Bulletin of the American Physical Society
2016 Annual Meeting of the APS Mid-Atlantic Section
Volume 61, Number 16
Saturday–Sunday, October 15–16, 2016; Newark, Delaware
Session F1: Poster Session (To Be Set up 10:30 on Saturday) |
Hide Abstracts |
Room: Sharp Laboratory 100/120 |
|
F1.00001: Simulating x-ray diffraction of laser driven atomic diffusion Jacques Samaha, Matthew DeCamp Atomic diffusion in multi-metallic systems plays a very important role in the growth and development of novel metallic alloys and magnetic materials. Therefore, understanding the atomic scale dynamics that drive this diffusion is of fundamental importance. An x-ray diffraction simulation for the diffusion process in a metallic multi-layered system under picosecond laser excitation is presented. A simple one-dimensional atomic diffusion model was numerically simulated to describe the time-dependent concentration profile. X-ray diffraction patterns from the simulated concentration profiles patterns were then directly compared to experimental data, to reconstruct the concentration profile of laser driven diffusion. [Preview Abstract] |
|
F1.00002: Optical Absorption and Carrier Dynamics of Semiconductor Delafossites. Rishmali Sooriyagoda, Tess R. Senty, Barry Haycock, Jonathan Lekse, Christopher Matranga, Hong Wang, Gihan Panapitiya, Alan D. Bristow, James P. Lewis Delafossites semiconductor oxides (ABO$_{\mathrm{2}})$ are being considered for wide range of photovoltaic and photocatalytic applications. In ternary crystals the fundamental band gap is forbidden, whereas addition of second B site ion breaks inversion symmetry and allows the transition to occur. In this study, optical absorption, photoconductivity and transient absorption are used to investigate the carrier dynamics of delafossites CuGaO$_{\mathrm{2\thinspace }}$and related CuGa$_{\mathrm{1-x}}$Fe$_{\mathrm{x}}$O$_{\mathrm{2\thinspace }}$(with 0.00 $\le $ x $\le $ 0.05) alloys for potential applications. [Preview Abstract] |
|
F1.00003: Construction and Testing of a Scanning Fabry-Perot Interferometer Robin Depto, Wayne N Manrakhan Scanning Fabry-Perot interferometers (SFPI) are useful devices for determining the spectral characteristics of coherent light sources. Due to budget limitations, we constructed an inexpensive SFPI in the confocal arrangement with high enough precision for optical lab work. The SPFI's cavity length is adjusted via a voltage-controlled piezo transducer and the resulting changes in interference patterns are measured using an amplified photodetector. The output signal is then processed by either an oscilloscope or a spectrum analyzer. As a first test, the device was used to determine the longitudinal mode separation of a commercially available HeNe laser. An explanation of the design, a discussion of how components were selected, and the fabrication process will be presented. We will also present results that show our device performs as intended. [Preview Abstract] |
|
F1.00004: Stable Operation of a Laser Diode with High Coherency Jennifer E. McFarlane, John G. Bertelsen, Wayne N. Manrakhan High temporal coherence is required in numerous optical application such as interferometry, and holography. For laboratories with limited budgets, HeNe lasers provide excellent temporal coherency but their limited wavelengths restrict potential applications. Laser diodes are low cost, and available in multiple customizable wavelengths but their temporal coherency is adversely affected by the operating conditions. It would be of practical importance to determine which conditions offers the largest coherency. Thus the coherency of a single longitudinal mode laser diode was evaluated under different temperature and power (driving current) conditions. A simple contrast measurement of coherency was performed using a Michelson Interferometer. Our results indicate that the primary factor influencing coherency of the laser diode was temperature control. This temperature control appears to stabilize the mode structure of the laser. [Preview Abstract] |
|
F1.00005: Vampire Selfie: A Curious Case of an Apparently Absent Reflection Joshua Grossman, Charles Adler When an object is placed between a brushed metal plane and a parallel plane that is marked with lines perpendicular to the metal’s brushing, an interesting optical phenomenon occurs. A fairly clear reflection of the patterned plane is visible in the brushed metal, but the reflection of the object in between seems largely absent -- extremely spread out and diffuse. This 'Vampire Selfie' phenomenon is due to reflections from brushed steel surfaces such as elevator doors and bathroom stalls. Because of the irregular, predominantly vertical brushing, incoming light rays are scattered in the horizontal plane. This leads to reflections being spread horizontally. Any reflections with vertical features, such as faces, are blurred out, but if the background is featureless or has strong horizontal structure, it will seem unchanged. We will discuss the theory of the Vampire Selfie, examine other places where it can be seen, and develop a mathematical model for the point spread function of reflected rays in both the horizontal and vertical directions. We will also show results of experiments examining reflections from surfaces with different brushing finishes and compare them to theory. [Preview Abstract] |
|
F1.00006: External Focusing Effects on Filament Formation in Air Amelia Hankla, Matthew Edwards, Julia Mikhailova Self-focusing of high power laser beams occurs when non-linear focusing due to the optical Kerr effect overcomes diffraction. A threshold power for self-focusing (3.2 GW in air) can be estimated analytically; beam powers slightly above this threshold result in the formation of a single filament. This work characterizes the filamentary behavior of an 85-femtosecond, 3.9-mJ peak power laser beam in air, with particular emphasis on the beam’s critical power and conical emission, to validate computations using a solver for the non-paraxial unidirectional pulse propagation equation and to distinguish the roles of self-focusing and external-focusing. Simulations are extended to consider the effect of gas pressure on the development of multiple filaments in beams with powers up to 20 TW. [Preview Abstract] |
|
