Bulletin of the American Physical Society
Joint Fall 2009 Meeting of the Texas Sections of the APS, AAPT, and SPS
Volume 54, Number 13
Thursday–Saturday, October 22–24, 2009; San Marcos, Texas
Session D1: Poster Session (4:00-6:00PM) |
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Chair: Anup Bandyopadhyay, Texas State University Room: LBJ Student Center 3-11.1 and 3-12.1 |
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D1.00001: Dynamic Response and Locking of Optical Resonators for LIGO Sergio H. Cantu, Liliana Ruiz-Diaz, Alan Farrell, Malik Rakhmanov The Laser Interferometer Gravitational Wave Observatory (LIGO) is a large-scale detector capable of direct observation of gravitational waves from various astrophysical sources. The detector utilizes a highly stabilized laser beam which requires a high-purity mode content. The spatial filtering (modecleaning) of the laser beam is done by a triangular ring resonator (Fabry-Perot cavity), which is made of a monolithic fused-silica spacer and low-loss mirrors bonded to it with precision alignment. We fabricated and characterized 3 such ring resonators at the LIGO Hanford Observatory. Several measurement techniques have been applied to measure the optical losses in these resonators. In this poster we present the results of these measurements and provide physical explanation of the resonator filtering properties. [Preview Abstract] |
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D1.00002: Evaluating Molecular Hyperpolarizabilities with MOPAC Sean Smith, Steven Alexander Molecules with high second-order nonlinearities have a number of industrial applications including high-speed low-power electronics. Accurate calculations can help identify molecules that have these properties. We have used the MOPAC semiempirical molecular orbital program to calculate the first order hyperpolarizabilities for several molecules and we compare these results to the experimental values reported in the literature. There is good correlation between these two data sets for most of the molecules though some have hyperpolarizabilities that differ by several orders of magnitude. [Preview Abstract] |
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D1.00003: Quantum Description of Diffraction of Light by a Multiple Slit: The Heuristic Value of the Correspondence Principle Daniel Dominguez, Luis Grave-De-Peralta We explore the classical limit of the quantum description of the multiple-slit interference phenomena. We present a detailed and quantitative quantum description of the diffraction patterns obtained in multiple-slit experiments with relatively intense light. This is achieved with no more mathematical complexities than the required by a classical description. We have based our quantum description of interference on seminal ideas first introduced by Dirac and Feynman combined with the application of the Bohr's correspondence principle, i.e., the classical description of the interference phenomena should be in some way a limit case of the quantum theory. [Preview Abstract] |
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D1.00004: Near-Infrared Quantum Cascade Laser Based on the Intra-Cavity Second Harmonic Generation Yong Hee Cho, Alexey Belyanin We propose and theoretically analyze quantum cascade lasers operating in the near-infrared range due to the intra-cavity second harmonic (SH) generation. The latter process involves high lying subbands in the conduction band. Thus it requires an accurate determination of the band structure above $\sim $1eV from the bottom of the conduction band. Here we adopted a multiband k$\cdot$p model to achieve it. The fundamental laser power is converted to the second harmonic laser power due to large resonant nonlinearity in the properly designed heterostructure. We show that the modal phase matching between EH$_{00}$ (fundamental) and EH$_{20}$ (second harmonic) modes is possible in ridge waveguides and their output powers are predicted based on the density matrix formalism. At current density J=8.5kA/cm$^{2}$, the second harmonic power of 0.14 mW is obtained with the conversion efficiency of 0.2mW/W$^{2}$ in GaInAs/AlAsSb/InP heterostructures. [Preview Abstract] |
