Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 57, Number 11
Friday–Saturday, October 26–27, 2012; Socorro, New Mexico
Session C4: Materials Physics II |
Hide Abstracts |
Chair: Jean-Francois Van Huele, Brigham Young University Room: Macey Center Galena |
Friday, October 26, 2012 1:15PM - 1:39PM |
C4.00001: Living On The Edge Invited Speaker: Boris Kiefer Computational Physics continuous to significantly advance our understanding of the natural world that surrounds us. However, and may be even more importantly is the observation that computational models have reached a degree of sophistication that provides them with predictive power and reliability which are prerequisites for the successful integration of these techniques into the exploration and design of novel materials. One such effort is the area of energy conversion technologies for non-stationary applications that reduce the emission of greenhouse gases and increase energy independence and security. Fuel cells are among the prime candidates for such a technology. However, overcoming the performance limiting sluggish oxygen-reduction-reaction (ORR) at the cathode and the replacement of expensive and rare platinum catalysts remain challenging. I will discuss our contribution to gain new and innovative insights for the design and the performance of alternative TM-N$_{x}$ (TM=Fe, Co, Ni, x=2,4) derived catalysts. Chemically altered graphene serves as a model system for the density-functional-theory based exploration of the ORR on these catalysts in alkaline and acidic media and for comparison with available experimental results. [Preview Abstract] |
Friday, October 26, 2012 1:39PM - 1:51PM |
C4.00002: Microwave microscopy of electrical and magnetic properties of graphene and graphite Nikolai Kalugin, Christopher Del Barga, Lee Wickey, Mekan Ovezmyradov, Eric Shaner, Aaron Gin, Vladimir Talanov The investigation of microwave properties of graphene and graphite is an important practical and scientific problem. The results of microwave measurements of graphene and graphite obtained using near-field scanning microwave microscopy, with the probe formed by an electrically open end of a 4 GHz half-lambda parallel-strip transmission line resonator, allow to develop a quantitative electrodynamic model of graphene microwave impedance. Investigations of the magnetic properties of graphene and graphite have recently attracted significant attention. The results of near-field scanning superconducting quantum interference device (SQUID) RF microscopy of graphite and graphene at 200 MHz show that screening currents induced in the sample by an external RF magnetic field tend to localize near defects. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No.DE-AC04-94AL85000.. [Preview Abstract] |
Friday, October 26, 2012 1:51PM - 2:03PM |
C4.00003: The optical properties of using graphene as a saturable absorber Nathan Keschl, Thomas Schibli, Chien-Chung Lee, Wanyan Xie Graphene, a single-atom layer of carbon atoms in a honeycomb lattice, has been on the forefront of research since it's discovery in 2005 [1]. Although it has many applications, my research is specialized in the field of utilizing the graphene as a saturable absorber for mode-locking lasers. Currently, the most common method to mode-lock a laser is by using a Semi-conductor Saturable Absorber Mirror (SESAM). Graphene is a substitute for SESAMs with pulse generation as low as 260 fs [2]. However, graphene will begin to ``burn'' as the laser approaches the intensity it needs to mode-lock. We have experimented with various methods of protecting the graphene from burning so it can be used at higher intensity domains.\\[4pt] [1] A. K. Geim, K. S. Novoselov, ``The rise of graphene.'' Nat Mater. 2007/03//print\\[0pt] [2] G. Acosta, J.S. Bunch, C.C. Lee, T.R. Schibli, ``Ultra-Short Optical Pulse Generation with Single-Layer Graphene.'' Journal of Nonlinear Optical Physics and Materials, Volume 19, Issue 04, pp. 767-771. 00/2010. [Preview Abstract] |
Friday, October 26, 2012 2:03PM - 2:15PM |
C4.00004: Ab initio study of single and double vacancies in graphene Mahmoud Hammouri, Igor Vasiliev Graphene is a promising material for semiconductor engineering and other applications. The introduction of point defects such as vacancies can make graphene a magnetic material. We calculate the density of states and the band structure of a single and double vacancy in a graphene using periodic supercell containing 64, 72, and 128 carbon atoms. Our calculations are performed using the SIESTA density functional electronic structure code combined with the generalized gradient approximation for the exchange correlation functional. [Preview Abstract] |
Friday, October 26, 2012 2:15PM - 2:27PM |
C4.00005: The Physics and Chemistry of Carbon Cages Robert Courtney, Boris Kiefer Carbon nano-structures have been an area of exciting developments in recent years. A unique set of these structures are carbon fullerenes which are similar to ``bucky balls.'' These spherical cages have varying degrees of roundness, and are found in single and multi-shell configurations. Restructuring of the hybridized bonds between the carbon atoms is thought to contribute to the roundness of the structure, as well as the difference in energy between the multi-shell and single shell structures. In addition, removal or restructuring of bonds can create potential for functionalization of the structure's surface. We will discuss modes of bond hybridization which lend themselves to functionalization and can lead to increased solubility in polar solvents. This leads to possibilities for applications in biological systems, of which we will specifically address targeted tissue drug delivery. [Preview Abstract] |
Friday, October 26, 2012 2:27PM - 2:39PM |
C4.00006: Ultrafast pump-probe measurements of thermal transport in nanospheres Brian Green, Mark Siemens Macroscopic thermal transport is explained by classical thermal diffusion, but as nanostructure length scales approach the phonon mean free path, thermal transport is no longer diffusive, but ballistic in character. We present experimental measurements in which we time-resolve the cooling dynamics of gold nanospheres approximately 100 nm in diameter on a glass substrate. We use a transient thermoreflectance technique, utilizing a near-infrared ultrafast pulsed laser in collinear pump/probe experiments. The measured thermal dynamics show sub-picosecond heating and a biexponential decay. Fitting these experimental data with a diffusive thermal transport model provides physical insight into the relevant length and time scales in these nanostructured systems. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700