F1.00007: Development and Characterization of Dynamic Light Scattering Instrumentation to Determine Nanoparticle Size Samuel Harding, Jake Harding, Kate Holman, TJ Sebastian, Jeff Simpson Dynamic Light Scattering (DLS) provides a high-throughput and accurate measurement of particle sizes for monodisperse (MD) spherical nanoparticles (NPs). We report on the development and characterization of homebuilt DLS instrumentation to measure the size of MD NPs of gold and polystyrene. HeNe and Ar-ion lasers comprise the excitation sources for the scattering experiment. An avalanche photodiode detects scattered light and an autocorrelation card analyzes the signal to provide a measurement of the translational diffusion coefficient which, for MD and spherical particles, allows for the determination of NP radius. We have tested our apparatus using commercially produced gold NPs in the range 10nm to 200nm. After identifying temperature dependence of viscosity as a source of error, periodic ambient temperature measurements were used to produce dynamic values for viscosity and minimize uncertainty in NP size. DLS measurements will be compared to measurements obtained by Atomic Force Microscopy (AFM). K.H., T.J.S. and J.H. acknowledge support from Towson University. J.R.S. acknowledges support from NSF - CBET {\#}1236083. [Preview Abstract] |
|
F1.00008: Size control and large scale synthesis of Fe3O4 nanoparticles via step by step reaction Shirin Pourmiri, Frank Abel, Vasileios Tzitzios, George Hadjipanayis This work focuses on the synthesis and characterization of Fe3O4 nanoparticles by a simple chemical approach. The synthesis takes place in a oleylamine-oleic acid mixture using Fe(acac)3 as iron precursor under air atmosphere. The particle size was controlled following a step by step thermolytic approach; at each step the particles were investigated by TEM, XRD and magnetic measurements. The synthesized particles at 310 oC have an average size of 9.3 nm (1st step), 11.5 nm (2nd step), 13.6 nm (3rd step) and 16.5 nm (4th step) depending on the time and concentration at which the nanoparticles were synthesized. Magnetic measurements at room temperature show that the saturation magnetization of the particles increases with particle size from 54.0 emu/g in nanoparticles with 9.3 nm to 82.9 emu/g in the 16.5 nm particles. The smallest size particles show a higher slope in the high field M(H) data indicating surface spin canting. [Preview Abstract] |
|
F1.00009: Computational Calorimetry with the MARTINI Force Field Alexis Webb, Clement Arnarez, Edward Lyman The goal of this work is to validate the MARTINI simulation model for lipids by pinpointing the gel to fluid phase transition temperature of DPPC:cholesterol mixtures. A ``computational calorimetry'' analysis was applied to a large set of molecular dynamics simulation data ranging from 5{\%} to 30 mol {\%} cholesterol. Computational calorimetry mimics calorimetry as performed in laboratory experiments, obtaining the heat capacity as a function of temperature, and therefore admits a direct comparison to a large body of experimental literature on the same mixtures. Other observables such as the area per lipid, the thickness of the bilayer, and the ordering of the lipid tails are also reported. The simulated results agree qualitatively with the experimental results, including the shift in transition temperature with increasing cholesterol content. [Preview Abstract] |
|
F1.00010: Effects of Gold Nanoparticles on Lipid Packing and Membrane Pore Formation Anupama Bhat, Lance Edwards, Xiao Fu, Dillon Badman, Samuel Huo, Albert Jin, Qi Lu Gold nanoparticles (AuNPs) have been increasingly integrated in biological systems, making it imperative to understand their interactions with cell membranes. Herein, liposomes composed of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) as a model membrane were treated with citrate stabilized AuNPs of various sizes and concentrations. The fluorescence shifts of Laurdan probe revealed that AuNPs in general made liposomes more fluidic. The increased fluidity leads to an increased surface area which makes liposome less circular, as further confirmed in fluorescence images. The localized stress in lipids induced by electrostatically adsorbed AuNPs was hypothesized to cause the dominant long-range effect of fluidization of unbound lipid membranes. A secondary effect of the AuNP-induced lateral pressure is the formation of pores, which was observed in AFM images. What we found in this study offers a new approach of modulating the stiffness of lipid membranes: by adsorption of AuNPs, lipids at the binding sites are stiffened whereas lipids afar are fluidized. Understanding the factors that modulate lipid packing is important for the discovery of new therapeutic methods for diseases that are linked to membrane integrity such as high blood pressure and cancer metastasis. [Preview Abstract] |
|
F1.00011: Iron biomineral core structure of in vitro reconstituted human ferritins overexpressed in E-coli: A M\"{o}ssbauer investigation. Steve Kim, Fadi Bou-Abdallah, Paolo Arosio, Arthur Viescas, Georgia Papaefthymiou Ferritin is a protein responsible for the storage of iron in living organisms. Ferritin is composed of a protein shell and an iron biomineral core consisting of ferrihydrite. M\"{o}ssbauer spectroscopy can be used to find the oxidation state and coordination symmetry of the iron ions and overall electronic and magnetic properties of the core. Using this spectroscopic technique we have tested the core-shell model of ferritin on engineered proteins overexpress in \textit{E. coli}, containing various ratios of heavy (H) and light (L) chains. The core-shell model states that the biomineral core is composed of a magnetically ordered inner core and an outer magnetically disordered shell. Due to its nanometric size (d\textasciitilde 7 nm) the ferritin core is superparamagnetic at room temperature, which means that the magnetic moments of the iron ions are constantly flipping in direction. Our study probes the structure and superparamagnetic properties of the core and their dependence on the nature of the protein shell. Preliminary results seem to validate the core-shell model of the ferritin core and shed some light on its dependence on the H/L chain ratios, $i.e$., the number of ferroxidase centers on the protein. [Preview Abstract] |
|
F1.00012: Thermodynamic Analysis of Compounds in the Antiaging Components and the Reactive Oxygen Species(ROS) Jong Ha Lee, Jaeyeon Park, Nikita Patel This research paper uses computational analysis to figure out the thermodynamic stability of various compounds used in anti-aging antioxidant. Primary method to determine such stability include finding the optimal shape based on stereochemistry. Reactive Oxidation Species (ROS) causes a shift in cell structure as it allows highly reactive chemicals to bond to the nucleus of cells. The results of such changes lead to cell aging. In this paper, we investigate the safety and stability of the components used in vitamin E such as α-, β-, γ-, and δ-tocopherol and α-, β-, γ-, and δ-tocotrienol, which reduce the level of ROS of our body cells. This is achieved via studying the stereochemistry of the compounds by using computational thermodynamic analysis and force optimizations. Molecules that we examined include a few isomers of fullerenes. Density Functional Theory (DFT), a computational chemistry technique, is used in order to model the electron properties of the compound. The research validates that chemical compounds that have lower optimization energy are more safe and effective to be used in anti-aging products. [Preview Abstract] |