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D1.00005: Simulation of transpolar potential saturation for northward IMF Shree Bhattarai, Ramon Lopez, Robert Bruntz, Elizabeth Mitchell, Sophia Cockrell, John Lyon, Michael Wiltberger When the Interplanetary Magnetic Field (IMF) is strongly southward, the potential across the ionosphere reaches a saturation value and does not increase substantially, even of the IMF becomes much more strongly negative. Recent observations have indicated that the same thing happens for strongly northward IMF. We will present global MHD simulations of this phenomenon using the Lyon-Fedder-Mobarry simulation code and make comparisons to observations from the DMSP spacecraft. We also will show that the behavior of the saturation effect is consistent with a recent explanation for saturation based on the forces on the flow in the magnetosheath. [Preview Abstract] |
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D1.00006: Testing a New Method of Detecting RR Lyrae Variable Stars W. Lee Powell Jr., Talitha Muehlbrad, Ronald Wilhelm, Dylan Ginn, Andrew Jastram We have submitted for publication a new method of selecting candidate RR Lyrae stars using out-of-phase single epoch photometric and spectroscopic observations contained in SDSS Data Release 6 (DR6). The technique detects variability by exploiting the large disparity between the (g - r) color and the strength of the Hydrogen Balmer lines when the two observations are made at random phase. The SDSS Stripe 82 allowed us to show that our method has a discovery efficiency of $\sim $85{\%}. This technique has yielded over 1,000 candidates fainter than g = 14.5. We present the results of observations of several of these candidates made on the 0.8m telescope at McDonald Observatory, with 10 of 11 confirmed as variable and one labeled as a likely RRc. We also examine the use of clumping in the suspected variables to probe galactic structure, both known and new. [Preview Abstract] |
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D1.00007: Plausible Explanation of Quantization of Intrinsic Redshift from Hall Effect and Weyl Quantization Florentin Smarandache, Vic Christianto Using phion condensate model as described by Moffat, we consider a plausible explanation of (Tifft) intrinsic redshift quantization as described by Bell as result of Hall effect in rotating frame. We also discuss another alternative to explain redshift quantization from the viewpoint of Weyl quantization, which could yield Bohr-Sommerfeld quantization. [Preview Abstract] |
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D1.00008: Casimir Effect and its Applications to Biophysics Phu Nguyen, Mike Cabrera, Channing Moeller, Samina Masood The Casimir Effect is re-examined at finite temperature and density. The Casimir force is computed with different parameters to study its applications to physical systems like carbon nanotubes and even the protein folding. In the protein folding we compare the Casimir force with the Vander Waals forces and the hydrophobic interaction. [Preview Abstract] |
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D1.00009: Prefibrillar Formation Conditions of $\beta $-Lactoglobulin by Titration and Chaotropes Urea and KSCN Under Thermal Load Jeremiah Babcock, Rolando Valdez, Lorenzo Brancaleon The harmful growth of toxic oligomers in the formation of protein amyloid fibrils have been connected to degenerative diseases like Alzheimer's and Huntington's diseases. Understanding the fundamental mechanisms behind protein unfolding and subsequent fibrillogenesis may provide a way to stop the process from occurring. The purpose of this study was to identify favorable fibril growth conditions for a globular model protein $\beta $-lactoglobulin using the chaotropes urea and KSCN, along with titration of a pH 7.04 phosphate buffer solution at 40 $^{\circ}$C over five days. Time-resolved and steady-state fluorescence was used to examine the shift in emission of the tryptophan amino acids over the applied denaturation ranges. ${\rm B}$LG, a dimer in native form, monomerized and partially unfolded at 5 M Urea, 2 M KSCN and at pH 2 in phosphate buffer \textit{in vitro}. Exposure of the solutions to continuous heat over time caused a increase in the lifetimes and red shift in the emission spectra, indicating the possible beginning of nucleation. The study has provided a base for continuation of the study of oligomerization and subsequent fibrillation of BLG, which may provide a fundamental mechanism of formation transferable to other proteins \textit{in vivo}. [Preview Abstract] |
