Bulletin of the American Physical Society
Joint Fall 2011 Meeting of the Texas Sections of the APS, AAPT, and Zone 13 of the SPS
Volume 56, Number 7
Thursday–Saturday, October 6–8, 2011; Commerce, Texas
Session L4: Nanoscience II |
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Chair: Jennifer Steele, Rice University Room: Sam Rayburn Center Second Floor, Room Vision |
Saturday, October 8, 2011 9:25AM - 9:37AM |
L4.00001: Ab initio DFT study of the adsorption of thiol molecules on Au nanoparticles Hector Barron, Lucas Fernandez-Seivane, Monica Olvera de la Cruz, Miguel Jose-Yacaman, Xochitl Lopez-Lozano Recent studies have shown that the Au nanoparticle surface has a strong binding affinity towards thiols, in which the thiol--Au interface allows the surface conjugation of various peptides, proteins, and DNA. Notwithstanding the interaction between Au--Au and thiol--Au are still under debate mainly because of the difficulty to consider a sufficient number of Au-molecule configurations, the large-scale atomistic simulations have been based on old ab initio DFT data, while the process of adsorption have not been completely understood or properly taken into account. In this work the adsorption of methyl-thiol molecules on Au55 gold clusters is investigated by performing density functional theory (DFT) calculations within the generalized gradient approximation (GGA) with the SIESTA code. Different conformations of methyl-thiol-Au55 systems were treated founding that the methyl-thiol molecule prefers to be adsorbed on the Top and Bridge sites, which are energetically more favorable for the adsorption. These results will provide valuable information regarding the fundamental interactions and behavior of methyl-thiol passivated Au nanoparticles. [Preview Abstract] |
Saturday, October 8, 2011 9:37AM - 9:49AM |
L4.00002: Nanowires filled with nanoparticles: application to solar cells Suman Dhayal, Gopal Sapkota, Usha Philipose, Yuri Rostovtsev Gold nanoparticles have interesting properties of nano-antennas that focus the radiation field in relatively small, much smaller than the wavelength of radiation, regions. Optical and electronic properties of nanowires experiencing huge field enhancement can be modified due to these plasmonic interactions. We have developed generalized Mie theory to demonstrate the effect of enhancement of electric field near gold nanoparticles and study the novel optical and electronic properties of these new structures: nanotubes with the pores filled with metal nanoparticles and nanowires with metal naoparticles as inclusions on their surface. In the talk, we discuss the applications of such novel nanoscale hybrid metal/semiconductor composites in applications such as sensitive sensors and efficient photovoltaics. [Preview Abstract] |
Saturday, October 8, 2011 9:49AM - 10:01AM |
L4.00003: STM Studies of Mn$_{12}$-Ph on Highly Oriented Pyrolytic Graphite K. Reaves, K. Kim, Y.G. Kim, K. Itaya, K. Iwaya, T. Hitosugi, H. Zhao, K.R. Dunbar, W. Teizer $\mbox{Mn}_{12}\mbox{O}_{12}\mbox{(}\mbox{C}_6\mbox{H}_5\mbox{COO)}_{16}$ (referred to as $\mbox{Mn}_{12}\mbox{-Ph}$) has been deposited onto Highly Oriented Pyrolytic Graphite (HOPG) which was then observed via Scanning Tunneling Microscopy (STM). $\mbox{Mn}_{12}\mbox{-Ph}$ displays tunneling of quantized magnetization below 3K. In other $\mbox{Mn}_{12}$ ligand variants this magnetic phenomenon can alter the electronic behavior of the molecule, making it a good candidate for a molecular logic gate. At room temperature, film formation was studied to optimize samples for subsequent low temperature studies. At 4.2K isolated objects were observed on the surface clearly distinct from the graphite lattice underneath. Spectroscopic data indicates a bias voltage dependence thought to be associated with metallic-core molecules. [Preview Abstract] |
Saturday, October 8, 2011 10:01AM - 10:13AM |
L4.00004: Transport properties of Sb doped Si nanowires Prathyusha Nukala, Gopal Sapkota, Pradeep Gali, Philipose Usha n-type Si nanowires were synthesized at ambient pressure using SiCl$_{4 }$as Si source and Sb source as the dopant. Sb doping of 3-4 wt {\%} was achieved through a post growth diffusion technique. The nanowires were found to have an amorphous oxide shell that developed post-growth; the thickness of the shell is estimated to be about 3-4 nm. The composition of the amorphous shell covering the crystalline Si core was determined by Raman spectroscopy, with evidence that the shell was an amorphous oxide layer. Optical characterization of the as-grown nanowires showed green emission, attributed to the presence of the oxide shell covering the Si nanowire core. Etching of the oxide shell was found to decrease the intensity of this green emission. A single undoped Si nanowire contacted in an FET type configuration was found to be p-type with channel mobility of 20 cm$^{2}$V$^{-1}$S$^{-1}$. Sb doped Si nanowires exhibited n-type behavior, compensating for the holes in the undoped nanowire. The doped nanowires had carrier mobility and concentration of 160 cm$^{2}$V$^{-1}$S$^{-1}$ and 9.6 x 10$^{18}$cm$^{-3}$ respectively. [Preview Abstract] |
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