Bulletin of the American Physical Society
Fall 2014 Joint Meeting of the Texas Section of the APS, Texas Section of the AAPT, and Zone 13 of the Society of Physics Students
Volume 59, Number 12
Friday–Sunday, October 17–19, 2014; College Station, Texas
Session D1: Poster Session |
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Room: MIST and MPHY Foyer |
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D1.00001: Career Pathways for Undergraduate Physics Majors Toni Sauncy, Kendra Redmond, Roman Czujko There have been increasing calls to grow the size and diversity of the Science, Technology, Engineering, and Mathematics (STEM) workforce over the past decade. Undergraduate physics programs, with effective recruitment, retention and appropriate preparation of students, have the potential to add to the numbers of excellent members of the STEM workforce. However, many departments focus on preparing students for entry into advanced degree programs rather than on preparing the over 40{\%} who will enter the workforce. The obstacles for students and programs may arise from ignorance of both the nature of and the financial remuneration available for those equipped with a bachelor's degree in physics, as well as the broad scope of opportunities where a sound physics preparation can be of benefit. For faculty mentors, there may be an ignorance of the pathways to careers outside of academe. With support from the National Science Foundation, we set out to understand how physics departments can most effectively prepare their students for the STEM workforce and have developed a number of valuable resources for students, faculty mentors and department leaders. [Preview Abstract] |
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D1.00002: Internal stress, microscopic, and spectroscopic analysis in cadmium telluride grown by close-space sublimation Jessica Salazar, Stella Quinones, Aryzbe Diaz, William Durrer, Jose Valdez, Celia Garcia, Felicia Manciu Cadmium telluride remains one of the materials of interest in the fabrication of photovoltaic cells and infrared devices, mainly because of its suitable crystal structure as well as of its small, direct bandgap of 1.5 eV. Since development of such devices requires a high quality and low defect material, the goal of this study is to microscopically and spectroscopically examine the crystallinity of the material. This information is valuable if optimization of sample growth conditions is envisioned. Crystallinity of the samples was investigated by Fourier transform infrared absorption and Raman spectroscopies. The far-infrared transmission data show the presence of transverse optical and surface optical modes, the latter being direct evidence of confinement in such a material. [Preview Abstract] |
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D1.00003: Positron Annihilation Analysis of the Barnett Shale James Bufkin*, Joah Chun*, Helge Alsleben, C.A. Quarles Measurements are reported of positron annihilation lifetime and Doppler broadening parameters on 52 samples of Barnett Shale core selected from 196 samples ranging from depths of 6107 to 6402 feet. The Barnett Shale core was taken from EOG well Two-O-Five 2H located in Johnson county TX. The selected samples are dark clay-rich mudstone consisting of fine-grained clay minerals. The samples are varied in shape, typically a few inches long and about 1/2 inch in width and thickness, and are representative of the predominant facies in the core. X-ray fluorescence (XRF), petrographic analysis and geochemical analysis of total organic carbon (TOC) were already available for each of the selected samples. The Doppler broadening data determine two parameters, S (shape) and W (wing), which provide information on annihilation by valence or core electrons in the sample. Correlations of the lifetimes, intensities, the average lifetime and S and W parameters with TOC and XRF parameters are discussed. A linear model for TOC is also discussed. The observed correlations suggest that positron spectroscopy may be a useful tool in characterizing shale. *Participant in the summer 2014 TCU REU program in Physics and Astronomy funded by the National Science Foundation under grant PHY-1358770. [Preview Abstract] |
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D1.00004: Synthesis and Characterization of Thin Films Albert Chung, Connor Rigg, Andra Petrean Troncalli, Mikhail Kozlov In this study, we investigated the properties of gold thin films. We synthesized samples thinner than 50 nm by sputtering gold onto glass substrates. We subsequently characterized the electrical properties of the thin films between room temperature and 10 K. The optical properties were determined through spectroscopy measurements between 300 to 1,000 nm by recording transmission and reflection data and extracting the absorption coefficient of our samples. We consider a method of using the absorption coefficient to determine the thickness of thin films. [Preview Abstract] |