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D1.00010: Photophysical Characterization of DMOP, DOOP, and PDO After Irradiation Sarah Rozinek, Jorge Palos-Ch\'avez, Lorenzo Brancaleon, Mark A. Penick, Mathew P.D. Mahindaratne, George R. Negrete The photophysical properties of perylene and its derivatives are remarkably useful for organic photovoltaic systems including organic solar cell photoacceptors, molecular sensors, and fluorescent labels for analytical applications. A series of uncharacterized novel 3,9-dialkyloxy- and diacyloxyperylenes perylene analogues (3,9-dimethoxyperylene, DMOP, 3,9-bis(1-octyloxy)perylene, DOOP, and novel 3,9-bis(1-octanoyloxy) perylene, PDO) were developed. This study examined the stability of these perylene derivatives within a range of solvents after exposure to 405nm irradiation at various intensities and durations. Absorption spectroscopy, fluorescence spectroscopy, and fluorescence lifetime decay using time-correlated single photon counting were preformed. Preliminary results indicate that DMOP, DOOP, and PDO are highly stable in pyridine, slightly less stable in tetrahydrofuran (THF), more interesting in chloroform, and least stable in carbon tetrachloride (CCl4). In the right solvent they may be successfully incorporated into organic solar cells and other photovoltaic systems. [Preview Abstract] |
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D1.00011: Growth and Characterization of Multilayer Structures Kunal Bhatnagar, Ravi Droopad, Toni Sauncy Molecular Beam Epitaxy (MBE) is an advanced atomic precision epitaxial deposition technique that utilizes Ultra High Vacuum conditions for optimal crystal growth. Recently, new MBE facilities have been installed at Texas State University. The facility includes growth chambers for III-V compound semiconductor, Si, II-VI semiconductors and analysis chambers for SEM, XPS, LEED and other characterization techniques. Several novel structures have been produced and analyzed using characterization facilities at Angelo State University, namely Spectroscopic Ellipsometry(SE). SE is a non-destructive thin film characterization technique used for determining film thickness, interfacial roughness and optical properties of multilayered structures. Gadolinium Gallium Oxide(GdGaO3) is one material that is important as a high-k dielectric in compound semiconductor MOSFET application and has not been characterized very well using ellipsometry. Ellipsometric data will be presented for GaGdO3 on GaAs and optical properties will be discussed. [Preview Abstract] |
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D1.00012: Desorption Kinetics of Dodecanethiol Self-Assembled Monolayers Grown on Cr$_{2}$O$_{3}$(0001)/Cr(110) Christopher Cumby, Jennifer Walters, Nicholas Clark, Heike Geisler, Carl Ventrice The most common method of growing self-assembled monolayers (SAMs) is by immersion of the substrate in solution, which limits the experiment to inert surfaces such as gold or silver. In this experiment, SAMs of dodecanethiol were grown under ultra-high vacuum (UHV) conditions on Cr$_{2}$O$_{3}$(0001)/Cr(110). The adsorption geometry of the SAM was monitored with low energy electron diffraction (LEED) and the desorption kinetics were measured via temperature programmed desorption (TPD). For SAM growth on substrates held at 120 K, a multilayer peak is observed at 240 K and the monolayer peak at 480 K for a heating rate of 25 $^{\circ}$C/min. TPD measurements at different heating rates are being performed to determine the activation energy for desorption. [Preview Abstract] |
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D1.00013: Measurement of the Adsorption Kinetics of CO and CO$_{2}$ on Cr(110) Jennifer Walters, Alan Harrison, Christopher Cumby, Gabriel Arellano, Heike Geisler, Carl Ventrice Previous studies of the adsorption of CO on the catalytically active Cr(110) surface have found that the CO molecule dissociates upon adsorption at 300 K. One aspect of the CO adsorption process that has not been studied in detail is the temperature dependence of the dissociation and the influence of oxygen on the dissociation process. Therefore, we have performed temperature programmed desorption (TPD) and low energy electron diffraction (LEED) studies of the adsorption of CO, CO with oxygen, and CO$_{2}$ on the Cr(110) surface. Deposition of CO was performed at 120 K on either the clean or oxygen dosed Cr(110) surface before performing the TPD measurements. For deposition below 0.5 Langmuir (L), no CO is detected with TPD, which indicates that all of the CO is dissociating and reacting with the Cr(110) surface. As the CO dose is increased, a broad peak centered at 300 K is first observed, followed by a second peak at 200 K. Oxygen coadsorption increases the rate at which the CO desorption is observed but does not result in CO$_{2}$ desorption. For comparison, TPD measurements have also been performed for adsorption of CO$_{2}$ at 120 K. [Preview Abstract] |