|
F1.00013: Thermodynamic Analysis of Compounds in Sunscreen and the Cancer-Causing Reactive Oxygen Species (ROS) Richard Kyung, Johyun Lee This research paper uses computational analysis to determine the physical and thermodynamic stability of various compounds used in sunscreen. The two primary methods to determine such stability include finding the optimal shape of the materials and computing the measures of oxidizing ability. Reactive Oxidation Species (ROS) causes a harmful shift in cell structure as it allows highly reactive chemicals to bond to the nucleus of cells. The results of such changes that occur within cells are mutated cells, which can be the leading cause of cancer. In this paper, we investigate the safety of the components used in sunscreens and the possibility of replacing existing chemical compounds to reduce the level of ROS. This is achieved via studying the shape and reactivity of the structures by using computational thermodynamic analysis and force optimizations. Molecules that we examined include oxybenzone, octocrylene, metal oxides, and fullerenes. Density Functional Theory (DFT), a computational chemistry technique, is used in order to model the electron properties of the compound. The results of the computational analysis validate that oxide chemical compounds and fullerene derivatives, which have lower optimzation energy, are more safe and effective to be used in suncreen. [Preview Abstract] |
|
F1.00014: Wet Etching of Laser Ablated Si to Form Micro/Nano-Structured Porous Membranes Shannon Knight, Kurt Kolasinski Nd:YAG laser irradiation (160 mJ at 532 nm in 6--7 ns pulses) transforms Si(100) by the production of conical pillars (tens of micrometer length, spacing several micrometer). Flowing Ar maintains a reducing atmosphere. We varied the pressure (1--300 mbar) to control redeposition and growth of material out of the laser plume onto the substrate. Laser ablated Si was anisotropically etched in 40 wt{\%} KOH at 80 \textdegree C. At short etch times defective material was removed to reveal the underlying crystal planes. Pillars, crystalline at their core, were sharpened to extremely high aspect ratios (as small at 10 nm tips on 50 \textmu m tall pillars). At longer etch times, etching along crystallographically defined directions lead to formation of oriented rectangular pores with side length \textasciitilde 5 \textmu m. Stain etching of this structure in V$_{\mathrm{2}}$O$_{\mathrm{5}}+$HF(aq) lead to the formation of nanocrystalline, nanoporous Si walls that exhibit visible photoluminescence. Thus, we make hierarchical porous materials constructed of crystallographically ordered \textmu m pores, the walls of which we chose to be solid or porosified on the nanoscale. We are currently optimizing the process such that the macropores extend all the way through the substrate. [Preview Abstract] |
|
F1.00015: Metal Organic Frameworks(MOFs) as a Renewable Green Energy June Pyo Suh, Richard Kyung Renewable green energy and eco-friendly technology have become pressing fields in research amidst the 21st century energy and environmental crisis, and Metal Organic Framework (MOF) has emerged as a potential solution to many of these problems. Composed of inorganic metal and organic carbon linkers, MOFs’ porosity and subsequent gas adsorptive property has made MOF a prospective candidate for storing and filtering atmospheric pollutants, gases that accelerate global warming, and alternative energy sources. In this paper, Density Functional Theory (DFT), a computational chemistry, has been employed to figure out the stability and thermodynamics of different structures of MOFs, and to model the electron properties of the compound. With Avogadro, a program that allows performing such computations for a compound, this paper demonstrates the optimized geometry energy levels and fully determines the theoretical values of the structure’s atomic properties. By doing such analysis, this research seeks to allow scientists and engineers to develop more efficient ways to check global warming and air pollution, to store and use energy, and to provide a refreshing driving force to the renewable, green energy research. [Preview Abstract] |
|
F1.00016: Enhancements of Catalytic Behavior Using Metal Oxides Jihyun Hwang, Haeun Lim, Jonathan Kim Many studies have shown that the enhancements of catalytic behavior were produced due to the role of the oxide-metal interface, which plays a crucial role in catalytic process industry. Increase of surface oxide-metal interface increases the ability of individual molecules to attract each other and causes weaker intermolecular force. The properties of an atom such as its momentum, position, and energy level are defined by the electron structure, and the catalytic efficiency of a compound depends on its electron structure as well. This project aims to determine the catalyzing ability of Rhenium compounds using a computational chemistry method, also using programs such as Avogadro and Chemcraft, in an effort to discover the optimal method and to compute the measures of catalytic ability. Density Functional Theory (DFT), a computational chemistry, is used in order to model the electron properties of the compound. Gamess is a program that allows performing such computations for a compound. It takes an input file of a defined format and converts it into an output describing the molecule and the reaction. This program shows the optimized geometry energy levels and fully determines the theoretical values of the structure’s atomic properties. [Preview Abstract] |
|