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D1.00005: One Step Microwave Dendrimer Synthesis of Monodisperse Size Controlled Tunable Noble Metal Nanoparticles using PEI Jewell Anne Hartman, Kim Hart, Bryce Brownfield, Kyle Culhane, Justin Case, Andrew Ballast, Ke Jiang, Anatoliy Pinchuk The size controlled synthesis of tunable, near monodisperse and stable noble metal Au and Ag nanoparticles with a narrow size distribution was achieved through the development of a parameter dependent one-step microwave assisted dendritic polymer stabilized technique. The one-step dendrimer assisted technique uses polyethelenimine (PEI) as both a reducing and stabilizing agent that encapsulates the nanoparticles for the synthesis of stable, size controlled noble metal Au and Ag nanoparticles. PEI was chosen to ensure stability of the nanoparticles produced. The effect of the parameters of time and temperature on the size of the nanoparticles produced was explored through the Box-Behnken design. Size control was achieved through a dual faceted process by modifying the mass ratio of metal salt to dendrimer or maintaining the mass ratio and modifying the temperature. Nanoparticle sizes were estimated using UV/Visible Absorption Spectroscopy, Dynamic Light Scattering, and Scanning Electron Microscopy. Mie theory calculations of the extinction spectra for an identical size nanoparticle are also presented. [Preview Abstract] |
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D1.00006: Analysis of CME and CIR driven storms based on observations made by the TWINS Mission Gunner Robison, Bianca Trigo, Amy Keesee, Jerry Carr Jr. Geomagnetic storms are categorized into two different groups' Coronal mass ejection, CME, and corotating interaction regions, CIR, driven storms. For CME driven storms there are intense and moderate storms based on their magnetic intensity, moderate is -78Dst anything below is categorized as an intense CME storm driver. This work will attempt to validate statements made by Keese 2013 by comparing previous two wide angle imaging neutral spectrometers, TWINS, data. Data was collected for an intense CME driven storm on September 26 2011 and a CIR driven storm on October 13 2012. [Preview Abstract] |
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D1.00007: Improvements in Drift Chamber 5 for the COMPASS II polarized Drell-Yan experiment James Mallon The COMPASS project is a fixed-target nuclear physics experiment at CERN which explores the internal structure of the proton, and~COMPASS II's polarized Drell-Yan experiments will be exploring the quark angular momentum contribution to the spin of the proton through Semi-Inclusive Deep Inelastic Scattering. As a part of this process, Drift Chamber 5 (DC5), based on DC4 built by CEA-Saclay, must be constructed to replace a faulty straw chamber. The 23 total frames of DC5 have an outside measurement of 2.94m by 2.54m, with the 8 anode frames having a total of 4616 approximately 2m-long wires, giving a detection region of 4.19m (squared) with a resolution of 200 microns. These wire planes are orientated with the x- and x'-frames in the vertical x-direction, the y- and y'-frames in the horizontal y-direction, the u- and u'- frames offset $+$10deg from the vertical x-direction, and the v- and v'-frames offset -10deg from the vertical x-direction, and are strung with 100 micron field wires and 20 micron sense wires. In order to solve left-right ambiguity, x', y', u', and v' are shifted by 4mm, or one drift cell. The x- and y-frames have 513 wires strung across them, with the field wires at 400g of tension, the sense wires at 55g on the x-frames, and 70g on the y-frames. The u- and v-frames will have 641 wires, with the field wires at 400g, and the sense wires at 55g. DC5 will also have an updated front end electronics setup, using a new pre-amplifier-discriminator chip, in order to allow the recording of more events per second. [Preview Abstract] |
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D1.00008: Optical V-Band Observations of Active Galactic Nuclei Taylor Hutchison, Raina Musso, Francis MacInnis Southwestern University astrophysics students participated in an international observing campaign to study twelve active galactic nuclei (AGN). As part of the project, the students measured optical V-band light variations of four targets within the range of the SU Fountainwood Observatory research telescope. Target images and a sample light curve of one target (NGC 5548) are presented. [Preview Abstract] |