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D1.00014: Investigation of the positron Doppler broadening for rubber samples below the glass transition temperature Amanda Towry, C.A. Quarles Previous research [K. Sato, et al., Phys. Rev. B71 (2005)012201; C. Quarles, et al., Nucl. Inst. Meth. Phys. Res. B 261(2007)875-878] has demonstrated a correlation between the Doppler broadening S parameter and the intensity of the ortho-positronium lifetime component in polymers which depends on the composition of the polymer. On the other hand, rubber polymers do not show this correlation and behave more like liquids for which the S parameter is essentially independent of the ortho-positronium intensity. The difference between the rubber samples and most polymers studied is that the rubbers were all above the glass transition temperature (T$_{G})$ at room temperature. The bubble model in the rubber has been suggested as an explanation of this behavior in analogy with liquids. This research reports the measurement of the S parameter for seven rubber samples below T$_{G}$ where the bubble model would not be expected to work. The results were obtained by immersing the samples and a Na-22 source in liquid nitrogen. We will discuss how the results below T$_{G}$ impact the hypothesis of bubble formation in the rubber above T$_{G}$. [Preview Abstract] |
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D1.00015: Characterization of functionalized carbon nanotubes and their composites Z.P. Luo, L. Carson, L. Adams, N. Soboyejo, A. Oki, E.G.C. Regisford Carbon nanotubes (CNTs) have received considerable attention due to their extraordinary properties of strength, toughness, as well as thermal and electrical conductivities. They are ideal fillers for polymer nanocomposites to enhance the composite physical and mechanical properties. In order to overcome the problem of tangling caused by intrinsic van der Waals forces during the composite fabrication, chemical functionalization process has been introduced. In this work, we characterized the chemical coating on the functionalized CNTs and their composites using analytical electron microscopy. It was observed that the CNT surfaces were coated with reactants from the chemical reactions. In the CNT/epoxy nanocomposites, such a coating significantly improved the CNT dispersion. In the CNT/chitosan composite, it was observed that the unfunctionalized CNTs without coating did not bond with the chitosan particles, while the functionalized CNTs could bond with the chitosan particles through the surface adhesive coating, which is an ideal medium to make the CNT/chitosan composites. [Preview Abstract] |
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D1.00016: Losses in Particle Photovoltaic cells Hector Valdez, Wilehlmus Geerts, Lawrence Larson The power output of a Si photovoltaic cell is limited by the optical and electrical losses amongst several other effects. Reflection out of the Si and shading by the electrical contacts will limit the number of photons that will be able to generate electron hole pairs near the pn-junction. Recombination of charge carriers in and near the depletion area will decrease power resulting in an effective~shunt resistance. The contact- and spreading resistance of the electrodes further reduce the power output. In this paper we will theoretically compare the efficiency of a PV cell configuration consisting of an array of silicon particles with the efficiency of a conventional style PV Si cell. [Preview Abstract] |
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D1.00017: Entangled States and Quantum Causality Threshold in General Theory of Relativity Dmitri Rabounski, Florentin Smarandache This article shows, Synge-Weber's classical problem statement about two particles interacting by a signal can be reduced to the case where the same particle is located in two different points A and B of the basic space-time in the same moment of time, so the states A and B are entangled. This particle, being actual two particles in the entangled states A and B, can interact with itself radiating a photon (signal) in the point A and absorbing it in the point B. That is our goal, to introduce entangled states into General Relativity. Under specific physical conditions the entangled particles in General Relativity can reach a state where neither particle A nor particle B can be the cause of future events. We call this specific state Quantum Causality Threshold. [Preview Abstract] |
