    Author = {Bronikowski, M. J. and Wang, Y. J. and McEllistrem, M. T. and Chen, D. and Hamers, R. J.},
    Journal = {Surface Science},
    Year = {1993},
    Note = {Bronikowski, mj wang, yj mcellistrem, mt chen, d hamers, rj},
    Number = {1},
    Pages = {50-62},
    Volume = {298},
    Abstract = {The surface-adsorbed fragments resulting from the room-temperature adsorption and dissociation of disilane (Si2H6) on Si(001) are observed and identified using scanning tunneling microscopy (STM). The predominant fragments are H and SiH2, which are identified by the symmetries of their binding sites on the surface. H atoms often bind near single or double dimer vacancy defects. We find that adsorbed H atoms induce buckling of the dimer rows on the Si(001) surface, while SiH2 groups do not. This difference is ascribed to differences in the electronic structure of the two surface-bound species. No systematic correlation between the positions of the SiH2 groups is evident, which indicates that the fragments of a single disilane molecule are not localized in a small region. This fact suggests that at least some of the molecular fragments from disilane dissociation are mobile on the Si(001) surface at room temperature. Further decomposition of the SiH2 fragments can be induced by annealing, which produces surface structures similar to those seen in molecular-beam epitaxial growth of silicon: small asymmetric islands form with low disilane coverages, whereas higher coverages give multilayer island growth.},
    Doi = {10.1016/0039-6028(93)90079-y},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1993ML07900013
    http://www.sciencedirect.com/science/article/pii/003960289390079Y}
    }
  • [DOI] Bronikowski, M. J., Y. J. Wang, and R. J. Hamers. ANTIPHASE BOUNDARIES AS NUCLEATION CENTERS IN LOW-TEMPERATURE SILICON EPITAXIAL-GROWTH. Physical Review B 1993, 48, 12361-12364.
    [Bibtex]
    @Article{Hamers238,
    Title = {ANTIPHASE BOUNDARIES AS NUCLEATION CENTERS IN LOW-TEMPERATURE SILICON EPITAXIAL-GROWTH},
    Author = {Bronikowski, M. J. and Wang, Y. J. and Hamers, R. J.},
    Journal = {Physical Review B},
    Year = {1993},
    Note = {Bronikowski, mj wang, yj hamers, rj},
    Number = {16},
    Pages = {12361-12364},
    Volume = {48},
    Abstract = {The epitaxial growth of silicon on Si(001) from disilane at 720 K has been investigated using scanning tunneling microscopy. Epitaxy occurs by island nucleation and growth, with islands nucleating preferentially at antiphase boundaries between different regions on the substrate terraces. These islands begin as a single dimer string which grows to cover the entire antiphase boundary before lateral growth begins. The islands increase in size until they meet on the surface, forming new antiphase boundaries (50% of the time) for nucleation of the next layer. We find that islands nucleated at such boundaries account for approximately 94% of the area of a growing layer, indicating that essentially all epitaxial growth at this temperature occurs by this mechanism.},
    Doi = {10.1103/PhysRevB.48.12361},
    ISSN = {0163-1829},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1993ME60100113
    http://prb.aps.org/abstract/PRB/v48/i16/p12361_1}
    }
  • [DOI] McEllistrem, M., G. Haase, D. Chen, and R. J. Hamers. ELECTROSTATIC SAMPLE-TIP INTERACTIONS IN THE SCANNING TUNNELING MICROSCOPE. Physical Review Letters 1993, 70, 2471-2474.
    [Bibtex]
    @Article{Hamers239,
    Title = {ELECTROSTATIC SAMPLE-TIP INTERACTIONS IN THE SCANNING TUNNELING MICROSCOPE},
    Author = {McEllistrem, M. and Haase, G. and Chen, D. and Hamers, R. J.},
    Journal = {Physical Review Letters},
    Year = {1993},
    Note = {Mcellistrem, m haase, g chen, d hamers, rj},
    Number = {16},
    Pages = {2471-2474},
    Volume = {70},
    Abstract = {Local surface photovoltage (SPV) measurements were used to measure how the electric field of a scanning tunneling microscope tip perturbs the electronic band structure at Si(001), Si(111)-(7 x 7), and H-terminated Si(111) surfaces. The results demonstrate that tip-induced band bending is important under typical STM conditions even on surfaces whose surface Fermi levels are nominally ''pinned.'' Spatially resolved measurements of band bending as a function of sample bias show that atomic-scale contrast in SPV images can result from local variations in the ability of the surface states under the tip to screen external electric fields.},
    Doi = {10.1103/PhysRevLett.70.2471},
    ISSN = {0031-9007},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1993KX81500029
    http://prl.aps.org/abstract/PRL/v70/i16/p2471_1}
    }
  • Hamers, R. J.. 1993. Tunneling Spectroscopy. In Scanning Tunneling Microscopy, VCH Publishers. .
    [Bibtex]
    @InBook{Hamers519,
    Title = {Tunneling Spectroscopy},
    Author = {Hamers, R.J.},
    Publisher = {VCH Publishers},
    Year = {1993},
    Type = {Book Section},
    Booktitle = {Scanning Tunneling Microscopy}
    }

1992

  • Cahill, D. G. and R. J. Hamers. CHARGE DYNAMICS AT THE SILICON(001) SURFACE STUDIED BY SCANNING TUNNELING MICROSCOPY AND SURFACE PHOTOVOLTAGE. Scanning Microscopy 1992, 6, 931-936.
    [Bibtex]
    @Article{Hamers240,
    Title = {CHARGE DYNAMICS AT THE SILICON(001) SURFACE STUDIED BY SCANNING TUNNELING MICROSCOPY AND SURFACE PHOTOVOLTAGE},
    Author = {Cahill, D. G. and Hamers, R. J.},
    Journal = {Scanning Microscopy},
    Year = {1992},
    Note = {Cahill, dg hamers, rj},
    Number = {4},
    Pages = {931-936},
    Volume = {6},
    Abstract = {Scanning tunneling microscopy measurements of local surface photovoltage of the Si(001) surface reveal the existence of local charging produced by the tunneling current. Since the tunneling current is. confined to a region of near atomic dimensions, charge transport between surface and bulk electronic states is probed with high spatial resolution. The surface charge is enhanced while tunneling at the bonded, type-B atomic step and at specific point defects demonstrating atomic-scale variations in the charge dynamics.},
    ISSN = {0891-7035},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1992KK54800006}
    }
  • [DOI] Chen, X., B. Cousins, M. McEllistrem, and R. J. Hamers. HIGH-PERFORMANCE, LOW-NOISE DIGITAL CONTROLLER FOR INCHWORM PIEZOELECTRIC TRANSLATORS. Review of Scientific Instruments 1992, 63, 4308-4313.
    [Bibtex]
    @Article{Hamers241,
    Title = {HIGH-PERFORMANCE, LOW-NOISE DIGITAL CONTROLLER FOR INCHWORM PIEZOELECTRIC TRANSLATORS},
    Author = {Chen, X. and Cousins, B. and McEllistrem, M. and Hamers, R. J.},
    Journal = {Review of Scientific Instruments},
    Year = {1992},
    Note = {Chen, x cousins, b mcellistrem, m hamers, rj
    Part 1},
    Number = {10},
    Pages = {4308-4313},
    Volume = {63},
    Abstract = {We have designed and constructed a high-performance, low-noise digital controller for "inchworm" piezoelectric translators. The controller features a maximum output voltage of 700 V, an rms noise level of less than 2 mV, and is capable of driving inchworms at speeds of up to 0.23 mm/s. The controller offers substantially better performance in terms of resolution, noise, speed, and cost than commercial controllers, and is suitable for atomic resolution scanning tunneling microscopy and atomic force microscopy applications.},
    Doi = {10.1063/1.1143729},
    ISSN = {0034-6748},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1992JV13200008
    http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=RSINAK000063000010004308000001&idtype=cvips&doi=10.1063/1.1143729&prog=normal}
    }
  • Hamers, R. J.. 1992. Scanning tunneling microscopy on semiconductors. Edited by Wiesendanger, R.. In Scanning Tunneling Microscopy, Springer-Verlag. .
    [Bibtex]
    @InBook{Hamers518,
    Title = {Scanning tunneling microscopy on semiconductors},
    Author = {Hamers, R. J.},
    Editor = {Wiesendanger, R.},
    Publisher = {Springer-Verlag},
    Year = {1992},
    Type = {Book Section},
    Booktitle = {Scanning Tunneling Microscopy}
    }
  • Hamers, R. J.. 1992. Scanning Tunneling Microscopy of Metals on Semiconductors. Edited by Wolf, D. and S. Yip. In Materials Interfaces: Atomic-level Structure and Properties, Chapman & Hall. .
    [Bibtex]
    @InBook{Hamers528,
    Title = {Scanning Tunneling Microscopy of Metals on Semiconductors},
    Author = {Hamers, R. J.},
    Editor = {Wolf, D. and Yip, S.},
    Publisher = {Chapman \& Hall},
    Year = {1992},
    Type = {Book Section},
    Booktitle = {Materials Interfaces: Atomic-level Structure and Properties}
    }