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D1.00009: Mega-SH0ES: Near Infrared Cepheid P-L Relation from Milky Way to M101 Wenlong Yuan, Lucas Macri, Samantha Hoffmann, Adam Riess The Mega-SH0ES project aims to obtain accurate and precise distances to host galaxies of type Ia supernovae within 50 Mpc, as part of an effort to measure the Hubble constant with percent-level uncertainty. We studied the H-band P-L relation in M101 by combining archival ACS optical data with recent WFC3 near infrared data to derive the distance modulus to this galaxy. To assistant the ongoing HST parallax project, we are observing dozens of Milky Way Cepheids using ground-based telescope. This project will help to measure the assumption-free zero point of P-L relation and improve the distance ladder. We present the analysis and preliminary results for both projects. [Preview Abstract] |
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D1.00010: An Atmospheric Transmission Monitoring Camera for Dark Energy Survey Ting Li Traditional color and airmass corrections can typically achieve 0.02 mag precision in photometric observing conditions. A major limiting factor is the variability in atmospheric throughput, which changes on timescales of less than a night. We have built an Atmospheric Transmission Monitoring Camera (aTmCam), which consists of four telescopes and detectors each with a narrow-band filter that monitors the brightness of suitable standard stars. Each narrowband filter is selected to monitor a different wavelength region of the atmospheric transmission, including regions dominated by the precipitable water vapor and aerosol optical depth. The colors of the stars are measured by this multi narrow-band imager system simultaneously. The measured colors can be used to derive the atmospheric transmission of a site. We installed such system at the Cerro Tololo Inter-American Observatory and it started autonomous observation every night since Sept 2014. We derive hourly atmospheric transmission model from the observation; these atmospheric transmission model will be used to improve photometric precision of Dark Energy Survey and achieve 0.01 mag photometric precision. [Preview Abstract] |
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D1.00011: M-Dwarf Metallicity through Analysis of Binary Partners Daniel Nagasawa, Jennifer Marshall, Ting Li We present work on determining the metallicity of M-dwarfs through analysis of M-star containing binary pairs and discuss its potential use with regards to exoplanet host star population studies. It is notoriously difficult to directly measure the metallicity of M-dwarf stars via their spectra due to the complexity of their composition; by study of the spectra of M-dwarfs and their binary partners, a technique to determine the metallicity of M-dwarfs via spectra analysis can be developed. Assuming that the metallicity of two stars in a binary pair is similar, by studying the metal content of the more easily measured solar type star and correlating that to various spectra line indices in the accompanying M-dwarf, we can indirectly measure the metal content of the M-dwarf. We use both high and low resolution spectra of 50$+$ halo binary stars in the northern hemisphere collected at McDonald Observatory to perform this analysis. [Preview Abstract] |
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D1.00012: Spectra and Elliptic Flow of Hadrons in Nuclear Collisions In a Blast Wave Model With Shear Stress Zhidong Yang, Rainer J. Fries Collisions between heavy nuclei at high energies probe the properties of nuclear matter at high temperature and density. Hadrons observed at low transverse momenta ($<$ 2 Gev/c) at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) imply that the hot and dense matter created at those Colliders is close to thermal equilibrium at its kinetic freeze out. Hadron observables can be described well by fluid dynamics or blast wave parameterizations. Here we present a blast wave model that incorporates corrections from finite shear stress due to the inhomogeneities in the system. We also use this model as an input to calculate hadron spectra from quark recombination at higher transverse momenta ($>$ 2 GeV/c). [Preview Abstract] |