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D1.00018: jSynthesizer: A Java based first-motion synthetic seismogram tool Mark Sullivan Both researchers and educators need software tools to create synthetic seismograms to model earthquake sources. We have developed a program that generates first-motion synthetic seismograms that is highly interactive and suited to the needs of both research and education audiences. Implemented in the Java programming language, our program is available for use on Windows, Mac OS X and Linux operating systems. Our program allows the user to input the fault parameters strike, dip and slip angle, numerically or graphically using a lower hemisphere equal-area stereographic projection of the focal sphere of the earthquake. This representation is familiar to geologists and seismologists as the standard way of displaying the orientation of a fault in space. The user is also able to enter the relative location of the seismograph and the depth and crustal velocity structure in the vicinity of the earthquake. The direct P wave along with reflections off of layer boundaries near the source are generated using a constant ray-parameter approximation. The instrument response functions used by the Worldwide Standardized Seismogram Network and the attenuation response of the Earth's mantle are generated in the frequency domain and applied to generate the synthetic seismogram. Planned enhancements to this program will allow the simultaneous generation of seismograms at many stations as well as more complicated crustal structures. [Preview Abstract] |
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D1.00019: Characterization of Electronics and Software in QUARTIC Detectors for High-Energy Physics Ryan Hall Precision timing is necessary in detector systems for high-energy physics applications, specifically, experiments conducted in large accelerators. The capabilities of the microchannel-plate photomultipler tubes (MCP-PMTs) proposed for use in much of this research as sensing devices are not fully known, and several models exist only at a prototype level. Our group is testing various configurations of electronics and software, including constant-fraction discriminators and high-frequency amplifiers, in order to establish a time-of-flight precision on the order of 10 ps (10e-12 s). In that amount of time, light travels 3mm. The experiment focuses on the QUARTIC detector design, which utilizes an array of quartz bars as a medium to generate and collect photons emitted by incident particles travelling faster than the local speed of light. By simulating this Cerenkov radiation using a picosecond pulse laser of controlled intensity and frequency, we intend to design and improve a system to assist in screening for possible Higgs signatures in events observed in the ATLAS experiment at the Large Hadron Collider (LHC). Currently, our best results give a spread in measured time values on the order of 28 ps, but using statistical methods over multiple simultaneous measurements can reduce the uncertainty to approximately 16 ps. [Preview Abstract] |
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D1.00020: Finite element analysis of bridge steel pedestal anchor bolts in reinforced concrete B. Logan Hancock, Monique Hite Head Steel pedestals are short, column-like structures currently being used to elevate highway bridges to reduce the risk of collisions with over-height vehicles. Previous full-scale experimental research has been done to examine the efficacy of these steel pedestals and their components under quasi-static loading to evaluate any added instability in the event of an earthquake. As part of the Undergraduate Summer Research Grant (USRG) program at Texas A{\&}M University, this specific project was focused on observing the behavior of the post-installed steel pedestal anchor bolts under applied shear and tensile loading using the finite element (FE) software Abaqus. The results from some of the preliminary analyses are compared to theoretical anchorage calculations with the aim of producing a benchmark for future steel pedestal anchor bolt embedment design. Future research improvements regarding FE modeling and structural design suggestions are proposed as well. [Preview Abstract] |