1991

  • [DOI] Cahill, D. G. and R. J. Hamers. SURFACE PHOTOVOLTAGE OF AG ON SI(111)-7X7 BY SCANNING TUNNELING MICROSCOPY. Physical Review B 1991, 44, 1387-1390.
    [Bibtex]
    @Article{Hamers246,
    Title = {SURFACE PHOTOVOLTAGE OF AG ON SI(111)-7X7 BY SCANNING TUNNELING MICROSCOPY},
    Author = {Cahill, D. G. and Hamers, R. J.},
    Journal = {Physical Review B},
    Year = {1991},
    Note = {Cahill, dg hamers, rj},
    Number = {3},
    Pages = {1387-1390},
    Volume = {44},
    Abstract = {Using a scanning tunneling microscope and light from a He-Ne laser, we have measured the surface photovoltage of the Si(111)-7 x 7 surface with coverages of Ag up to 1 monolayer. The data agree with a model for the photovoltage based on the recombination of photoexcited minority carriers with majority carriers thermally excited over the surface Schottky barrier. The surface Fermi-level positions derived from these data are consistent for n- and p-type Si decreasing from 0.60 eV above the valence-band maximum for the dean surface to 0.40 eV near 1 monolayer coverage. Although our photovoltage data are spatially resolved on an atomic scale, we have not observed any spatial variation in the photovoltage on the clean surface or on surfaces partially covered by Ag islands. This can be understood on the basis of the finite surface conductivity of the Si(111)-7 x 7 reconstruction.},
    Doi = {10.1103/PhysRevB.44.1387},
    ISSN = {0163-1829},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1991FW10500063
    http://prb.aps.org/abstract/PRB/v44/i3/p1387_1}
    }
  • [DOI] Chen, C. J. and R. J. Hamers. ROLE OF ATOMIC FORCE IN TUNNELING-BARRIER MEASUREMENTS. Journal of Vacuum Science & Technology B 1991, 9, 503-505.
    [Bibtex]
    @Article{Hamers247,
    Title = {ROLE OF ATOMIC FORCE IN TUNNELING-BARRIER MEASUREMENTS},
    Author = {Chen, C. J. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology B},
    Year = {1991},
    Note = {Chen, cj hamers, rj
    5th international conf on scanning tunneling microscopy/spectroscopy ( stm 90 ) / 1st international conf on nanometer scale science and technology ( nano 1 )
    Jul 23-27, 1990
    Baltimore, md
    Amer vacuum soc, usn, off naval res, usaf, off sci res, natl sci fdn, john hopkins univ, appl phys lab
    Part 2},
    Number = {2},
    Pages = {503-505},
    Volume = {9},
    Abstract = {Experimental measurements of the apparent barrier height as a function of tip-sample separation using a scanning tunneling microscope (with clean W tips and clean Si surfaces in ultra high-vacuum) show that the barrier height starts at 3.5 eV at large separations, increases to 4.8 eV at about 1.5 angstrom before the mechanical contact, and then drops to below 0.3 eV within a fraction of an angstrom. At the distances encountered in scanning tunneling microscopy, forces between sample and tip can be significant. Using a simple model of this system including tip-sample forces leads to a calculated apparent barrier height which quantitatively reproduces the observed variation in apparent barrier height over the entire range of tip-sample separations.},
    Doi = {10.1116/1.585556},
    ISSN = {1071-1023},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1991FL00400020
    http://avspublications.org/jvstb/resource/1/jvtbd9/v9/i2/p503_s1
    http://avspublications.org/jvstb/resource/1/jvtbd9/v9/i2/p503_s1?isAuthorized=no}
    }
  • [DOI] Hamers, R. J. and D. G. Cahill. ULTRAFAST TIME RESOLUTION IN SCANNED PROBE MICROSCOPES – SURFACE PHOTOVOLTAGE ON SI(111)-(7X7). Journal of Vacuum Science & Technology B 1991, 9, 514-518.
    [Bibtex]
    @Article{Hamers248,
    Title = {ULTRAFAST TIME RESOLUTION IN SCANNED PROBE MICROSCOPES - SURFACE PHOTOVOLTAGE ON SI(111)-(7X7)},
    Author = {Hamers, R. J. and Cahill, D. G.},
    Journal = {Journal of Vacuum Science \& Technology B},
    Year = {1991},
    Note = {Hamers, rj cahill, dg
    5th international conf on scanning tunneling microscopy/spectroscopy ( stm 90 ) / 1st international conf on nanometer scale science and technology ( nano 1 )
    Jul 23-27, 1990
    Baltimore, md
    Amer vacuum soc, usn, off naval res, usaf, off sci res, natl sci fdn, john hopkins univ, appl phys lab
    Part 2},
    Number = {2},
    Pages = {514-518},
    Volume = {9},
    Abstract = {The speed limitations conventionally encountered in scanning tunneling microscopy, scanning capacitance microscopy, and atomic force microscopy result from the external electronics and are not inherent to the techniques themselves. Ultrafast time resolution can be achieved through the use of correlation methods. We demonstrate the application of time-resolved optical correlation techniques to scanned probe microscopy by probing the relaxation of photo-excited carriers at the Si(111)-(7 x 7) surface on the nanosecond and picosecond time scales using scanning tunneling and scanning capacitance microscopy measurements of the surface photovoltage. The observed temporal response demonstrates that the voltage arises from photovoltaic effects and does not arise from direct optical rectification in the tunnel junction gap.},
    Doi = {10.1116/1.585559},
    ISSN = {1071-1023},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1991FL00400023
    http://avspublications.org/jvstb/resource/1/jvtbd9/v9/i2/p514_s1
    http://avspublications.org/jvstb/resource/1/jvtbd9/v9/i2/p514_s1?isAuthorized=no}
    }
  • [DOI] Cahill, D. G. and R. J. Hamers. SCANNING TUNNELING MICROSCOPY OF PHOTOEXCITED CARRIERS AT THE SI(001) SURFACE. Journal of Vacuum Science & Technology B 1991, 9, 564-567.
    [Bibtex]
    @Article{Hamers249,
    Title = {SCANNING TUNNELING MICROSCOPY OF PHOTOEXCITED CARRIERS AT THE SI(001) SURFACE},
    Author = {Cahill, D. G. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology B},
    Year = {1991},
    Note = {Cahill, dg hamers, rj
    5th international conf on scanning tunneling microscopy/spectroscopy ( stm 90 ) / 1st international conf on nanometer scale science and technology ( nano 1 )
    Jul 23-27, 1990
    Baltimore, md
    Amer vacuum soc, usn, off naval res, usaf, off sci res, natl sci fdn, john hopkins univ, appl phys lab
    Part 2},
    Number = {2},
    Pages = {564-567},
    Volume = {9},
    Abstract = {A scanning tunneling microscope is used to probe changes in the surface potential created by photoexcited carriers. At small tunneling currents, the dependence of surface photovoltage on laser intensity agrees with a model based on the transport of majority carriers through the depletion layer. At larger values of the tunneling current, charging of the surface by the current modifies the surface photovoltage because of changes in band bending near the probe tip. Spatial variations in the surface photovoltage are observed on a length scale comparable to the width of the depletion layer. Variations on an atomic scale are also observed and are interpreted as an increase in surface charging at specific defects on the Si(001) surface.},
    Doi = {10.1116/1.585569},
    ISSN = {1071-1023},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1991FL00400033
    http://avspublications.org/jvstb/resource/1/jvtbd9/v9/i2/p564_s1
    http://avspublications.org/jvstb/resource/1/jvtbd9/v9/i2/p564_s1?isAuthorized=no}
    }
  • Hamers, R. J.. ATOMIC-SCALE IMAGING WITH THE SCANNING TUNNELING MICROSCOPE. MRS Bulletin 1991, 16, 22-26.
    [Bibtex]
    @Article{Hamers250,
    Title = {ATOMIC-SCALE IMAGING WITH THE SCANNING TUNNELING MICROSCOPE},
    Author = {Hamers, R. J.},
    Journal = {MRS Bulletin},
    Year = {1991},
    Note = {Hamers, rj},
    Number = {3},
    Pages = {22-26},
    Volume = {16},
    ISSN = {0883-7694},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1991FD77800004}
    }
  • [DOI] Alerhand, O. L., A. N. Berker, J. D. Joannopoulos, D. Vanderbilt, R. J. Hamers, and J. E. Demuth. 1ST-ORDER TRANSITIONS BETWEEN SURFACE PHASES WITH DIFFERENT STEP STRUCTURES – REPLY. Physical Review Letters 1991, 66, 962-962.
    [Bibtex]
    @Article{Hamers251,
    Title = {1ST-ORDER TRANSITIONS BETWEEN SURFACE PHASES WITH DIFFERENT STEP STRUCTURES - REPLY},
    Author = {Alerhand, O. L. and Berker, A. N. and Joannopoulos, J. D. and Vanderbilt, D. and Hamers, R. J. and Demuth, J. E.},
    Journal = {Physical Review Letters},
    Year = {1991},
    Note = {Alerhand, ol berker, an joannopoulos, jd vanderbilt, d hamers, rj demuth, je},
    Number = {7},
    Pages = {962-962},
    Volume = {66},
    Doi = {10.1103/PhysRevLett.66.962},
    ISSN = {0031-9007},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1991EX57800035
    http://prl.aps.org/abstract/PRL/v66/i7/p962_1}
    }
  • Hamers, R. J.. 1991. Scanning Tunneling Microscopy. In Encyclopedia of Physics, VCH Publishers. .
    [Bibtex]
    @InBook{Hamers517,
    Title = {Scanning Tunneling Microscopy},
    Author = {Hamers, R. J.},
    Publisher = {VCH Publishers},
    Year = {1991},
    Type = {Book Section},
    Booktitle = {Encyclopedia of Physics}
    }