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D1.00013: Implementation and testing of a hypersurface finder for event-by-event (3+1)D hydrodynamics Steven Rose, Rainer Fries Hydrodynamic simulations of nuclear collisions can model the expansion and cooling of the fireball created in such collisions. Many applications require a fast and efficient algorithm to find and parameterize hypsersurfaces; e.g. the isothermal surface at the freeze-out temperature can be used to calculate a final distribution of particles in the collision via the Cooper-Frye procedure. An algorithm proposed by Pang, Wang, and Wang is evaluated and compared to standard algorithms in AZYHYDRO and Cornelius. [Preview Abstract] |
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D1.00014: Hydrocarbon based hybrid fusion-fission nuclear reactor Abul Hasanat Muhammad Jahanur Rahman Hydrocarbon resources can be used in more efficient ways through hybrid fission-fusion reactions. This offers longer supply of energy by using only a very small amount of fuel. Fusion reaction energy can be initiate using proton tunneling catalytic reactors that bypass the nuclear repulsion barrier at lower temperatures. This reactor uses mesosphore support made of pyroelectric and piezoelectric crystals. Pyroelectric convert the fusion temperature into electricity and piezoelectric control the diameter of porosity to determine diffusion and fusion reaction rate. This active catalyst is a quasi-crystal of fullerenes covered by a single layer of graphene. By providing a voltage difference across this catalyst, its conductivity can be changed. By using magnetic field, variable mass Dirac fermions (for example cooper electron-hole/phonon pairs) can be introduced within different conductive layers (heterogeneous topological layers or parallel quantum wells). Hydrocarbon by-products enter this catalyst from mesophores through microphores by carrier fluids which need to be supercritical and superfluid at input temperature and pressure. Zero mass Dirac fermions are very sensitive to the applied field by piezoelectric crystal supports which produce maximum charge carriers compared to other layers where electron pairs have less mass. The higher the momentum of these ions, the higher the mass of the Dirac fermions (electron). At the collision where Dirac electron mass higher than the effective electron, the probability of fusion increases due to an increase in gravitational pull between higher masses. This is controlled by resonance phonon frequency and the electric field. [Preview Abstract] |
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D1.00015: Experimental measurement of equation of state for isotropic suspension of nanoplates Abhijeet Shinde, Xuezhen Wang, Rodrigo Guerra, Zhengdong Cheng Liquid crystalline phases of disk suspensions are of importance in science and in industry for various applications such as conductive polymers, synthetic clay and semiconductors. We studied the self-assembly of highly anisotropic and narrowly polydispersed nanoplates of Zriconium Phosphate (ZrP). Here we report, measurement of the equation of state for isotropic phase. We generated the EOS by studying attenuation of x-ray in gravity sedimented suspension of exfoliated ZrP nanoplates. We compare our equation of state with the one obtained through simulation by others. [Preview Abstract] |
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D1.00016: Comparison of Hydration Free Energy from Orthogonal Space, Random Walk, Polarizable Force Field, and Bennett Acceptance Ratio Sara Cheng, Jayvee Abella, Pengyu Ren The Orthogonal Space Random Walk (OSRW) method has shown enhanced sampling efficiency in free energy calculations from previous studies. In this study, the implementation of OSRW in accordance with the polarizable AMOEBA force field in TINKER molecular software package is discussed and subsequently applied to the hydration free energy calculation of 20 small organic molecules, among which 15 are positively charged and 5 are neutral. The calculated hydration free energies of these molecules are compared with the results obtained from the Bennett Acceptance Ratio method using the same force field, and excellent agreement is obtained. The convergence and the efficiency of the OSRW are also discussed and compared with BAR. OSRW reduces the computational cost for hydration free energy calculation by almost five-fold. Combining enhanced sampling techniques such as OSRW with polarizable force fields is very promising for achieving both accuracy and efficiency in general free energy calculations. [Preview Abstract] |