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D1.00021: The Center for Nanostructured Materials: A User Facility at The University of Texas at Arlington Muhammed Yousufuddin The Center for Nanostructured Materials (CNM) located at the University of Texas at Arlington is a fully equipped user facility that houses a variety of instrumentation for the characterization of nanomaterials. Several state-of-the-art characterization techniques are available including Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS), Electron Paramagnetic Resonance (EPR), Raman Spectroscopy, Superconducting Quantum Interference Device (SQUID), and X-ray Diffraction of thin films, powders, and single crystals. The range of instrumentation supports interdisciplinary collaborations in physics, chemistry and materials science and provides an excellent resource for training undergraduate and graduate students. The primary goal of CNM is to foster interdisciplinary collaborations for a wide range of researchers and as such we welcome all potential users. In this presentation I will discuss CNM's capabilities and user access policies. [Preview Abstract] |
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D1.00022: Effects of radiation on the electro-optical properties of nanoparticle-polymer-dispersed liquid crystal structures Alfonso Hinojosa, Cecil Shive, Suresh Sharma Polymer dispersed liquid crystals (PDLCs) are composite materials consisting of submicron-size droplets of liquid crystal (LC) embedded within a polymer. By using holographic techniques, PDLCs can be transformed into periodic structures with spatial periodicity (HPDLCs), which can be controlled within reasonable limits by experimental parameters. Consequently, the optical properties of HPDLC-based devices, e. g., diffraction efficiency can also be controlled [1]. These periodic structures are used in numerous electro-optical devices; e. g., switchable holographic gratings and photonic bandgap structures. We have shown previously that the light transmission through PDLCs changes upon irradiation by gamma-rays [2]. In order to evaluate the means by which the sensitivity of these materials to radiation can be improved, we have synthesized hybrid materials consisting of nanoparticles and HPDLC periodic structures. By utilizing a high sensitivity optical characterization technique, we have carried out measurements of the luminescence properties of these materials with/without irradiation. Here, we present the resulting data and discuss the consequences of embedding nanoparticles into these structures. [1] R. A. Ramsey et al., Appl. Phys. Letts. \textbf{88}, 051121 (2006). [2] S. C. Sharma et al., Phys. Rev. Letts, \textbf{87}, 105501 (2001) [Preview Abstract] |
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D1.00023: Chemical vapor deposition of nanodiamonds and study of their structural, optical, and electronic properties Rajarshi Chakraborty, Kyle La Roque, Suresh Sharma Diamond thin films were grown on silicon substrates by hot-filament assisted chemical vapor deposition technique utilizing CH$_{4}$ and H$_{2}$ mixtures. During our investigations of diamond thin films in the 1990's, the emphasis was on the growth of continuous thin diamond films with exceptional structural, electronic, and electrical properties [1]. However, there is now renewed interest in the growth and unique properties of nanometer-size diamond [2]. We have, therefore, re-examined some of our previously grown diamond samples with emphasis on delineating the structural and optical properties of nanometer-size diamond particles in these samples. The nanoparticles are characterized by using AFM, SEM, XPS, and Raman spectroscopy. The optical properties of the nanoparticles are further studied by carrying out photoluminescence measurements. In this contribution, we briefly review different growth techniques and present our results on the structure and optical properties of nanodiamonds. \\[4pt] [1] S. C. Sharma et al., J. Materials Research, \textbf{5}, 2424 (1990)\\[0pt] [1] J. P. Boudou et al., Nanotechnology, \textbf{20}, 235602 (2009) [Preview Abstract] |