1990

  • [DOI] Hamers, R. J. and D. G. Cahill. ULTRAFAST TIME RESOLUTION IN SCANNED PROBE MICROSCOPIES. Applied Physics Letters 1990, 57, 2031-2033.
    [Bibtex]
    @Article{Hamers252,
    Title = {ULTRAFAST TIME RESOLUTION IN SCANNED PROBE MICROSCOPIES},
    Author = {Hamers, R. J. and Cahill, D. G.},
    Journal = {Applied Physics Letters},
    Year = {1990},
    Note = {Hamers, rj cahill, dg},
    Number = {19},
    Pages = {2031-2033},
    Volume = {57},
    Doi = {10.1063/1.103997},
    ISSN = {0003-6951},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1990EG58700029
    http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=APPLAB000057000019002031000001&idtype=cvips&doi=10.1063/1.103997&prog=normal}
    }
  • [DOI] Hamers, R. J. and K. Markert. SURFACE PHOTOVOLTAGE ON SI(111)-(7X7) PROBED BY OPTICALLY PUMPED SCANNING TUNNELING MICROSCOPY. Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films 1990, 8, 3524-3530.
    [Bibtex]
    @Article{Hamers253,
    Title = {SURFACE PHOTOVOLTAGE ON SI(111)-(7X7) PROBED BY OPTICALLY PUMPED SCANNING TUNNELING MICROSCOPY},
    Author = {Hamers, R. J. and Markert, K.},
    Journal = {Journal of Vacuum Science \& Technology a-Vacuum Surfaces and Films},
    Year = {1990},
    Note = {Hamers, rj markert, k},
    Number = {4},
    Pages = {3524-3530},
    Volume = {8},
    Doi = {10.1116/1.576501},
    ISSN = {0734-2101},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1990DP52000086
    http://avspublications.org/jvsta/resource/1/jvtad6/v8/i4/p3524_s1
    http://avspublications.org/jvsta/resource/1/jvtad6/v8/i4/p3524_s1?isAuthorized=no}
    }
  • [DOI] Alerhand, O. L., A. N. Berker, J. D. Joannopoulos, D. Vanderbilt, R. J. Hamers, and J. E. Demuth. FINITE-TEMPERATURE PHASE-DIAGRAM OF VICINAL SI(100) SURFACES. Physical Review Letters 1990, 64, 2406-2409.
    [Bibtex]
    @Article{Hamers254,
    Title = {FINITE-TEMPERATURE PHASE-DIAGRAM OF VICINAL SI(100) SURFACES},
    Author = {Alerhand, O. L. and Berker, A. N. and Joannopoulos, J. D. and Vanderbilt, D. and Hamers, R. J. and Demuth, J. E.},
    Journal = {Physical Review Letters},
    Year = {1990},
    Note = {Alerhand, ol berker, an joannopoulos, jd vanderbilt, d hamers, rj demuth, je},
    Number = {20},
    Pages = {2406-2409},
    Volume = {64},
    Doi = {10.1103/PhysRevLett.64.2406},
    ISSN = {0031-9007},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1990DC93700018
    http://prl.aps.org/abstract/PRL/v64/i20/p2406_1}
    }
  • [DOI] Hamers, R. J. and K. Markert. ATOMICALLY RESOLVED CARRIER RECOMBINATION AT SI(111)-(7X7) SURFACES. Physical Review Letters 1990, 64, 1051-1054.
    [Bibtex]
    @Article{Hamers255,
    Title = {ATOMICALLY RESOLVED CARRIER RECOMBINATION AT SI(111)-(7X7) SURFACES},
    Author = {Hamers, R. J. and Markert, K.},
    Journal = {Physical Review Letters},
    Year = {1990},
    Note = {Hamers, rj markert, k},
    Number = {9},
    Pages = {1051-1054},
    Volume = {64},
    Doi = {10.1103/PhysRevLett.64.1051},
    ISSN = {0031-9007},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1990CQ14100018
    http://prl.aps.org/abstract/PRL/v64/i9/p1051_1}
    }
  • [DOI] Hamers, R. J., U. K. Kohler, and J. E. Demuth. EPITAXIAL-GROWTH OF SILICON ON SI(001) BY SCANNING TUNNELING MICROSCOPY. Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films 1990, 8, 195-200.
    [Bibtex]
    @Article{Hamers256,
    Title = {EPITAXIAL-GROWTH OF SILICON ON SI(001) BY SCANNING TUNNELING MICROSCOPY},
    Author = {Hamers, R. J. and Kohler, U. K. and Demuth, J. E.},
    Journal = {Journal of Vacuum Science \& Technology a-Vacuum Surfaces and Films},
    Year = {1990},
    Note = {Hamers, rj kohler, uk demuth, je
    4th international conf on scanning tunneling microscopy/spectroscopy
    Jul 09-14, 1989
    Oarai, japan
    Japan soc appl phys, amer vacuum soc, commorat assoc japan world exposit, japan iron \& steel federat, hitachi},
    Number = {1},
    Pages = {195-200},
    Volume = {8},
    Doi = {10.1116/1.577063},
    ISSN = {0734-2101},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1990CL59400038
    http://avspublications.org/jvsta/resource/1/jvtad6/v8/i1/p195_s1
    http://avspublications.org/jvsta/resource/1/jvtad6/v8/i1/p195_s1?isAuthorized=no}
    }
  • [DOI] Demuth, J. E., U. Koehler, and R. J. Hamers. SURFACE DIFFRACTOMETRY AND LATTICE IMAGING OF SCANNING TUNNELING MICROSCOPY IMAGES. Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films 1990, 8, 214-217.
    [Bibtex]
    @Article{Hamers257,
    Title = {SURFACE DIFFRACTOMETRY AND LATTICE IMAGING OF SCANNING TUNNELING MICROSCOPY IMAGES},
    Author = {Demuth, J. E. and Koehler, U. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology a-Vacuum Surfaces and Films},
    Year = {1990},
    Note = {Demuth, je koehler, u hamers, rj
    4th international conf on scanning tunneling microscopy/spectroscopy
    Jul 09-14, 1989
    Oarai, japan
    Japan soc appl phys, amer vacuum soc, commorat assoc japan world exposit, japan iron \& steel federat, hitachi},
    Number = {1},
    Pages = {214-217},
    Volume = {8},
    Doi = {10.1116/1.577069},
    ISSN = {0734-2101},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1990CL59400042
    http://avspublications.org/jvsta/resource/1/jvtad6/v8/i1/p214_s1
    http://avspublications.org/jvsta/resource/1/jvtad6/v8/i1/p214_s1?isAuthorized=no}
    }
  • [DOI] Hashizume, T., R. J. Hamers, J. E. Demuth, K. Markert, and T. Sakurai. INITIAL-STAGE DEPOSITION OF AG ON THE SI(100)2X1 SURFACE STUDIED BY SCANNING TUNNELING MICROSCOPY. Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films 1990, 8, 249-250.
    [Bibtex]
    @Article{Hamers258,
    Title = {INITIAL-STAGE DEPOSITION OF AG ON THE SI(100)2X1 SURFACE STUDIED BY SCANNING TUNNELING MICROSCOPY},
    Author = {Hashizume, T. and Hamers, R. J. and Demuth, J. E. and Markert, K. and Sakurai, T.},
    Journal = {Journal of Vacuum Science \& Technology a-Vacuum Surfaces and Films},
    Year = {1990},
    Note = {Hashizume, t hamers, rj demuth, je markert, k sakurai, t
    4th international conf on scanning tunneling microscopy/spectroscopy
    Jul 09-14, 1989
    Oarai, japan
    Japan soc appl phys, amer vacuum soc, commorat assoc japan world exposit, japan iron \& steel federat, hitachi},
    Number = {1},
    Pages = {249-250},
    Volume = {8},
    Doi = {10.1116/1.577077},
    ISSN = {0734-2101},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1990CL59400050
    http://avspublications.org/jvsta/resource/1/jvtad6/v8/i1/p249_s1
    http://avspublications.org/jvsta/resource/1/jvtad6/v8/i1/p249_s1?isAuthorized=no}
    }
  • [DOI] Frenken, J. W. M., R. J. Hamers, and J. E. Demuth. THERMAL ROUGHENING STUDIED BY SCANNING TUNNELING MICROSCOPY. Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films 1990, 8, 293-296.
    [Bibtex]
    @Article{Hamers259,
    Title = {THERMAL ROUGHENING STUDIED BY SCANNING TUNNELING MICROSCOPY},
    Author = {Frenken, J. W. M. and Hamers, R. J. and Demuth, J. E.},
    Journal = {Journal of Vacuum Science \& Technology a-Vacuum Surfaces and Films},
    Year = {1990},
    Note = {Frenken, jwm hamers, rj demuth, je
    4th international conf on scanning tunneling microscopy/spectroscopy
    Jul 09-14, 1989
    Oarai, japan
    Japan soc appl phys, amer vacuum soc, commorat assoc japan world exposit, japan iron \& steel federat, hitachi},
    Number = {1},
    Pages = {293-296},
    Volume = {8},
    Doi = {10.1116/1.577088},
    ISSN = {0734-2101},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1990CL59400061
    http://avspublications.org/jvsta/resource/1/jvtad6/v8/i1/p293_s1
    http://avspublications.org/jvsta/resource/1/jvtad6/v8/i1/p293_s1?isAuthorized=no}
    }