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D1.00017: Electron dynamics in an inhomogeneous magnetic field Allen Kiester, Yuri Rostovtsev, Duncan Weathers We study the interactions of an electron with an inhomogeneous magnetic field using the time dependent Schrodinger equation. A simulation of an initially localized electron in an axially symmetric magnetic field of increasing intensity is presented. The electron initially is placed in a uniform magnetic field with components of momentum both transverse and longitudinal to that field. The simulation explores the energy exchange mechanism between on-axis and off-axis kinetic energies for a particle in a conservative system to describe magnetic reflection from a quantum mechanical perspective and the effect of reflection on the Landau levels. Analysis of the axial kinetic energy exchange, reflection, and transmission coefficients of a Gaussian wave-packet traveling from a uniform magnetic field into an inhomogeneous is presented. [Preview Abstract] |
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D1.00018: Study of the Medical Imaging of a Human Brain Jinho Kang, Soo Hwan Park, Ha Young Kyung In order to produce image domain from MRI, a complex computational process that requires an intensive analysis is involved. Often, the process of transformation from frequency domain to image domain requires time because Inverse Fourier Transformation takes every frequency points to determine the final output image. However, if a proper function is multiplied to K-space, it results in reduced domains of frequency, which will be used to determine output images. The purpose of the present research is to develop a more efficient low pass filter or filter function in order to increase the resolution of a brain MRI image, and at the same time, decrease the time required to produce the image. In~this paper, K-space was constructed from the MRI image of the human brain using the MATLAB software.~ Different proposed filters were applied on the full K-space in order to find the most efficient filter that can be used to produce best MRI image. [Preview Abstract] |
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D1.00019: Estakhr's Quantum Spacetime, Quantum Gravity as Expected Spacetime or Expection value of Spacetime Operators Ahmad Reza Estakhr Quantum Mechanics and General Relativity can be realized as a fully consistent theory. Spacetime is fundamentally discrete and not continuous. Spacetime Interval infact is expected value of time and position operators in the energy and momentum representation $ds^2=g_{\mu\nu}d\langle\hat {x}\rangle^{\mu} d\langle\hat {x}\rangle^{\nu}$ where the $ \langle\hat{x}\rangle^{\mu}$ is four-expected value vector. (that which means what we know as continuous spacetime infact is expected value of spacetime operators.) [Preview Abstract] |
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D1.00020: New possibilities for the efficiency enhancement of the high harmonic generation process in gas mixtures of Ne and H2 Muhammed Sayrac, Alexandre A. Kolomenski, Sunilkumar Anumula, Gamze Kaya, Necati Kaya, Hans A. Schuessler We have investigated how mixing of two gases (H$_{2}$ and Ne) with significantly different ionization potentials (IPs) modifies the high harmonic generation (HHG). We observed up to a 2.5 fold enhancement of HHG compared to pure H$_{2}$ and up to 3x10$^{3}$ enhancement compared to pure Ne at moderate laser intensities at the gas jet $\sim$ 1.5x10$^{14}$ W/cm$^{2}$ when the backing pressure of H$_{2}$ was fixed at 0.7 bar and the Ne pressure increased in steps of $\sim$ 0.4 bar up to $\sim$ 2.8 bar; the optimal Ne pressure was found to be about $\sim$ 0.5 -1 bar for different harmonics order. Initially, HHG in H$_{2}$ gas takes place due to its low IP, inducing excited states and facilitating ionization and HHG in the Ne gas with high IP [1]. For simulation of HHG in mixtures we employed a phenomenological model that took into account also the changes in the matching conditions, affecting the HHG process. Thus, mixing of gases with low and high ionization potentials opens up new possibilities for the efficiency enhancement of the HHG process. This work was supported by the Robert A. Welch Foundation Grant No. A1546 and the Qatar Foundation under the grant NPRP 5 - 994 - 1 -- 172. \\[4pt] [1] E. J. Takahashi et al. PRL 99, 053904 (2007). [Preview Abstract] |