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D1.00024: Growth of Single-Layer Graphene on Pt(111) by Thermal Decomposition of Propylene Gregory Hodges, Heike Geisler, Carl Ventrice Graphene, which is a one-atom-thick layer of sp$^{2}$-bonded carbon, has sparked keen interest within the scientific community because it is predicted to have a wide range of unique properties. In particular, it has one of the highest known mobilities of all the semiconducting materials. Since its discovery in 2004, there have been several studies of the growth of graphene by various techniques. We have performed studies on the growth of graphene on the catalytically active Pt(111) surface by thermal decomposition of propylene in an ultra-high vacuum (UHV) chamber. Two methods have been used: deposition of a monolayer of propylene followed by annealing in UHV and growth of graphene in an atmosphere of 10$^{-6}$ Torr of propylene at 500 $^{\circ}$C. The crystal structure of the graphene films was monitored using low energy electron diffraction (LEED). In addition, we are currently performing high resolution electron energy loss spectroscopy (HREELS) measurements of the electronic structure of the graphene films. [Preview Abstract] |
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D1.00025: Design and Construction of a Scanning Tunneling Microscope for Atomic Scale Imaging of Surfaces in Ultra-High Vacuum Robert Kilbourn, Carl Ventrice, Sten Thornburg, James Burst, Vincent LaBella The outer layer of atoms of most materials either relax or reconstruct, which often results in a change in the electronic, magnetic, and/or chemical properties. Therefore, we have designed and constructed a scanning tunneling microscope (STM) for use in an ultra-high vacuum (UHV) based surface analysis system in the Surface Science Laboratory at Texas State. The instrument is capable of producing atomic-scale images on single crystal samples and allows transfer of samples to the horizontal manipulator of the system for surface preparation and high-resolution electron energy loss spectroscopy (HREELS) measurements. The main body of STM is constructed from Macor, which is UHV compatible and has a high strength to weight ratio, low thermal expansion coefficient, and low thermal conductivity. The instrument is mounted with springs with a 16'' expansion length and has a resonant frequency of $\sim $1 Hz. The tube scanner is mounted to a UHV compatible inchworm for coarse approach. Custom designed analog electronics and software are used to control the instrument. [Preview Abstract] |
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D1.00026: Spectroscopic analysis of urinary calculi and inhibition of their growth Felicia Manciu, William Durrer, Jayesh Govani, Layra Reza, Luis Pinales We present here a study of kidney stone formation and growth inhibition based on a traditional medicine approach with \textit{Aquatica Lour (RAL)} herbal extracts. Kidney stone material systems were synthesized \textit{in vitro} using a simplified single diffusion gel growth technique. With the objective of revealing the mechanism of inhibition of calculi formation by \textit{RAL} extracts, samples prepared without the presence of extract, and with the presence of extract, were analyzed using Raman, photoluminescence, and XPS. The unexpected presence of Zn revealed by XPS in a sample prepared with \textit{RAL} provides an explanation for the inhibition process, and also explains the dramatic reflectance of incident light observed in attempts to obtain infrared transmission data. Raman data are consistent with the binding of the inhibitor to the oxygen of the kidney stone. Photoluminescence data corroborate with the other results to provide additional evidence of Zn-related inhibition. [Preview Abstract] |
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D1.00027: Spectroscopic analysis of WO$_{3}$ for sensor applications Jose Luis Enriquez, Felicia Manciu, William Durrer, Chintalapalle Ramana, Satya Gullapalli Samples of WO$_{3}$ thin films for use in gas sensors were grown using RF magnetron sputtering at a number of different substrate temperatures and Ar:O$_{2}$ pressure ratios. The structural properties of the samples were investigated, both experimentally and theoretically, with the goal of determining how variations in the above preparation parameters effect structural changes in the sensor materials. Such structural changes are of crucial importance to the question of improving the sensitivity, specificity, and durability of WO$_{3}$ based gas sensors. Experimental characterization was performed using the techniques of FT-IR, Raman, AFM, and XRD. The theoretical work involved software simulation techniques using Gaussian 09W$_{\mbox{{\textregistered}}.}$ [Preview Abstract] |