F1.00017: Rotational and Translational Diffusion of Low Molecular Weight Nanoprobes in Ficoll Solutions. Elton Jhamba, Zakaria M'Rah, Hacene Boukari We combine fluorescence spectroscopy, fluorescence correlation spectroscopy, and fluorescence anisotropy techniques to probe changes of the fluorescence property, the translational diffusion, and the rotational diffusion of Alexa488 fluorophores (MW$\approx $885 Da) mixed in non-fluorescent hence ``invisible'' aqueous Ficoll (MW$\approx $70 kDa) solutions under thermal fluctuations. The fluorescence correlation functions can be readily fit with the expression describing normal particle diffusion. Changes of the diffusion coefficients cannot be accounted for by the corresponding changes of the bulk viscosity of the Ficoll solutions as would be suggested by the Stokes-Einstein relations for both diffusion coefficients. We analyzed the data with the entropic model proposed by de-Gennes and his collaborators, and fit each set of diffusion data with a stretched exponential [exp(-$\alpha $c$^{n})$] with n being related to the quality of the solvent. The fits yield n-value close to one, suggesting a theta-like behavior of the host Ficoll-water system. However, the $\alpha $-value for translation is larger than that of rotation, indicating dissimilar local entropic effects on the rotation and translation. [Preview Abstract] |
|
F1.00018: Polarization-dependent interference between dipole moments of a resonantly excited quantum dot Disheng Chen, Gary Lander, Glenn Solomon, Edward Flagg An unconventional line-shape that depends on the detection polarization is observed in the resonant photoluminescence excitation (RPLE) spectrum of a neutral InGaAs quantum dot. We investigate this phenomenon by performing polarization-dependent RPLE measurements and simulating the measured spectra with a 3-level quantum model. This analysis enables us to extract the coherence between the two exciton states from the measured spectra. The good agreement between the data and model indicates that interference between the fine structure split exciton states is the key to understanding this phenomenon. There are only two necessary conditions to observe this interference: non-degenerate states, with orthogonal dipole moments. Since these conditions are relatively unrestrictive, such a situation may occur in many solid state systems, for example, quantum dots, NV centers in diamond, and possibly defect-bound states in 2-D materials. [Preview Abstract] |
|
F1.00019: Enhanced Superconductivity in Aluminum-based Metamaterials Christopher Jensen, William Zimmerman, Joseph Prestigiacomo, M.S. Osofsky, Heungsoo Kim, Nabil Bassim, Zhen Xing, M. M. Qazilbash, Igor Smolyaninov, Vera Smolyaninova Recent experiments have shown the viability of the metamaterial approach to dielectric response engineering for enhancing the transition temperature, Tc, of a superconductor. We demonstrate the use of Al2O3-coated aluminium nanoparticles to form the recently proposed epsilon near zero (ENZ) core-shell metamaterial superconductor with a Tc that is three times that of pure aluminium [1]. We have also demonstrated that an Al/Al2O3 hyperbolic metamaterial geometry is capable of a similar Tc enhancement, while having superior transport and magnetic properties compared to the core-shell metamaterial superconductors [2]. These results open up numerous new possibilities of considerable Tc increase in other simple superconductors. [1]. V.N. Smolyaninova, K. Zander, T. Gresock, C. Jensen, J.C. Prestigiacomo, M.S. Osofsky, and I.I. Smolyaninov, Scientific Reports 5, 15777 (2015). [2]. V.N. Smolyaninova, C. Jensen, W. Zimmerman, J.C. Prestigiacomo, M.S. Osofsky, H. Kim, N. Bassim, Z. Xing, M.M. Qazilbash, and I.I. Smolyaninov, Scientific Reports (in press), (2016). [Preview Abstract] |
|
F1.00020: Geometrically frustrated double perovskite synthesis and structural characterization William Martin, Jefferson Toro, Demetrios Papakostas, Jeremy P. Carlo Geometric frustration occurs when magnetic order is inhibited by the arrangement of ions in a material. Typically associated with triangular or tetrahedral coordination of moments favoring antiparallel alignment, frustration results in rich magnetic phase diagrams, and is thus of interest for elucidating the development of magnetism in materials.~Double perovskites A$_{2}$BB'O$_{6}$ potentially exhibit frustration, and the chemical versatility of the perovskite structure enables systematic studies of frustration physics across a wide array of compounds. We report structural characterization of compounds based on the 4d$^{1}$ Mo$^{5+}$ ion synthesized via solid state methods. We find that Ba$_{2}$YbMoO$_{6}$ and Ba$_{2}$LuMoO$_{6}$ crystallize in a simple cubic perovskite structure, whereas Sr$_{2}$YMoO$_{6\, }$exhibits a monoclinic structure, consistent with prior results. Syntheses of Sr$_{2}$GaMoO$_{6}$, Ca$_{2}$AlMoO$_{6}$, Sr$_{2}$ScMoO$_{6}$, Ba$_{2}$InMoO$_{6}$, Sr$_{2}$AlMoO$_{6}$, Ba$_{2}$ScMoO$_{6}$, Ba$_{2}$GaMoO$_{6}$, and Ba$_{2}$AlMoO$_{6}$ were attempted, although the desired phases were not produced. Possible causes include loss or non-reactivity of precursors, and phase diagrams favoring non-perovskite structures. [Preview Abstract] |
|
F1.00021: Effective Theory for Domain Wall Melting Ryan Cadigan, Deepak Iyer A variety of recent studies have shed light on the far from equilibrium behavior of quantum systems. Research suggests that this field of study may produce unfamiliar dynamical realizations of quantum states. It has been shown that in some cases a time evolving quantum state is equivalent to the ground state of an “effective” Hamiltonian where the time enters as a parameter. Here, we study the dynamical behavior of noninteracting fermions in a one-dimensional lattice starting from a “domain wall” initial state. As the system equilibrates, we look at the distribution of particles as well as correlations between particles in the system. We then compare the actual time evolving state of the system to the ground state of the effective Hamiltonian to study how long this description is valid, and when and where it breaks down using the trace distance between the full density matrices of the two systems. We generally expect that the description is valid in a given region as long as the boundary effects do not propagate into the region. [Preview Abstract] |
|
F1.00022: Planck Time Interval which a Photon Processes a Package of Information for Travelling a Planck Length as the Unit of Information in Planck Units Hassan Gholibeigian In the author's vision, there is a dimension of information in addition of space-time's dimensions in the universe which all particles and space-time permanently are floating in it and getting packages of new information for processing. Communication of information with fundamental particles (strings) as a ``fundamental symmetry'' in the nature has a vital role in leading all phenomena. So, a photon needs to get a package of complete information including law about its quantum state for processing and selecting its next step. Its next step which is moving a Planck length, takes a Planck time. A package of information including the new quantum state of the photon should always be available for it during a Planck time. My proposed formula for calculation of the number of packages of information ($I)$ is: $I=t_{P}^{-1} .\tau $ in which $t_{P} $ is Planck time and $\tau $ is lifetime of fundamental particle (string) per second. So a photon processes $1.8\times 10^{43}$ packages of information for finding its path in a second. The processed information is carried by the photon to store in history of the universe. Therefore, I propose unit of one ``Package of information'' for each Planck time to the APS as a new unit in Planck units. [Preview Abstract] |
