Bulletin of the American Physical Society
2011 Annual Meeting of the Four Corners Section of the APS
Volume 56, Number 11
Friday–Saturday, October 21–22, 2011; Tuscon, Arizona
Session M2: Carbon Nanostructures II |
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Chair: Brian LeRoy, University of Arizona Room: UA Student Union Ventana |
Saturday, October 22, 2011 11:10AM - 11:22AM |
M2.00001: Ultrasonic Spraying Thin Films of Carbon Nanotubes Anthony Willey, Robert Davis, Richard Vanfleet, Amy Balls, Jonathan Abbott Carbon nanotubes have many interesting and useful properties, especially in terms of strength and electrical conductivity. However, they can be hard to work with because they are held together in bundles by strong Van der Waals forces. Much work has been performed in the ultrasonic spraying of liquid suspensions of single and multi-wall carbon nanotubes. The resulting thin films have a variety of applications, including electron transport in thin film photovoltaics. [Preview Abstract] |
Saturday, October 22, 2011 11:22AM - 11:34AM |
M2.00002: Effect of interactions and degeneracy on transmission through a single molecule Michael Stefferson, Jarred Hudson, Charles Stafford Electron transmission through a single-molecule junction in the Coulomb blockade regime is analyzed in the isolated resonance approximation for molecules with degenerate HOMO and/or LUMO orbitals. Electron-electron interactions are included in a capacitive charging model derived from pi-electron effective field theory. For the case of a buckyball junction with Pt electrodes, we find that the number of transmission channels is limited by the five-fold degenerate HOMO resonance. [Preview Abstract] |
Saturday, October 22, 2011 11:34AM - 11:46AM |
M2.00003: Effective Field Theory of Interacting $\pi$-Electrons in Highly-Conductive Molecular Junctions Joshua Barr, Justin Bergfield, Charles Stafford We present an effective field theory ($\pi$-EFT) that allows the two-body Hamiltonian for a $\pi$-electron system to be expressed in terms of three effective parameters: the $\pi$-orbital quadrupole moment, the on-site repulsion, and a dielectric constant. As an application of this, we then present a model of screening effects in single-molecule junctions based on the image multipole method, and review our recent application of this to highly-conductive molecular junctions wherein the transmission eigenchannel distribution calculated for an ensemble of Pt-benzene-Pt junctions is in excellent agreement with experiment. [Preview Abstract] |
Saturday, October 22, 2011 11:46AM - 11:58AM |
M2.00004: Scanning tunneling spectroscopy of CVD graphene Daniel Cormode, Brian LeRoy We investigate the electronic properties of large crystal CVD grown graphene using scanning tunneling microscopy. Mono- and bilayer crystals were prepared by transferring graphene from copper onto exfoliated boron nitride flakes on 300 nm SiO$_2$ substrates. The boron nitride provides an ultra flat surface for the graphene. Samples were measured in ultra high vacuum by scanning tunneling spectroscopy at 5 K. In these experiments, we have investigated the effect of two types of charged impurities, either random impurities from the growth process or controlled doping of the graphene with potassium atoms. Potassium atoms are controllably deposited on the graphene at low temperature by heating a getter source. [Preview Abstract] |
Saturday, October 22, 2011 11:58AM - 12:10PM |
M2.00005: Ab Initio Study of the Interaction between Dopant Atoms and Point Defects in Graphene Tarek Tawalbeh, Igor Vasiliev We apply a first-principles computational method based on density functional theory to study the interaction of substitutional boron (B) and nitrogen (N) atoms with Stone-Wales defects and vacancies in graphene. Our calculations are carried out using a pseudopotential technique combined with the generalized gradient approximation for the exchange-correlation functional implemented in the SIESTA (Spanish Initiative for Electronic Simulations with Thousands of Atoms) electronic structure package. Graphene sheets are modeled by periodic supercells containing up to 160 atoms. The equilibrium geometries, total energies, electronic structures, and densities of states of doped and defective graphene sheets are examined as a function of the separation distance between dopant atoms and point defects in graphene. [Preview Abstract] |
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