1989

  • [DOI] Hamers, R. J., U. K. Kohler, and J. E. Demuth. NUCLEATION AND GROWTH OF EPITAXIAL SILICON ON SI(001) AND SI(111) SURFACES BY SCANNING TUNNELING MICROSCOPY. Ultramicroscopy 1989, 31, 10-19.
    [Bibtex]
    @Article{Hamers260,
    Title = {NUCLEATION AND GROWTH OF EPITAXIAL SILICON ON SI(001) AND SI(111) SURFACES BY SCANNING TUNNELING MICROSCOPY},
    Author = {Hamers, R. J. and Kohler, U. K. and Demuth, J. E.},
    Journal = {Ultramicroscopy},
    Year = {1989},
    Note = {Hamers, rj kohler, uk demuth, je},
    Number = {1},
    Pages = {10-19},
    Volume = {31},
    Doi = {10.1016/0304-3991(89)90029-6},
    ISSN = {0304-3991},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1989AQ74300003
    http://www.sciencedirect.com/science/article/pii/0304399189900296}
    }
  • [DOI] Hamers, R. J.. EFFECTS OF COVERAGE ON THE GEOMETRY AND ELECTRONIC-STRUCTURE OF AL OVERLAYERS ON SI(111). Physical Review B 1989, 40, 1657-1671.
    [Bibtex]
    @Article{Hamers261,
    Title = {EFFECTS OF COVERAGE ON THE GEOMETRY AND ELECTRONIC-STRUCTURE OF AL OVERLAYERS ON SI(111)},
    Author = {Hamers, R. J.},
    Journal = {Physical Review B},
    Year = {1989},
    Note = {Hamers, rj},
    Number = {3},
    Pages = {1657-1671},
    Volume = {40},
    Doi = {10.1103/PhysRevB.40.1657},
    ISSN = {0163-1829},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1989AG98100028
    http://prb.aps.org/abstract/PRB/v40/i3/p1657_1}
    }
  • [DOI] Hamers, R. J. and U. K. Kohler. DETERMINATION OF THE LOCAL ELECTRONIC-STRUCTURE OF ATOMIC-SIZED DEFECTS ON SI(001) BY TUNNELING SPECTROSCOPY. Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films 1989, 7, 2854-2859.
    [Bibtex]
    @Article{Hamers262,
    Title = {DETERMINATION OF THE LOCAL ELECTRONIC-STRUCTURE OF ATOMIC-SIZED DEFECTS ON SI(001) BY TUNNELING SPECTROSCOPY},
    Author = {Hamers, R. J. and Kohler, U. K.},
    Journal = {Journal of Vacuum Science \& Technology a-Vacuum Surfaces and Films},
    Year = {1989},
    Note = {Hamers, rj kohler, uk},
    Number = {4},
    Pages = {2854-2859},
    Volume = {7},
    Doi = {10.1116/1.576158},
    ISSN = {0734-2101},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1989AG67700062
    http://avspublications.org/jvsta/resource/1/jvtad6/v7/i4/p2854_s1
    http://avspublications.org/jvsta/resource/1/jvtad6/v7/i4/p2854_s1?isAuthorized=no}
    }
  • Kohler, U., J. E. Demuth, and R. J. Hamers. SCANNING TUNNELING MICROSCOPY STUDY OF LOW-TEMPERATURE EPITAXIAL-GROWTH OF SILICON ON SI(111)-(7X7). Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films 1989, 7, 2860-2867.
    [Bibtex]
    @Article{Hamers263,
    Title = {SCANNING TUNNELING MICROSCOPY STUDY OF LOW-TEMPERATURE EPITAXIAL-GROWTH OF SILICON ON SI(111)-(7X7)},
    Author = {Kohler, U. and Demuth, J. E. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology a-Vacuum Surfaces and Films},
    Year = {1989},
    Note = {Kohler, u demuth, je hamers, rj},
    Number = {4},
    Pages = {2860-2867},
    Volume = {7},
    ISSN = {0734-2101},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1989AG67700063
    http://avspublications.org/jvsta/resource/1/jvtad6/v7/i4/p2860_s1}
    }
  • [DOI] Manassen, Y., R. J. Hamers, J. E. Demuth, and A. J. Castellano. DIRECT OBSERVATION OF THE PRECESSION OF INDIVIDUAL PARAMAGNETIC SPINS ON OXIDIZED SILICON SURFACES. Physical Review Letters 1989, 62, 2531-2534.
    [Bibtex]
    @Article{Hamers264,
    Title = {DIRECT OBSERVATION OF THE PRECESSION OF INDIVIDUAL PARAMAGNETIC SPINS ON OXIDIZED SILICON SURFACES},
    Author = {Manassen, Y. and Hamers, R. J. and Demuth, J. E. and Castellano, A. J.},
    Journal = {Physical Review Letters},
    Year = {1989},
    Note = {Manassen, y hamers, rj demuth, je castellano, aj},
    Number = {21},
    Pages = {2531-2534},
    Volume = {62},
    Doi = {10.1103/PhysRevLett.62.2531},
    ISSN = {0031-9007},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1989U666900028
    http://prl.aps.org/abstract/PRL/v62/i21/p2531_1}
    }
  • [DOI] Demuth, J. E., U. K. Koehler, R. J. Hamers, and P. Kaplan. PHASE-SEPARATION ON AN ATOMIC SCALE – THE FORMATION OF A NOVEL QUASIPERIODIC 2D-STRUCTURE. Physical Review Letters 1989, 62, 641-644.
    [Bibtex]
    @Article{Hamers266,
    Title = {PHASE-SEPARATION ON AN ATOMIC SCALE - THE FORMATION OF A NOVEL QUASIPERIODIC 2D-STRUCTURE},
    Author = {Demuth, J. E. and Koehler, U. K. and Hamers, R. J. and Kaplan, P.},
    Journal = {Physical Review Letters},
    Year = {1989},
    Note = {Demuth, je koehler, uk hamers, rj kaplan, p},
    Number = {6},
    Pages = {641-644},
    Volume = {62},
    Doi = {10.1103/PhysRevLett.62.641},
    ISSN = {0031-9007},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1989T105500009
    http://prl.aps.org/abstract/PRL/v62/i6/p641_1}
    }
  • [DOI] Hamers, R. J.. ATOMIC-RESOLUTION SURFACE SPECTROSCOPY WITH THE SCANNING TUNNELING MICROSCOPE. Annual Review of Physical Chemistry 1989, 40, 531-559.
    [Bibtex]
    @Article{Hamers267,
    Title = {ATOMIC-RESOLUTION SURFACE SPECTROSCOPY WITH THE SCANNING TUNNELING MICROSCOPE},
    Author = {Hamers, R. J.},
    Journal = {Annual Review of Physical Chemistry},
    Year = {1989},
    Note = {Hamers, rj},
    Pages = {531-559},
    Volume = {40},
    Doi = {10.1146/annurev.physchem.40.1.531},
    ISSN = {0066-426X},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1989AY22000019}
    }
  • Hamers, R. J.. 1989. Scanning tunneling microscopy. Edited by Chiarotti, G.. In Physics of Solid Surfaces, Landolt-Bornstein. .
    [Bibtex]
    @InBook{Hamers514,
    Title = {Scanning tunneling microscopy},
    Author = {Hamers, R. J.},
    Editor = {Chiarotti, G.},
    Publisher = {Landolt-Bornstein},
    Year = {1989},
    Type = {Book Section},
    Booktitle = {Physics of Solid Surfaces}
    }
  • Hamers, R. J. and R. H. Koch. 1989. Scanning tunneling microscopy and spectrosocpy of Si dangling bond defects. Edited by Helms, C. R.. In Physical and chemistry of SiO<sub>2</sub> and the Si-SiO<sub>2</sub> Interface, Plenum Press. .
    [Bibtex]
    @InBook{Hamers515,
    Title = {Scanning tunneling microscopy and spectrosocpy of Si dangling bond defects},
    Author = {Hamers, R. J. and Koch, R. H.},
    Editor = {Helms, C. R.},
    Publisher = {Plenum Press},
    Year = {1989},
    Type = {Book Section},
    Booktitle = {Physical and chemistry of SiO<sub>2</sub> and the Si-SiO<sub>2</sub> Interface}
    }
  • Hamers, R. J. and J. j>. Wynne. Time-resolved Tunneling Microscope. IBM Technical Disclosure Bulletin 1989, 31, 350.
    [Bibtex]
    @Article{Hamers516,
    Title = {Time-resolved Tunneling Microscope},
    Author = {Hamers, R. J. and Wynne, J.j>},
    Journal = {IBM Technical Disclosure Bulletin},
    Year = {1989},
    Pages = {350},
    Volume = {31},
    Type = {Journal Article}
    }