|
F1.00023: Observing the Antarctic Ozone Layer with IceCube's High Energy Cosmic Ray Muon Bundles Jonathan Clifford, Serap Tilav, Takao Kuwabara IceCube is a high energy neutrino telescope located at the South Pole, consisting of a cosmic ray air shower array on the surface and a neutrino detector in the Antarctic ice at depths of 1450-2450m. While the in-ice sensors look for rare upgoing astrophysical neutrinos as signal, downgoing muon bundles with energies above 400 GeV are able to penetrate and trigger the detector at a 2.1kHz rate. These downgoing muons are created by cosmic ray interactions in the stratosphere and we observe both seasonal modulation in their rate and short term correlations with the stratospheric temperatures. We find that the observed muon rate best correlates with the temperature variations in the Antarctic ozone layer. [Preview Abstract] |
|
F1.00024: ANITA Neutrino Detector Matthew Collins, Victor Arriaza, Peng Cao The main goal of the ANITA program is to detect cosmogenic neutrinos, with energies \textasciitilde 1019 eV, produced through the interaction of ultra-high energy cosmic rays (\textasciitilde 1020 eV) with the cosmic microwave background. The neutrinos are detected by observing ``Askaryan'' radiation produced as a result of neutrino interactions in the Antarctic ice sheet. During the flight, data from the ANITA payload is constantly being transmitted to the ground and stored in SQL databases for monitoring data acquisition and flight operations. For the ANITA-IV mission this data will be made visible to project scientists through a newly designed web based data distribution system. This involves a series of challenges, from retrieving the data to designing the web layout. The application is being run through the Python package Flask on the server side, but utilizes HTML5 and JavaScript on the client side. These two languages permit the use of open source graphical and statistical libraries and allow us to make meaningful changes to the layout and functionality of the webpage. Finally, the collaborative effort is being achieved through the use of the websites GitHub for the means of sharing code and Heroku for the purpose of live testing the website. [Preview Abstract] |
|
F1.00025: Electronic behavior of Coumarin labelled quantum sized Au clusters. Angela Meola, Viraj Thanthirige, Keith Reber, Mary Sajini Devadas Magic number gold clusters are at the forefront of research owing to their characteristic size dependent optical and electrochemical properties. Of recent interest is their use as biological imaging agents due to their near-IR luminescence (whose wavelength of emission is ligand dependent). Magic number Au$_{\mathrm{25}}$L$_{\mathrm{18}}$, and Au$_{\mathrm{144}}$L$_{\mathrm{60\thinspace }}$clusters were synthesized using a one phase method with L $=$ hexanethiol or dodecanthiol as a stabilizing ligand. The electronic transition states of each particle was observed through UV-Vis, steady state fluorescence, and electrochemical analysis. The clusters were characterized through observation of documented HOMO/LUMO gap using both optical and electrochemical techniques. Au$_{\mathrm{144}}$-clusters indicated quantized double layer charge upon electrochemical analysis. Steady state fluorescence measurements indicates quenching. Transmission electron microscopy was employed to determine particle size and dispersity. The MPCs (Mono Protected Clusters) with the hexanethiol stabilizing ligand were then labeled with a coumarin dye via directed ligand exchange. The products of the exchange reaction were then compared with the MPC made from the coumarin ligand. The details of the synthesis, characterization and two-photon cross-sections of these clusters will be presented. [Preview Abstract] |
|
F1.00026: Surface metallurgical study of corrosion and surface residuals due to cleansing agents on four collector coins scanned via XRD, wavelength-dispersive XRF, and SEM fifty years after cleaning Anne Tabor-Morris, Marilyn Dillon Surface metallurgical techniques were used on several coins struck at dates ranging from antiquity to the late 1800s. Coins were of the same trove, likely a forgotten buried family treasure, unearthed in the 1960s. The prospectors heavily cleaned the coins using various agents, then stored them with only occasional handling, allowing the coins to re-oxidize over a period of nearly 50 years. The purpose of this study is to report the results of surface analysis via X-Ray Diffraction (XRD), wavelength-dispersive X-ray Fluorescence (XRF), and Scanning Electron Microscopy (SEM) to examine corrosion and surprising surface residuals of such cleaning, years later. [Preview Abstract] |
|
F1.00027: Observational Study of the Nantucket Sound's Marine Atmosphere Boundary Layer with application of Monin-Obukhov Similarity Theory and Critical Layer Theory Robert Jaquette Long term atmospheric data collected from the Cape Wind Meteorological Tower has been studied to further our understanding of the turbulent structure of Stable Marine Atmosphere Boundary Layers. Following the Monin-Obukhov Similarity Theory, we have normalized and plotted these results from the collected data in order to study the dependence of our data on the stability parameter $(\zeta = Z/L)$ as concerns the concept of "z-less" stratification. Results from this study suggest that only the non-dimensional standard deviation of the air temperature and dissipation of the Turbulent Kinetic Energy follow trends of "z-less" stratification in very stable conditions. Whereas, on the other hand, the standard deviation for each wind component and dissipation of the temperature variance deviate from this concept, suggesting that "z-less" stratification is not applicable in general. Additional work exploring Miles Critical Layer Theory is underway with the intent to consider wave affects on the turbulence, which are not considered in Monin-Obukhov Similarity Theory. However, due to naturally short transitional waves produced from the shallow water depths around the tower (6.6 m), studying the wind components for coherence is complicated by the nondispersive nature of shallow water waves. [Preview Abstract] |
|