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D1.00021: Wide-bandwidth solar energy harvest by using non-linear optics and fluid dynamic Abul Hasanat Muhammad Jahanur Rahman Existing solar technology converts only limited bandwidth of radiation into electricity due to Shockley-Queisser limit of the solar diodes. Rest get wasted by heating up the solar array or reflected back. This paper represent mechanical method of producing more electricity by absorbing wide-bandwidth of sun-rays. Thin organic solar panel sheet or perovskite cell is coated with nanoparticle for reflecting non-absorbed bandwidth of sun rays. This sheet can be bend into concave shape with different focal radius. By using solar cell mirror made of this panel with MPPT, a solar farm can be made that converts some of the solar energy into electricity and reflects rest of the solar bandwidth into one single focus location where a series of lenses and prisms are located. These lenses convert incoming-rays into collimated-Gaussian-beam, which goes through two multimode circular prisms with different refractive indexes in close loop waveguide for ring lasing pulse generation. This introduce Doppler broadening into these two anti-collinear beam across the cross-section of the laminar fluid flow, where center fluid layer has higher velocity than the boundary layer. So, higher frequencies come out near the circumference of one of the prism and lower frequencies come out from its center. And the other one has opposite effect. Two beams are tuned to be out of phase, which increases absorption by fluid. Similar to laser-cooling technique, all fluid atoms are excited to same virtual-energy-state in exchange of solar-power and fluid-momentum. This two photon absorption release narrow-bandwidth-high-intensity pulse that produce electricity in multi-channel-plates (MCP). [Preview Abstract] |
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D1.00022: Analyzing Hurricane Sandy Angelyn Convertino, Stephan Meyer, Rebbeca Edwards Post-tropical Storm Sandy underwent extratropical transition shortly before making landfall in southern New Jersey October 29 2012. Data from this system was compared with data from Hurricane Ike (2008) which represents a classic hurricane with a clear eye wall and symmetry after landfall. Storm Sandy collided with a low pressure system coming in from the north as the hurricane made landfall on the US East coast. This contributed to Storm Sandy acting as a non-typical hurricane when it made landfall. Time histories of wind speed and wind direction were generated from data provided by Texas Tech's StickNet probes for both storms. The NOAA Weather and Climate program were used to generate radar loops of reflectivity during the landfall for both storms; these loops were compared with time histories for both Ike and Sandy to identify a relationship between time series data and storm-scale features identified on radar. [Preview Abstract] |
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D1.00023: Sensitive Molecular Spectroscopy of Crude Oil and Well Gas Samples Yakup Boran, A.H.M Jahanur Rahman, Necati Kaya, James Strohaber, Alexandre Kolomenskii, Mahmood Amani, Vassilios Kelessidis, Hans Schuessler We have developed several sensitive laser and mass spectroscopy based analytical instruments for oil and gas analysis. Some of the approaches have the potential for near well applications. A portable quadrupole mass analyzer is capable of measuring hydrocarbons having hundreds of atomic mass units as well as to low mass targets, such as methane and carbon dioxide at ppm level concentrations. In addition, a small prototype handheld optical absorption sensor is available. Here we use the quadrupole mass analyzer and reflectron-type time-of-flight ion mass spectrometer. An important advantage of the reflectron apparatus is due to the use of femtosecond laser radiation. Such strong field radiation can defeat the dissociation rate of molecules allowing for intact molecular ions to be detected. Fragmentation free detection of target molecular ions facilitates interpreting the amount of a particular hydrocarbon molecule. We will present results on crude oil and well gas analysis, which yields information on wide range of hydrocarbon constitutes. Supported by the Qatar Foundation under grant NPRP 6-465-1-091 and the Robert A. Welch Foundation under grant No. A1546. [Preview Abstract] |
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D1.00024: Optimum conditions of high order harmonic generation with a gas jet Muhammed Sayrac, Alexandre A. Kolomenski, Sunilkumar Anumula, Yakup Boran, Gamze Kaya, Necati Kaya, Hans A. Schuessler We experimentally studied how high harmonic generation (HHG) with noble gases (argon, hydrogen) depends on pressure changes in the gas jet causing variations of the matching conditions and absorption. The pressure dependence of output of high harmonics was studied at moderate laser intensities $\sim$ 1.5x1014 W/cm$^{2}$ in the interaction region. To enable measurement over a wide range of pressures we employed differential pumping with an additional chamber ($\sim$ 20 cm$^{3}$ volume) enclosing the gas jet. By increasing the gas jet pressure up to the maximum of $\sim$ 3 bar with Ar, and $\sim$ 2.25 bar with H2, we observed the increase of the HHs output until pressure in the jet reached optimum of $\sim$ 0.5 bar for Ar, and $\sim$ 2 bar for H$_{2}$, beyond which the output started decreasing. [Preview Abstract] |
