Bulletin of the American Physical Society
Joint Fall 2010 Meeting of the Texas Sections of the APS, AAPT, Zone 13 of SPS and the National Society of Hispanic Physicists
Volume 55, Number 11
Thursday–Saturday, October 21–23, 2010; San Antonio, Texas
Session FM5: Condensed Matter and Nanoscience I |
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Chair: M. Yacaman, University of Texas at San Antonio Room: University Center III Ballroom I, 1st floor |
Friday, October 22, 2010 10:00AM - 10:12AM |
FM5.00001: Barium Titanate nanoparticles: using nonlinearity for biomarkers and phase conjugate nano-mirrors Brian Yust, Neema Razavi, Dhiraj Sardar Barium titanate (BaTiO3) is a well known crystal with strong nonlinear optical properties and has been widely used for phase conjugation through four-wave mixing. Recently, it has been reported that these nonlinear properties are still exhibited on the nanoscale. BaTiO3 particles of varying size are synthesized through precipitation and hydrothermal methods and analyzed optically and morphologically. The nonlinear signals from forward four wave mixing and non-degenerate four wave mixing are verified and characterized. The correlation between wave mixing signal strength and particle size is also investigated. Finally, rare earth ions such as neodymium and europium are doped into BaTiO3 particles. Both the fluorescent properties and changes in the nonlinear optical properties are studied. The application of these particles as biomarkers and possible phase conjugate nano-mirrors is also discussed. [Preview Abstract] |
Friday, October 22, 2010 10:12AM - 10:24AM |
FM5.00002: Investigation of the size distribution of nanoparticles produced by Laser Ablation of Microparticles Nathan Erickson, Kay Hoffmann, John Keto Theory has predicted that the size distribution of nanoparticles produced by the Laser Ablation of Microparticles (LAM) process will produce a distribution that follows the log-normal curve. The work that has been done recently in our group investigated for the first time the low end of the predicted log-normal distribution of the LAM process: an area of interest that has been previously eluded observation due to detector resolution. A Wiley-McLaren TOF mass spectrometer was used to detect smaller sized nanoparticles that are traditionally below the resolution of a TEM microscope. [Preview Abstract] |
Friday, October 22, 2010 10:24AM - 10:36AM |
FM5.00003: Holographic Imaging in Carbon Nanotube and Dye-Doped Liquid Crystal Saunab Ghosh, Mikail Abbasov, Gene Carlisle Without application of electric field, we recorded permanent holographic images in the nematic liquid crystal E7, doped with 0.6{\%} Methyl Red (MR) \textit{and} 0.002{\%} single-wall carbon nanotubes (CNTs). The images were recorded using a 488-nm laser and reconstructed using 488-nm, 532-nm and 633-nm probe beams. Multi-order diffraction patterns were observed, during image recording and reconstruction, for thin films having thicknesses of 15 $\mu $m. The quality and diffraction efficiency were higher for cells containing both CNTs and MR than for cells doped only with MR. Average first-order diffraction efficiencies of 7.1{\%} and 3.7{\%} were found for the (CNT+MR)-cells and MR-only cells, respectively. The primary objective of this study was to utilize the molecular properties of MR and CNTs to produce a liquid crystal material with improved holographic properties. Dynamics of image formation and a proposed CNT-enhancement mechanism are presented. The holograms are robust and have remained stable for over two years. [Preview Abstract] |
Friday, October 22, 2010 10:36AM - 10:48AM |
FM5.00004: Down- and Up-Conversion emissions from Er$^{3+}$/Yb$^{3+}$co-doped tellurite glass for solar cell application Madhab Pokhrel, Debnath Radhaballabh , Dhiraj Sardar Monogap solar cells, like silicon solar cells, are unable to absorb the entire solar spectrum. Importantly, photons with high energy are known to have thermalization losses and photons with an energy lower than the band gap energy cannot be absorbed. Materials which convert one UV photon into one or two lower energy photons (down-converters) and materials which convert two or more sub-bandgap photons into high energy photons (up-converters) are of great interest for photovoltaic application. In this work, three properties have been analyzed for Er$^{3+}$/Yb$^{3+}$ co-doped on tellurite glass: (a) we investigate its potential application as a up and down conversion material, (b) investigate the suitability as an enhancer in various solar cells based on band gap engineering, and (c) model to utilize these unique spectroscopic properties in future photovoltaic device as a fluorescent collectors. [Preview Abstract] |
Friday, October 22, 2010 10:48AM - 11:00AM |
FM5.00005: Fluorescence Spectroscopy of Single-Walled Carbon Nanotubes in Epoxy Paul Withey, Kena Senegal, Sarena Senegal, Tamika Thomas, Sergei Bachilo, R. Bruce Weisman Single-walled carbon nanotubes (SWCNTs) have been successfully embedded into EPON 862/W epoxy both with and without a surfactant. Near-infrared fluorescence imaging and spectroscopic studies of individual carbon nanotubes (CNTs) within these nanocomposites indicate very good separation of individual CNTs with little bundling. Application of strain to the nanocomposites permitted the interfacial adhesion between the CNT and host to be studied at the single-particle level. Shifts in the emission spectrum of individual semiconducting SWCNTs clearly indicate load transfer. Loss of adhesion, or slipping, has also been detected for some nanotubes as changes in their emission spectra. Near-infrared fluorescence imaging and spectroscopy are proving to be ideal methods for monitoring the behavior of SWCNTs within nanocomposites, especially at the single-particle level. Much of this work has been carried out by undergraduate physics and chemistry majors. [Preview Abstract] |
Friday, October 22, 2010 11:00AM - 11:12AM |
FM5.00006: Investigation of Eu doped TiO$_{2}$ thin films Edward Khachatryan, Erik Enriquez, Francisco Pedraza, Chonglin Chen, Dhiraj Sardar We present second harmonic generation from Eu doped Titanium oxide (Ti O$_{2})$ thin films deposited on different substrates (glass, Si, LaAlO$_{3}$, MgO)by sputtering in different conditions. Atomic Force Microscope (AFM) was used to measure the grain size and the boundaries of the samples. Transmission Electron Microscope (TEM) was applied to study the morphology, crystal structure and for interface imaging. Spectroscopic characterization and comparison between different deposition conditions and substrates also will be presented. [Preview Abstract] |
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