F1.00028: Verification Studies for the Noh Problem using Non-ideal Equations of State and Finite Strength Shocks Sarah Burnett, Kevin Honnell, Scott Ramsey, Robert Singleton Jr. The Noh verification test problem is extended beyond the commonly studied ideal gamma-law gas to more realistic equations of state (EOS): including the stiff gas, the Nobel-Abel gas, and the Carnahan-Starling EOS for hard sphere fluids. Self-similarity methods are used to solve the Euler compressible flow equations, which in combination with the Rankine-Hugoniot jump conditions, provide a tractable general solution. In the planar case, this solution can be applied to any equation of state and does not necessarily have to exhibit strong shocks; for cylindrical and spherical geometries it is necessary that the analysis be restricted to strong shocks. The exact solutions are compared with numerical results obtained from the Lagrangian hydrocode FLAG. As the shock moves further from the wall, the simulation errors decreased in magnitude both at the origin and at the shock and also spread more broadly about these points. The overall spatial convergence rate remained first order. LA-UR-16-26903 [Preview Abstract] |
|
F1.00029: A Colloidal Lithography and Catalyzed Growth Approach to Semiconducting Nanowire Sensors Joshua M. Carlson, Kevin Mack-Fisher, Kurt W. Kolasinski, Shawn H. Pfeil Semiconducting nanowires present an attractive candidate for biological sensors due to their large area to volume ratios, and corresponding large change in optical and electrical properties upon ligand binding. Here we present a fabrication scheme and preliminary data on the production of ordered arrays of nanowires, on substrates suitable for integration into optical devices, via a combination of colloidal lithography and catalyzed growth. Targeted materials include both oxides and sulfides of Co, Fe, Cu and Zn. This protocol has the advantage of creating nano-patterned devices without the need for e-beam or DUV lithography. Furthermore, by growing nanowires on optically distinguishable seeds, this protocol has the potential to allow the measurement of both the properties of individual nanowires and the ensemble. [Preview Abstract] |
|
F1.00030: Sacrificial Nanoimprint Lithography as a Scalable Approach to Porous Polymer Membranes Lin Lei, Imrhankhan Shajahan, Devin Shaffer, Edwin Chan, Jonathan Singer The use of sacrificial templates for nanoimprint greatly expands the capability of the method particularly with regards to maximum aspect ratio. Here, we demonstrate the ability for the sacrificial imprint method using ZnO nanorods to produce porous polymer membranes. It is established that such structures can be grown cheaply and quickly with tunable morphologies on a wide variety of substrates, which we exploit to generate the nanoscale imprint features through this bottom-up approach. In this technique, rods grown on one substrate are transferred to a film through a combination of nanoimprint and nanotransfer printing. Since the oxide materials are sacrificial and regrowable, issues of detachment are mitigated. Through etching the oxide, we are left with a dense array of pores in the transferred material. By using a supported polymer film thinner than the oxide rods, these films become perforated membranes. In this study, we employ the technique to produce films with sub-100 nm pores and pore aspect ratios exceeding 5 for the application of support layers for osmosis membranes. Due to the flexibility of the sacrificial imprint paradigm, films produced in this way are highly scalable to large areas or even roll-to-roll processing. [Preview Abstract] |
|
F1.00031: Aluminum Nitride Thin Films for Pyroelectric Detection Nicholas Calvano, Andrew Voshell, Keesean Braithwaite, Philip Chrostoski, Dennis Prather, Mukti Rana A pyroelectric detector is a class of thermal detector for which there is a change in spontaneous polarization. Absorption of infrared radiation in the sensing layer of pyroelectric detector causes a change in temperature and hence changes in spontaneous polarization which finally generates a voltage. The objective of this work is to deposit and characterize thin films of ${Al}_{x}N_{y}$ for using them as pyroelectric material. Capacitors of ${Al}_{x}N_{y}$ thin films with Au electrodes were designed using Intellisuite software. Capacitors of various sizes were fabricated. The diameter of the electrodes for capacitor was varied between 400 $\mu $m to 1100 $\mu $m with 100 $\mu $m increment. The distances between two electrodes were varied between 400 $\mu $m to 1100 $\mu $m with 100 $\mu $m increment as well. On a 3 inch diameter cleaned quartz wafer, 20 nm thick Ti adhesion layer was deposited followed by a 100 nm thick Au layer. On top of this Au layer, 100 nm ${Al}_{x}N_{y}$ thin film was deposited. Finally, 100 nm thick Au layer was deposited and lifted off by conventional photo lithography to form the electrodes of capacitors. All the layers were deposited by radio frequency sputtering at room temperature. Morphology and electro-optical properties for ${Al}_{x}N_{y}$ thin films are now being investigated in the laboratory. [Preview Abstract] |
|
F1.00032: Point Contact Spectroscopy of Iron PNICTIDE: Effects of Sample Carrier Design and Fritting on the Conductivity and Observable Energy Gaps of Ba$_{\mathrm{(1-x)}}$K$_{\mathrm{x}}$Fe$_{\mathrm{2}}$As$_{\mathrm{2}}$. Luke Conover, Sam Biche, Oberon Wackwitz, Joseph Lambert, Roberto Ramos Multi-band superconductors, such as the iron pnictides, can exhibit multiple energy gaps depending on the crystal growth conditions and on which tunneling directions are made accessible by the sample fabrication process. The gaps are often anisotropic with respect to the crystal lattice, with some gaps predominantly conducting parallel or perpendicular to the c-axis of the lattice.~ Using point contact spectroscopy (PCS), it is possible to measure the energy gaps along the axes simultaneously at low temperatures.~ We describe our progress in measuring the energy gaps of iron pnictide single crystals (K-doped Ba-based 122 family) using PCS, discussing the effects of our soft point contact carrier design, contact size (effective resistance through the junction) and electrically tuning the point contact region using fritting techniques. [Preview Abstract] |
|