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D1.00025: Mechanical models for Electromagnetically induced transparency and quantum amplification by superradiant emission of radiation Steven Lanier, Yuri Rostovtsev Quantum amplification by superradiant emission of radiation is a new promising path to develop powerful sources of coherent radiation. It is related on the quantum spatial coherence excited in an atomic medium via interaction with laser radiation. We develop mechanical models that allow us to gain physical insights on how the spatial coherence build. Also we develop a mechanical model for electromagnetically induced transparency where the temporal coherence is excited in the atomic system and ``dark'' states are formed allowing light to be decoupled from the interaction with atomic system. [Preview Abstract] |
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D1.00026: Vibrational Spectra, Theoretical Calculations, and Two-Dimensional Potential Energy Surface for 2,4,7-trioxa(3.3.0)octane Hye Jin Chun, Niklas Meinander, Jaan Laane 2,4,7-Trioxa(3.3.0)octane (247TOO) is an unusual bicyclic molecule which can exist in four different conformational forms which are determined by which directions the two rings pucker. The vibrational assignments of 247TOO have been made based on its infrared and Raman spectra and theoretical density functional theory (DFT) calculations. The two ring-puckering motions (in-phase and out-of-phase) were observed in the Raman spectra of the liquid at 249 and 205 cm$^{-1}$ and these values correspond well to the DFT values of 247 and 198 cm$^{-1}$. \textit{Ab initio} calculations were utilized to calculate the structures and conformational energies for the four energy minima and the barriers to interconversion, and the data were utilized to generate a two-dimensional potential energy surface (PES) for the two ring-puckering motions. The resulting quantum state energies for this PES were then calculated in order to better understand the patterns that are produced when the PES has four energy minima at different energy values. The wavefunctions corresponding to the different quantum states were also calculated. For lower energy states these clearly correspond to just one of the wells in the PES. For higher energy states the probability is distributed over more than just one conformational form. [Preview Abstract] |
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D1.00027: Coherent population trapping on vibrational levels in stimulated Raman scattering Adam Vogt, Yuri Rostovtsev We study stimulated Raman scattering in molecular media. The role of rotational levels has been investigated by applying two strong laser fields in a two-photon resonance with a vibrational transition. It has been shown that the molecular vibrational coherence strongly depends on the effect of coherent population trapping for rotational levels. The obtained results are important for application of Raman spectroscopy to molecular detection for engineering, chemical, and biological applications. [Preview Abstract] |
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D1.00028: Filament propagation length of femtosecond pulses with Gaussian and Bessel-Gaussian modes Necati Kaya, Muhammed Sayrac, Gamze Kaya, Yakup Boran, James Strohaber, Alexandre Kolomenskii, Hans Schuessler We experimentally studied intense femtosecond pulse filamentation and propagation in water for Gaussian and Bessel-Gaussian incident beams. The transverse modes for incident laser pulses were created from a Gaussian beam of a Ti:sapphire laser system by using a computer generated hologram technique. We found that the length of the filament induced by the Bessel-Gaussian incident beam was longer than that for the Gaussian transverse mode under the conditions of the same peak intensity, pulse duration, and the size of the central part of the beam. To better understand the Bessel-Gaussian beam propagation, we performed a more detailed study of the filament length as a function of the number of radial modal lobes. The length increased with the number of lobes, implying that the radial modal lobes serve as an energy reservoir for the filaments formed by the central intensity peak. This work was supported by the Robert A. Welch Foundation Grant No. A1546 and the Qatar Foundation under the grant NPRP 6 - 465 - 1 - 091. [Preview Abstract] |