1988

  • Demuth, J. E., U. Koehler, and R. J. Hamers. THE STM LEARNING-CURVE AND WHERE IT MAY TAKE US. Journal of Microscopy-Oxford 1988, 152, 299-316.
    [Bibtex]
    @Article{Hamers268,
    Title = {THE STM LEARNING-CURVE AND WHERE IT MAY TAKE US},
    Author = {Demuth, J. E. and Koehler, U. and Hamers, R. J.},
    Journal = {Journal of Microscopy-Oxford},
    Year = {1988},
    Note = {Demuth, je koehler, u hamers, rj
    Part 2},
    Pages = {299-316},
    Volume = {152},
    ISSN = {0022-2720},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1988U546700001}
    }
  • [DOI] Hamers, R. J.. CHARACTERIZATION OF LOCALIZED ATOMIC SURFACE-DEFECTS BY TUNNELING MICROSCOPY AND SPECTROSCOPY. Journal of Vacuum Science & Technology B 1988, 6, 1462-1467.
    [Bibtex]
    @Article{Hamers270,
    Title = {CHARACTERIZATION OF LOCALIZED ATOMIC SURFACE-DEFECTS BY TUNNELING MICROSCOPY AND SPECTROSCOPY},
    Author = {Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology B},
    Year = {1988},
    Note = {Hamers, rj},
    Number = {4},
    Pages = {1462-1467},
    Volume = {6},
    Doi = {10.1116/1.584241},
    ISSN = {1071-1023},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1988P729100076
    http://avspublications.org/jvstb/resource/1/jvtbd9/v6/i4/p1462_s1
    http://avspublications.org/jvstb/resource/1/jvtbd9/v6/i4/p1462_s1?isAuthorized=no}
    }
  • [DOI] Kohler, U. K., J. E. Demuth, and R. J. Hamers. SURFACE RECONSTRUCTION AND THE NUCLEATION OF PALLADIUM SILICIDE ON SI(111). Physical Review Letters 1988, 60, 2499-2502.
    [Bibtex]
    @Article{Hamers271,
    Title = {SURFACE RECONSTRUCTION AND THE NUCLEATION OF PALLADIUM SILICIDE ON SI(111)},
    Author = {Kohler, U. K. and Demuth, J. E. and Hamers, R. J.},
    Journal = {Physical Review Letters},
    Year = {1988},
    Note = {Kohler, uk demuth, je hamers, rj},
    Number = {24},
    Pages = {2499-2502},
    Volume = {60},
    Doi = {10.1103/PhysRevLett.60.2499},
    ISSN = {0031-9007},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1988N799600015
    http://prl.aps.org/abstract/PRL/v60/i24/p2499_1}
    }
  • [DOI] Hamers, R. J. and J. E. Demuth. ELECTRONIC-STRUCTURE OF LOCALIZED SI DANGLING-BOND DEFECTS BY TUNNELING SPECTROSCOPY. Physical Review Letters 1988, 60, 2527-2530.
    [Bibtex]
    @Article{Hamers272,
    Title = {ELECTRONIC-STRUCTURE OF LOCALIZED SI DANGLING-BOND DEFECTS BY TUNNELING SPECTROSCOPY},
    Author = {Hamers, R. J. and Demuth, J. E.},
    Journal = {Physical Review Letters},
    Year = {1988},
    Note = {Hamers, rj demuth, je},
    Number = {24},
    Pages = {2527-2530},
    Volume = {60},
    Doi = {10.1103/PhysRevLett.60.2527},
    ISSN = {0031-9007},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1988N799600022
    http://prl.aps.org/abstract/PRL/v60/i24/p2527_1}
    }
  • [DOI] Hamers, R. J., P. L. Houston, and R. P. Merrill. COMPETITION BETWEEN DIRECT-INELASTIC AND TRAPPING DESORPTION CHANNELS IN THE SCATTERING OF NO (V=O,J) FROM IR(111). Journal of Chemical Physics 1988, 88, 6548-6555.
    [Bibtex]
    @Article{Hamers274,
    Title = {COMPETITION BETWEEN DIRECT-INELASTIC AND TRAPPING DESORPTION CHANNELS IN THE SCATTERING OF NO (V=O,J) FROM IR(111)},
    Author = {Hamers, R. J. and Houston, P. L. and Merrill, R. P.},
    Journal = {Journal of Chemical Physics},
    Year = {1988},
    Note = {Hamers, rj houston, pl merrill, rp},
    Number = {10},
    Pages = {6548-6555},
    Volume = {88},
    Doi = {10.1063/1.454441},
    ISSN = {0021-9606},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1988N555800057
    http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JCPSA6000088000010006548000001&idtype=cvips&doi=10.1063/1.454441&prog=normal}
    }
  • Hamers, R. J., R. H. Koch, and J. E. Demuth. SCANNING TUNNELING MICROSCOPY – AN ATOMIC-SCALE PROBE OF SURFACE GEOMETRY AND ELECTRONIC-STRUCTURE. Journal of the Electrochemical Society 1988, 135, C136-C136.
    [Bibtex]
    @Article{Hamers275,
    Title = {SCANNING TUNNELING MICROSCOPY - AN ATOMIC-SCALE PROBE OF SURFACE GEOMETRY AND ELECTRONIC-STRUCTURE},
    Author = {Hamers, R. J. and Koch, R. H. and Demuth, J. E.},
    Journal = {Journal of the Electrochemical Society},
    Year = {1988},
    Note = {Hamers, rj koch, rh demuth, je},
    Number = {3},
    Pages = {C136-C136},
    Volume = {135},
    ISSN = {0013-4651},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1988M543700286}
    }
  • [DOI] Hamers, R. J., P. Avouris, and F. Bozso. A SCANNING TUNNELING MICROSCOPY STUDY OF THE REACTION OF SI(001)-(2X1) WITH NH3. Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films 1988, 6, 508-511.
    [Bibtex]
    @Article{Hamers276,
    Title = {A SCANNING TUNNELING MICROSCOPY STUDY OF THE REACTION OF SI(001)-(2X1) WITH NH3},
    Author = {Hamers, R. J. and Avouris, P. and Bozso, F.},
    Journal = {Journal of Vacuum Science \& Technology a-Vacuum Surfaces and Films},