F1.00033: Design and Testing by Undergraduates of a Solenoidal Magnet to Field-Modulate the Critical Current of an all-MgB2 Josephson Junction Oberon Wackwitz, Luke Conover, Joseph Lambert, Roberto Ramos We describe the process of designing, building, and characterization, by undergraduates, of a solenoidal magnet to modulate the critical current of all-MgB2 thin film Josephson junctions. Using the magnetic field expression of a solenoid of finite length, the design parameters were determined and used to fabricate several prototypes of a magnet. A three-axis magnetometer was then used to map the field near the solenoid's geometric center, and the field was calibrated as a function of current. The solenoid was then mounted on a cryocooler shield and centered about an all-MgB2 thin film Josephson junction to be cooled down to 2 degrees Kelvin. We discuss the resulting magnetic field modulation of the junction's critical current and the estimated junction geometric area, as well as its impact on our current energy gap measurements in MgB2. [Preview Abstract] |
|
F1.00034: Mechanical Analysis of the Rail under Axial Loading and Thermal Stress Richard Kyung, Seung Won Park High compressive and tensile forces can be created in rails due to thermal expansion of the rail material. Such a compressive force, together with dynamic loads of the train applied to the track, can lead to dangerous track buckling. To minimize this effect, rails should be adjusted to eliminate or minimize compressive forces and longitudinal thermal load at an intermediate temperature. This paper presents how the temperature changing from a neutral temperature results in longitudinal force and how thermal expansion and contraction leads to variations in the strain, which cause longitudinal stress in rails. The longitudinal normal force in the rail resulting from a temperature change is also determined. In addition, longitudinal stress due to thermal expansion and contraction in rails that are restricted in their longitudinal movement or confined at the ends is calculated. To examine the effect of static loads applied on the rail, the railroad model is divided into 15 sections. Then, the pressure of each section is calculated for the rail type A and B. The results show that the pressure exerted on the section increases, remains constant, and then decreases, as the section moves from the top to the bottom. [Preview Abstract] |
|
F1.00035: Frequency Analysis of the Cello Using Acoustics and Physical Simulations Junghoon Han, Hyun Jee Lim, Taekwon Kong In this paper, Fourier transform and physics knowledge were used to carry out the spectral analysis and to create a synthetic sound note of Cello. First, the wave forms and spectrums of Cello and other instruments were found to compare them each other. It was interesting to see that several instruments, such as brass instruments have much more energy in their second, third, and/or third harmonics than in the first frequency. Most of them generate a fuzzy tone. The brass and woodwind instruments show most of their energy in the second and third harmonics rather than the first frequency. Specifically, the string instrument shows strong first and third harmonic components. In the spectra, it is interesting to notice that the harmonics of the Cello are shown as equally spaced components. In the second section of the research, we have focused on accurately modeling the pluck of a Cello’s C4 note, to create synthetic wave using mathematical transformation. Because the entire plot is tool lengthy to model with the Fast Fourier Transform (FFT) function in Matlab, analysis on the first 20 periods of the plucked cello note was carried out. And we successfully created the synthetic wave using mathematical transformation. [Preview Abstract] |
|
F1.00036: Effect of Metal Proximity on a Pulsed Copper Coil H. K. Johnson, D. A. Schaffner, M. R. Brown, M. Kaur, C. Fiedler-Kawaguchi Generating and accelerating plasma in a stainless steel chamber affects the magnetic fields inside. These effects will decrease the field due to a pulsed coil (which will later be used to accelerate plasma) inside the chamber. This work is being done in conjunction with the Swarthmore Spheromak Experiment. Both facilities are collaborating in an attempt to accelerate and compress plasma as part of ARPA-E's Accelerating Low-Cost Plasma Heating and Assembly (ALPHA) program. Measurements of the impact of the chamber on the coil's magnetic fields were made using a B-dot probe inside the coil, which was placed at incremental distances from a metal plate. As the coil is moved from the plate, the plate's interference with the field was seen to exponentially decay. This process was repeated for stainless steel, aluminum, and copper, and a range of voltages (500-800V). At least seventy percent of the original signal was recovered within two inches. Pulsing the coil inside the stainless steel chamber resulted in signals about one third the strength of those measured outside of the chamber. The results of this experiment will be used to guide development of the stainless steel pulse-coil system for the Swarthmore ALPHA project. [Preview Abstract] |
|
F1.00037: Time of Flight Measurements of a Plasma Plume in a Glass Tube With and Without a Metal Liner C. Fiedler Kawaguchi, D. A. Schaffner, M. R. Brown, M. Kaur, H. K. Johnson Researchers have yet to attain a self-sustaining fusion reaction in which the amount of energy put in is less than that being produced. A novel approach for the compression and heating of plasma is under development at Swarthmore College with collaboration from Bryn Mawr College through the ARPA-E ALPHA program. Two acceleration modules are being designed to accelerate and compress plasma plumes using pulsed copper rings outside of a glass chamber (module one) and inside of a stainless steel chamber (module two). Measurements of plasma velocity are made using a time of flight technique using Hall probes and magnetic pickup probes (B-dot) probes to measure magnetic field at an array of spatial locations along the chamber. Results shows that the response time of the Hall probe chip used was too slow to register the fast changing fields. B-dot probes were shown to have a fast enough response. Time of flight measurements of field are made in the glass tube using cross correlation methods, with and without a stainless steel liner. Preliminary results show an average increase in the plasma plume velocity, from 38 km/s to 45 km/s, when the glass chamber is lined. [Preview Abstract] |
|
F1.00038: Flow past a Magnetic Obstacle in a Cylindrical Pipe Wayne N Manrakhan The effect of a magnetic obstacle, a uniform magnetic field, on an incompressible, conducting, viscous fluid has been fairly extensively studied. However most studies have modeled the fluid moving in a rectangular container. It would be interesting to see if similar physical effects such as the creation of vorticities in low Reynolds number flows occur in cylindrical containers. Thus a numerical study of the flow of a low Reynolds number, incompressible, conducting, viscous fluid in a cylindrical pipe with insulating walls around a single magnetic obstacle was performed. The magnetohydrodynamic (MHD) equations are solved using a highly conservative finite difference scheme on a non-uniform grid. The simulation show the creation of wakes, vorticities, and the shedding of vorticities though the dynamics of these vorticities are different from similar flows in rectangular ducts. These differences involving the motion and shedding of the vorticities will be highlighted. [Preview Abstract] |