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D1.00028: Cylindrical Organic Solar Cells with Carbon Nanotube Charge Collectors Dante Zakhidov, Raymond Lou, Nav Ravi, Kamil Mielczarek, Alexander Cook Traditional organic photovoltaic devices (OPV) are built on a flat glass substrates coated by ITO. The maximum area covered by the solar cells is limited to a two dimensional plane. Moreover the light absorption is not maximized for a very thin photoactive layer. We suggest here a cylindrical design which has a vertical structure of optical fiber coated by OPV, with light incident from the side and from edge. The sunlight, entering via a smaller area is captured into optical fiber, which allows more sunlight to be absorbed by a cylindrical OPV overcoating with multiple reflections inside the optical fiber. Instead of using brittle ITO as a hole collecting layer in the cylindrical OPV, transparent sheets of multi-walled carbon nanotubes are applied. Their highly conductive nature and 3-D collection of carriers from the P3HT/PCBM photoactive layer allows for increased efficiency over a planar geometry while keeping the device transparent. Aluminum is used as the electron collecting layer and as a cylindrical mirror. \\[4pt] [1] Ulbricht, et.al, phys. stat. sol. (b) 243, No. 13, 3528 - 3532 (2006) / DOI 10.1002/pssb.200669181 [Preview Abstract] |
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D1.00029: Femtosecond Electron Diffraction and Shadow Imaging David McPherson Using femtosecond electron pulses as an imaging tool, we can probe ultrafast dynamics by taking snapshots at different time delays. By using femtosecond electron diffraction (FED), we can examine structural dynamics at the atomic level in real time, and study the structure-function correlation. Additionally, femtosecond electron shadow imaging (FESI) can explore the dynamics of laser induced plasmas off the surfaces of conductors, semiconductors, and insulators. [Preview Abstract] |
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D1.00030: Simple setup for hybrid coherent Raman microspectroscopy Kai Wang, Jiahui Peng, Dmitry Pestov, Marlan Scully, Alexei Sokolov We demonstrate a femtoseconcl-oscillator-based system for coherent anti-Stokes/Stokes Raman scattering microscopy, wherein impulsive Raman excitation is combined with narrowband, time-delayed, and therefore, background-free probing. We show that this simple technique can be used to identify chemicals. This work is supported by the Office of Naval Research, the Army Research Office, the Texas Advanced Research Program (Grant No. 010366-0001-2007), the National Science Foundation (Grants No. PHY 354897 and 722800), and the Robert A. Welch Foundation (Grants No. A-1261 and A-1547). [Preview Abstract] |
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D1.00031: Entanglement in Jaynes Cummings Model Samina Masood We study the entanglement in a two atoms two photon system using Schmidth decomposition.The results are compared with already existing results of entanglement of this system. With the detailed quantitative analysis of entanglement for such systems, we discuss the possible applications of these result. [Preview Abstract] |
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D1.00032: ABSTRACT WITHDRAWN |
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D1.00033: MBE Growth and Structural Characterization of Si-SiO$_{x}$-Si Films Ryan Cottier, Weerasinghe Priyantha, Nader Elmarhoumi, Ravi Droopad, Terry Golding Since the idea of a Si-SiO-Si superlattice was first proposed, two main groups have been associated with investigations of Si-SiO-Si superlattices - Tsu$^{i}$ and Lockwood$^{ii}$. Both groups have synthesized Si-SiO-Si structures on the technologically important Si (100) orientation. Lockwood has demonstrated visible light emission using photoluminescence (PL), and Tsu has demonstrated visible light emission using both electroluminescence and PL. The results of both groups show that the light emission can be tuned via quantum confinement within the Si quantum wells. We present the initial stages of an investigation into the synthesis and utility of Si-O layers as barriers. TEM and depth profiling XPS are presented as evidence of the crystalline growth of Si on ultrathin SiO$_{x}$ layers. \\[4pt] [1] R. Tsu, Nature \textbf{364}, 19 (1993).\\[0pt] [2] Z. H. Lu, D. J. Lockwood and J. M. Barlbeau, Nature \textbf{378}, 258(1995). [Preview Abstract] |
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