    Year = {1988},
    Note = {Hamers, rj avouris, p bozso, f},
    Number = {2},
    Pages = {508-511},
    Volume = {6},
    Doi = {10.1116/1.575369},
    ISSN = {0734-2101},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1988M650200079
    http://avspublications.org/jvsta/resource/1/jvtad6/v6/i2/p508_s1
    http://avspublications.org/jvsta/resource/1/jvtad6/v6/i2/p508_s1?isAuthorized=no}
    }
  • [DOI] Hamers, R. J. and J. E. Demuth. ATOMIC-STRUCTURE AND BONDING OF SI(111)-(SQUARE-ROOT-3XSQUARE-ROOT-3)AL. Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films 1988, 6, 512-516.
    [Bibtex]
    @Article{Hamers277,
    Title = {ATOMIC-STRUCTURE AND BONDING OF SI(111)-(SQUARE-ROOT-3XSQUARE-ROOT-3)AL},
    Author = {Hamers, R. J. and Demuth, J. E.},
    Journal = {Journal of Vacuum Science \& Technology a-Vacuum Surfaces and Films},
    Year = {1988},
    Note = {Hamers, rj demuth, je},
    Number = {2},
    Pages = {512-516},
    Volume = {6},
    Doi = {10.1116/1.575370},
    ISSN = {0734-2101},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1988M650200080
    http://avspublications.org/jvsta/resource/1/jvtad6/v6/i2/p512_s1
    http://avspublications.org/jvsta/resource/1/jvtad6/v6/i2/p512_s1?isAuthorized=no}
    }
  • [DOI] Schneir, J., R. Sonnenfeld, O. Marti, P. K. Hansma, J. E. Demuth, and R. J. Hamers. TUNNELING MICROSCOPY, LITHOGRAPHY, AND SURFACE-DIFFUSION ON AN EASILY PREPARED, ATOMICALLY FLAT GOLD SURFACE. Journal of Applied Physics 1988, 63, 717-721.
    [Bibtex]
    @Article{Hamers278,
    Title = {TUNNELING MICROSCOPY, LITHOGRAPHY, AND SURFACE-DIFFUSION ON AN EASILY PREPARED, ATOMICALLY FLAT GOLD SURFACE},
    Author = {Schneir, J. and Sonnenfeld, R. and Marti, O. and Hansma, P. K. and Demuth, J. E. and Hamers, R. J.},
    Journal = {Journal of Applied Physics},
    Year = {1988},
    Note = {Schneir, j sonnenfeld, r marti, o hansma, pk demuth, je hamers, rj},
    Number = {3},
    Pages = {717-721},
    Volume = {63},
    Doi = {10.1063/1.340062},
    ISSN = {0021-8979},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1988L836200017
    http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JAPIAU000063000003000717000001&idtype=cvips&doi=10.1063/1.340062&prog=normal}
    }
  • [DOI] Demuth, J. E., E. J. Vonlenen, R. M. Tromp, and R. J. Hamers. LOCAL ELECTRONIC-STRUCTURE AND SURFACE GEOMETRY OF AG ON SI(111). Journal of Vacuum Science & Technology B 1988, 6, 18-26.
    [Bibtex]
    @Article{Hamers279,
    Title = {LOCAL ELECTRONIC-STRUCTURE AND SURFACE GEOMETRY OF AG ON SI(111)},
    Author = {Demuth, J. E. and Vonlenen, E. J. and Tromp, R. M. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology B},
    Year = {1988},
    Note = {Demuth, je vonlenen, ej tromp, rm hamers, rj},
    Number = {1},
    Pages = {18-26},
    Volume = {6},
    Doi = {10.1116/1.584042},
    ISSN = {1071-1023},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1988M172300002
    http://avspublications.org/jvstb/resource/1/jvtbd9/v6/i1/p18_s1
    http://avspublications.org/jvstb/resource/1/jvtbd9/v6/i1/p18_s1?isAuthorized=no}
    }
  • Tromp, R. M., E. J. Vanloenen, R. J. Hamers, and J. E. Demuth. 1988. Scanning tunneling microscopy of semiconductor surfaces and interfaces. In The Structure of Surfaces II, .
    [Bibtex]
    @InBook{Hamers513,
    Title = {Scanning tunneling microscopy of semiconductor surfaces and interfaces},
    Author = {Tromp, R. M. and Vanloenen, E. J. and Hamers, R. J. and Demuth, J. E.},
    Year = {1988},
    Series = {Springer Series in Surface Science},
    Type = {Book Section},
    Booktitle = {The Structure of Surfaces II}
    }
  • Tromp, R. M., E. J. van Loenen, R. J. Hamers, and J. E. Demuth. 1988. Scanning Tunneling Microscopy of Semiconductor Surfaces and Interfaces. In The Structure of Surfaces II, Springer Series in Surface Science. .
    [Bibtex]
    @InBook{Hamers526,
    Title = {Scanning Tunneling Microscopy of Semiconductor Surfaces and Interfaces},
    Author = {Tromp, R. M. and van Loenen, E.J. and Hamers, R. J. and Demuth, J. E.},
    Publisher = {Springer Series in Surface Science},
    Year = {1988},
    Type = {Book Section},
    Booktitle = {The Structure of Surfaces II}
    }
  • Avouris, Ph., R. Wolkow, F. Bozso, and R. J. Hamers. Scanning Tunneling Microscopy Studies of the Initial Stages of Thin Film Growth: The Role of Surface Dangling Bonds. Materials Research Society Proceedings 1988, 105, 35.
    [Bibtex]
    @Article{Hamers527,
    Title = {Scanning Tunneling Microscopy Studies of the Initial Stages of Thin Film Growth: The Role of Surface Dangling Bonds},
    Author = {Avouris, Ph. and Wolkow, R. and Bozso, F. and Hamers, R. J.},
    Journal = {Materials Research Society Proceedings},
    Year = {1988},
    Pages = {35},
    Volume = {105},
    Type = {Journal Article}
    }