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D1.00029: Motion of Light on a Rotating Platform Charles Rogers, Richard Selvaggi This experiment uses a laser to determine the deflection of light in a rotating frame of reference. Our hypothesis asks what affect does circular motion have on the measured trajectory of photons? Does the trajectory of light measured in a rotating platform differ from that measured in a non-rotating platform? The apparatus design, operation, and measured results are presented. [Preview Abstract] |
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D1.00030: Molecular rotational constants measured with photoelectron ionization yield Gamze Kaya, Necati Kaya, Nathan Hart, Muhammed Sayrac, Sunil Anumula, James Strohaber, Alexandre Kolomenskii, Hans Schuessler We determined rotational constants of linear molecules by measuring the electron photoionization yields with the femtosecond pump-probe technique. By creating a rotational wave packet with linearly polarized pump pulse in N$_{2}$, O$_{2}$, CO$_{2}$, CO, and C$_{2}$H$_{2}$ molecules, we measured the temporal evolution of the photoelectron yield produced by the probe pulse with variable delay. The positions of the peaks and the rotational constants derived from the rotational revival periods of linear molecules are in good agreement with the literature values. This work was supported by the Robert A. Welch Foundation grant No. A1546 and the Qatar Foundation under the grant NPRP 5-994-1--172. [Preview Abstract] |
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D1.00031: Optical Properties of Permalloy Oxide Grown by reactive RF magnetron sputtering Yubo Cui, Fidele Twaqirayezu, Wilhelmus Geerts Permalloy oxide (PyO) is being studied to be applied in hematite based water splitting cells, shows promise to be applied in resistive random access memory devices, and has shown to increase the performance of spin valve hard disc reading heads. In this research, we investigated the optical properties of PyO thin films grown on quartz and Si/SiO$_{2}$ substrates. A series of different samples was made as a function of the deposition temperature (24$^{\circ}$C-600$^{\circ}$C). The PyO was deposited in an AJA Magnetron System using a gas flow of 10 sccm (20{\%} O2), and 240w RF power. The substrate was rotated at 60rpm during deposition. The optical properties were measured by a Woollam M2000 variable angle spectroscopic ellipsometer at 8 different angles (50$^{\circ}$ $\sim$ 85$^{\circ})$ from 200-1000 nm. The optical properties and the thickness were calculated in two steps. First a single peak Cody-Lorentz model was used to estimate the optical properties. This result was used as a start for a Bspline model to calculate the thickness and optical spectra of PyO. The MSE of the fits are below 4. The spectrum shows peaks around 2.4, 4, and 5 eV. The peaks of the spectra calculated from the thin films on Si/SiO2 are less sharp. The estimated thickness is in agreement with the sputter rate measured by a crystal thickness monitor. [Preview Abstract] |
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D1.00032: Measurement of the Absorption Coefficient of Biological Materials Using Integrating Cavity Ring-Down Spectroscopy Michael Cone, John Mason, Eleonora Figueroa, Brett Hokr, Joel Bixler, Cherry Castellanos, Jeffery Wigle, Gary Noojin, Benjamin Rockwell, Vladislav Yakovlev, Edward Fry An accurate knowledge of optical absorption coefficients for cells and their constituents is critical to the continued progression of biomedical procedures and modeling. However, the large scattering cross section associated with many biological materials presents a significant complication in accurately determining the optical properties of biological compounds through transmission-style experiments. Transmission-style experiments measure the attenuation coefficient by comparing the intensity of a light source before and after it passes through a desired medium. For highly scattering media, the light lost through scattering contributes significantly towards the attenuation coefficient. Using Integrating Ring-Down Spectroscopy (ICRDS), we are able to directly measure the absorption coefficient of any highly scattering media even in the presence of larger scattering cross sections and small absorptions. Using a fully-enclosed cylindrical cavity made from a new diffuse reflecting material, an isotropic field of illumination is created eliminating scattering losses in ring-down measurements. Our presentation discusses the technique in great deal and discusses experimental results using retinal pigment epithelium cells. [Preview Abstract] |
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