1987

  • [DOI] Hamers, R. J., P. Avouris, and F. Bozso. IMAGING OF CHEMICAL-BOND FORMATION WITH THE SCANNING TUNNELING MICROSCOPE – NH3 DISSOCIATION ON SI(001). Physical Review Letters 1987, 59, 2071-2074.
    [Bibtex]
    @Article{Hamers280,
    Title = {IMAGING OF CHEMICAL-BOND FORMATION WITH THE SCANNING TUNNELING MICROSCOPE - NH3 DISSOCIATION ON SI(001)},
    Author = {Hamers, R. J. and Avouris, P. and Bozso, F.},
    Journal = {Physical Review Letters},
    Year = {1987},
    Note = {Hamers, rj avouris, p bozso, f},
    Number = {18},
    Pages = {2071-2074},
    Volume = {59},
    Doi = {10.1103/PhysRevLett.59.2071},
    ISSN = {0031-9007},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1987K611000022
    http://prl.aps.org/abstract/PRL/v59/i18/p2071_1}
    }
  • [DOI] Avouris, P., F. Bozso, and R. J. Hamers. THE REACTION OF SI(100) 2X1 WITH NO AND NH3 – THE ROLE OF SURFACE DANGLING BONDS. Journal of Vacuum Science & Technology B 1987, 5, 1387-1392.
    [Bibtex]
    @Article{Hamers281,
    Title = {THE REACTION OF SI(100) 2X1 WITH NO AND NH3 - THE ROLE OF SURFACE DANGLING BONDS},
    Author = {Avouris, P. and Bozso, F. and Hamers, R. J.},
    Journal = {Journal of Vacuum Science \& Technology B},
    Year = {1987},
    Note = {Avouris, p bozso, f hamers, rj},
    Number = {5},
    Pages = {1387-1392},
    Volume = {5},
    Doi = {10.1116/1.583621},
    ISSN = {1071-1023},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1987K494900015
    http://avspublications.org/jvstb/resource/1/jvtbd9/v5/i5/p1387_s1
    http://avspublications.org/jvstb/resource/1/jvtbd9/v5/i5/p1387_s1?isAuthorized=no}
    }
  • [DOI] Demuth, J. E., R. J. Hamers, and R. M. Tromp. IMAGING OF SURFACE ATOMS AND THEIR WAVE-FUNCTIONS WITH THE SCANNING TUNNELING MICROSCOPE. Journal of Vacuum Science & Technology B 1987, 5, 1528-1529.
    [Bibtex]
    @Article{Hamers282,
    Title = {IMAGING OF SURFACE ATOMS AND THEIR WAVE-FUNCTIONS WITH THE SCANNING TUNNELING MICROSCOPE},
    Author = {Demuth, J. E. and Hamers, R. J. and Tromp, R. M.},
    Journal = {Journal of Vacuum Science \& Technology B},
    Year = {1987},
    Note = {Demuth, je hamers, rj tromp, rm},
    Number = {5},
    Pages = {1528-1529},
    Volume = {5},
    Doi = {10.1116/1.583669},
    ISSN = {1071-1023},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1987K494900045
    http://avspublications.org/jvstb/resource/1/jvtbd9/v5/i5/p1528_s1
    http://avspublications.org/jvstb/resource/1/jvtbd9/v5/i5/p1528_s1?isAuthorized=no}
    }
  • [DOI] Koch, R. H. and R. J. Hamers. CHARACTERIZATION OF ELECTRON TRAPPING DEFECTS ON SILICON BY SCANNING TUNNELING MICROSCOPY. Surface Science 1987, 181, 333-339.
    [Bibtex]
    @Article{Hamers285,
    Title = {CHARACTERIZATION OF ELECTRON TRAPPING DEFECTS ON SILICON BY SCANNING TUNNELING MICROSCOPY},
    Author = {Koch, R. H. and Hamers, R. J.},
    Journal = {Surface Science},
    Year = {1987},
    Note = {Koch, rh hamers, rj},
    Number = {1-2},
    Pages = {333-339},
    Volume = {181},
    Doi = {10.1016/0039-6028(87)90174-9},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1987G720900039
    http://www.sciencedirect.com/science/article/pii/0039602887901749}
    }
  • [DOI] Hamers, R. J., R. M. Tromp, and J. E. Demuth. ELECTRONIC AND GEOMETRIC STRUCTURE OF SI(111)-(7X7) AND SI(001) SURFACES. Surface Science 1987, 181, 346-355.
    [Bibtex]
    @Article{Hamers286,
    Title = {ELECTRONIC AND GEOMETRIC STRUCTURE OF SI(111)-(7X7) AND SI(001) SURFACES},
    Author = {Hamers, R. J. and Tromp, R. M. and Demuth, J. E.},
    Journal = {Surface Science},
    Year = {1987},
    Note = {Hamers, rj tromp, rm demuth, je},
    Number = {1-2},
    Pages = {346-355},
    Volume = {181},
    Doi = {10.1016/0039-6028(87)90176-2},
    ISSN = {0039-6028},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1987G720900041
    http://www.sciencedirect.com/science/article/pii/0039602887901762}
    }
  • [DOI] Vanloenen, E. J., J. E. Demuth, R. M. Tromp, and R. J. Hamers. LOCAL ELECTRON-STATES AND SURFACE GEOMETRY OF SI(111)-(SQUARE-ROOT 3 X SQUARE-ROOT 3)AG. Physical Review Letters 1987, 58, 373-376.
    [Bibtex]
    @Article{Hamers287,
    Title = {LOCAL ELECTRON-STATES AND SURFACE GEOMETRY OF SI(111)-(SQUARE-ROOT 3 X SQUARE-ROOT 3)AG},
    Author = {Vanloenen, E. J. and Demuth, J. E. and Tromp, R. M. and Hamers, R. J.},
    Journal = {Physical Review Letters},
    Year = {1987},
    Note = {Vanloenen, ej demuth, je tromp, rm hamers, rj},
    Number = {4},
    Pages = {373-376},
    Volume = {58},
    Doi = {10.1103/PhysRevLett.58.373},
    ISSN = {0031-9007},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1987F688800023
    http://prl.aps.org/abstract/PRL/v58/i4/p373_1}
    }
  • Demuth, J. E., R. J. Hamers, and R. M. Tromp. Scanning Tunneling Microscopy and Spectroscopy of Semiconductor Surfaces. Materials Research Society Proceedings 1987, 77, 1.
    [Bibtex]
    @Article{Hamers524,
    Title = {Scanning Tunneling Microscopy and Spectroscopy of Semiconductor Surfaces},
    Author = {Demuth, J. E. and Hamers, R. J. and Tromp, R. M.},
    Journal = {Materials Research Society Proceedings},
    Year = {1987},
    Pages = {1},
    Volume = {77},
    Type = {Journal Article}
    }
  • Tromp, R. M., E. J. van Loenen, R. J. Hamers, and J. E. Demuth. Scanning Tunneling Microscopy of Semiconductor Surfaces and Interfaces. Proceedings of the Second International Conference onthe Structureof Surfaces 1987, .
    [Bibtex]
    @Article{Hamers525,
    Title = {Scanning Tunneling Microscopy of Semiconductor Surfaces and Interfaces},
    Author = {Tromp, R. M. and van Loenen, E.J. and Hamers, R. J. and Demuth, J. E.},
    Journal = {Proceedings of the Second International Conference onthe Structureof Surfaces },
    Year = {1987},
    Type = {Journal Article}
    }

1986

  • [DOI] Tromp, R. M., R. J. Hamers, and J. E. Demuth. QUANTUM STATES AND ATOMIC-STRUCTURE OF SILICON SURFACES. Science 1986, 234, 304-309.
    [Bibtex]
    @Article{Hamers288,
    Title = {QUANTUM STATES AND ATOMIC-STRUCTURE OF SILICON SURFACES},
    Author = {Tromp, R. M. and Hamers, R. J. and Demuth, J. E.},
    Journal = {Science},
    Year = {1986},
    Note = {Tromp, rm hamers, rj demuth, je},
    Number = {4774},
    Pages = {304-309},
    Volume = {234},
    Doi = {10.1126/science.234.4774.304},
    ISSN = {0036-8075},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1986E304600028
    http://www.sciencemag.org/content/234/4774/304}
    }
  • [DOI] Hamers, R. J., R. M. Tromp, and J. E. Demuth. SCANNING TUNNELING MICROSCOPY OF SI(001). Physical Review B 1986, 34, 5343-5357.
    [Bibtex]
    @Article{Hamers289,
    Title = {SCANNING TUNNELING MICROSCOPY OF SI(001)},
    Author = {Hamers, R. J. and Tromp, R. M. and Demuth, J. E.},
    Journal = {Physical Review B},
    Year = {1986},
    Note = {Hamers, rj tromp, rm demuth, je
    Part 1},
    Number = {8},
    Pages = {5343-5357},
    Volume = {34},
    Doi = {10.1103/PhysRevB.34.5343},
    ISSN = {0163-1829},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1986E450200049
    http://prb.aps.org/abstract/PRB/v34/i8/p5343_1}
    }
  • [DOI] Tromp, R. M., R. J. Hamers, and J. E. Demuth. ATOMIC AND ELECTRONIC CONTRIBUTIONS TO SI(111)-(7X7) SCANNING-TUNNELING-MICROSCOPY IMAGES. Physical Review B 1986, 34, 1388-1391.
    [Bibtex]
    @Article{Hamers290,
    Title = {ATOMIC AND ELECTRONIC CONTRIBUTIONS TO SI(111)-(7X7) SCANNING-TUNNELING-MICROSCOPY IMAGES},
    Author = {Tromp, R. M. and Hamers, R. J. and Demuth, J. E.},
    Journal = {Physical Review B},
    Year = {1986},
    Note = {Tromp, rm hamers, rj demuth, je},
    Number = {2},
    Pages = {1388-1391},
    Volume = {34},
    Doi = {10.1103/PhysRevB.34.1388},
    ISSN = {0163-1829},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1986D348400126
    http://prb.aps.org/pdf/PRB/v34/i2/p1388_1}
    }
  • Demuth, J. E., R. J. Hamers, R. M. Tromp, and M. E. Welland. A SCANNING TUNNELING MICROSCOPE FOR SURFACE SCIENCE STUDIES. Ibm Journal of Research and Development 1986, 30, 396-402.
    [Bibtex]
    @Article{Hamers291,
    Title = {A SCANNING TUNNELING MICROSCOPE FOR SURFACE SCIENCE STUDIES},
    Author = {Demuth, J. E. and Hamers, R. J. and Tromp, R. M. and Welland, M. E.},
    Journal = {Ibm Journal of Research and Development},
    Year = {1986},
    Note = {Demuth, je hamers, rj tromp, rm welland, me},
    Number = {4},
    Pages = {396-402},
    Volume = {30},
    ISSN = {0018-8646},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1986D579400006}
    }
  • [DOI] Hamers, R. J., R. M. Tromp, and J. E. Demuth. SURFACE ELECTRONIC-STRUCTURE OF SI(111)-(7 X 7) RESOLVED IN REAL SPACE. Physical Review Letters 1986, 56, 1972-1975.
    [Bibtex]
    @Article{Hamers292,
    Title = {SURFACE ELECTRONIC-STRUCTURE OF SI(111)-(7 X 7) RESOLVED IN REAL SPACE},
    Author = {Hamers, R. J. and Tromp, R. M. and Demuth, J. E.},
    Journal = {Physical Review Letters},
    Year = {1986},
    Note = {Hamers, rj tromp, rm demuth, je},
    Number = {18},
    Pages = {1972-1975},
    Volume = {56},
    Doi = {10.1103/PhysRevLett.56.1972},
    ISSN = {0031-9007},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1986C111400023
    http://prl.aps.org/pdf/PRL/v56/i18/p1972_1}
    }
  • [DOI] Demuth, J. E., R. J. Hamers, R. M. Tromp, and M. E. Welland. A SIMPLIFIED SCANNING TUNNELING MICROSCOPE FOR SURFACE SCIENCE STUDIES. Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films 1986, 4, 1320-1323.
    [Bibtex]
    @Article{Hamers293,
    Title = {A SIMPLIFIED SCANNING TUNNELING MICROSCOPE FOR SURFACE SCIENCE STUDIES},
    Author = {Demuth, J. E. and Hamers, R. J. and Tromp, R. M. and Welland, M. E.},
    Journal = {Journal of Vacuum Science \& Technology a-Vacuum Surfaces and Films},
    Year = {1986},
    Note = {Demuth, je hamers, rj tromp, rm welland, me
    Part 2},
    Number = {3},
    Pages = {1320-1323},
    Volume = {4},
    Doi = {10.1116/1.573601},
    ISSN = {0734-2101},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1986C819300062
    http://avspublications.org/jvsta/resource/1/jvtad6/v4/i3/p1320_s1
    http://avspublications.org/jvsta/resource/1/jvtad6/v4/i3/p1320_s1?isAuthorized=no}
    }

1985

  • [DOI] Hamers, R. J., P. L. Houston, and R. P. Merrill. DIRECT-INELASTIC AND TRAPPING-DESORPTION SCATTERING OF NO(V=0,J) FROM IR(111) – ANGULAR, VELOCITY, AND ROTATIONAL ENERGY-DISTRIBUTIONS. Journal of Chemical Physics 1985, 83, 6045-6046.
    [Bibtex]
    @Article{Hamers294,
    Title = {DIRECT-INELASTIC AND TRAPPING-DESORPTION SCATTERING OF NO(V=0,J) FROM IR(111) - ANGULAR, VELOCITY, AND ROTATIONAL ENERGY-DISTRIBUTIONS},
    Author = {Hamers, R. J. and Houston, P. L. and Merrill, R. P.},
    Journal = {Journal of Chemical Physics},
    Year = {1985},
    Note = {Hamers, rj houston, pl merrill, rp},
    Number = {11},
    Pages = {6045-6046},
    Volume = {83},
    Doi = {10.1063/1.449640},
    ISSN = {0021-9606},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1985AUR0400094
    http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JCPSA6000083000011006045000001&idtype=cvips&doi=10.1063/1.449640&prog=normal}
    }
  • [DOI] Tromp, R. M., R. J. Hamers, and J. E. Demuth. SI(001) DIMER STRUCTURE OBSERVED WITH SCANNING TUNNELING MICROSCOPY. Physical Review Letters 1985, 55, 1303-1306.
    [Bibtex]
    @Article{Hamers295,
    Title = {SI(001) DIMER STRUCTURE OBSERVED WITH SCANNING TUNNELING MICROSCOPY},
    Author = {Tromp, R. M. and Hamers, R. J. and Demuth, J. E.},
    Journal = {Physical Review Letters},
    Year = {1985},
    Note = {Tromp, rm hamers, rj demuth, je},
    Number = {12},
    Pages = {1303-1306},
    Volume = {55},
    Doi = {10.1103/PhysRevLett.55.1303},
    ISSN = {0031-9007},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1985AQS3900018
    http://prl.aps.org/abstract/PRL/v55/i12/p1303_1}
    }
  • Tromp, R., E. J. Vanloenen, R. J. Hamers, and J. E. Demuth. 1985. Scanning tunneling microscopy of semiconductor surfaces and interfaces. Paper read at Second international conference on the structure of surfaces.
    [Bibtex]
    @InProceedings{Hamers512,
    Title = {Scanning tunneling microscopy of semiconductor surfaces and interfaces},
    Author = {Tromp, R.. and Vanloenen, E. J. and Hamers, R. J. and Demuth, J. E.},
    Booktitle = {Second international conference on the structure of surfaces},
    Year = {1985},
    Type = {Conference Proceedings}
    }

1982

  • [DOI] Hamers, R. J., J. R. Wietfeldt, and J. C. Wright. DEFECT CHEMISTRY IN CAF2-EU3+. Journal of Chemical Physics 1982, 77, 683-692.
    [Bibtex]
    @Article{Hamers297,
    Title = {DEFECT CHEMISTRY IN CAF2-EU3+},
    Author = {Hamers, R. J. and Wietfeldt, J. R. and Wright, J. C.},
    Journal = {Journal of Chemical Physics},
    Year = {1982},
    Note = {Hamers, rj wietfeldt, jr wright, jc},
    Number = {2},
    Pages = {683-692},
    Volume = {77},
    Doi = {10.1063/1.443882},
    ISSN = {0021-9606},
    Type = {Journal Article},
    Url = {<Go to ISI>://WOS:A1982NY11900013
    http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JCPSA6000077000002000683000001&idtype=cvips&doi=10.1063/1.443882&prog=normal}
    }