|
F1.00039: Plasma Gun Design for Magnetohydrodynamic Turbulence Studies Carlos Cartagena, David Schaffner A long pulsed plasma gun is under development for magnetohydrodyanmic (MHD) turbulence studies at the Bryn Mawr College Plasma Laboratory. An avalanche breakdown of hydrogen gas occurs between two coaxial copper electrodes when biased at about 5kV creating a nearly fully ionized plasma. The plasma is injected into an externally generated magnetic field shaped to have radial field lines between the inner and outer electrodes. The field is maintained at the stuffing threshold--approximately where plasma injection due to currents balances plasma stagnation due to the field. This allows a steady plasma and magnetic helicity injection without depleting charge carriers in the gun region. Plasma is launched into a 24 cm diameter flux-conserving multi-diagnostic chamber, where magnetic field fluctuations and ion saturation current can be measured in order to examine their turbulent properties. [Preview Abstract] |
|
F1.00040: Atomic Force Microscope-induced Surface Modifications in CaMnO3 Thin Films Anthony Johnson, Samual Neubauer, Adeel Chaudhry, Cacie Hart, Bridget Lawson, David Houston, David Schaefer, Grace Yong, Rajeswari Kolagani Our recent work on epitaxial thin films of this material has shown that films with a tensile lattice mismatch strain exhibit structural and electrical properties that indicate oxygen deficiency. We observe thickness dependent changes in surface morphology that are consistent with strain-induced oxygen vacancies. Morphology of strained films shows a time dependence suggesting progressive oxygenation, as revealed by Atomic Force Microscopy (AFM). We have also studied surface modifications in these films introduced by a voltage biased AFM tip. We will discuss then characteristics of such surface modifications as compared to our previous results in thin films of hole-doped manganites. [Preview Abstract] |
|
F1.00041: Structure, Transport and Magnetoresistance Properties of Tensile Strained CaMnO3 Thin Films. Bridget Lawson, Dustin Ullery, Adeel Chaudhry, Samuel Neubauer, Cacie Hart, Rajeswari Kolagani We will present our studies of the structure, transport and magnetoresistance properties of tensile strained CaMnO3 thin films. We observe that the resistivity decreases significantly as the film thickness decreases. The decrease in resistivity is more pronounced in the films on (100) SrTiO3 with the larger lattice mismatch, the resistivity of the thinnest films being about 3 orders of magnitude lower than the of bulk CaMnO3. Structural changes accompanying resistivity changes cannot be fully explained as due to tensile strain, and suggest the presence of oxygen vacancies. These results suggest a coupling between tensile strain and oxygen deficiency, consistent with predictions from models based on density functional theory calculations. We observe a significant change in resistance under the application of magnetic field. [Preview Abstract] |
|
F1.00042: An Investigation of the Dynamic Characteristics of Magnetorheological Fluid Edward Wolfe, Navarun Jagatpal, Jyotsna Sau The investigation of magnetorheological fluid (MR fluid) provides insight into the capabilities and limitations of the next generation of automobiles, machines, and personal devices that will utilize adaptronics. These fluids are ideal for adaptronics because of their ability to change their viscosity in the presence of an applied magnetic field within milliseconds. The purpose of our current research is to show the effects of a static magnetic field on the flow rate of a sample MR fluid from LORD Corporation. Our experimental setup included a demonstration device manufactured by the LORD Corporation, consisting of two syringes coupled together with their MR fluid inside. We incorporated an Atwood machine to apply a constant 2-kilogram vertical load to the plunger of the syringe. The LORD fluid which consists of carbonyl iron suspended in water was subjected to various magnetic field strengths, and we measured the time for the fluid to flow from one syringe to the other. We found that the flow time of the MR fluid was an increasing function of the applied magnetic field strength. In the future we will synthesize our own MR fluid using iron oxide, various surfactants, and hydrocarbon or silicon based oil. We will investigate these MR fluid samples to determine their magnetic and rheological properties. [Preview Abstract] |
|
F1.00043: Temperature and Magnetic Field Effects on the Raman Spectra of TaSe$_{\mathrm{2}}$ J. Harding, A. R. Hight Walker, J. R. Simpson In bulk form, TaSe$_{\mathrm{2}}$ exhibits transitions between commensurate and incommensurate charge-density wave (CDW) phases, and is attracting interest for advance device applications. In order to explore the evolution of the groundstate CDW phase, mechanical exfoliation of bulk crystals provides freshly cleaved surfaces and may be used to prepare few- to single-layer flakes. In the present work, we extended our opto-thermal Raman measurements [1] on MoS$_{\mathrm{2}}$ to include other TMDs, specifically TaSe$_{\mathrm{2}}$, in both \textit{1T} and \textit{2H} crystallographic phases. A novel, magneto-Raman microscope system affords measurement of low-frequency (down to 10cm$^{\mathrm{-1}})$ vibrational modes as a function of both temperature (\textasciitilde 10K to 300K) and magnetic field (0T to 9T). The dependence of the observed Raman-active phonons on temperature and magnetic field will be discussed and compared with earlier results on MoS$_{\mathrm{2}}$. Specifically, we observe the appearance of low-frequency, zone-folded modes in the CDW state, which soften with temperature similar to the higher frequency, in-plane $E_{2g}$ mode. Additionally, magnetic-field dependence, including Faraday rotation in the micro-crystal insert will be discussed. [Preview Abstract] |
|
F1.00044: Thermodynamic Analysis of Transition Metal Oxide Clusters in the Hexane Isomerization Using Quantum Chemical Physics Haeun Lim, Eric Bae, Rachel Hur In this research, the catalyzing ability of transitional metal oxide compounds using a computational chemistry method was assessed in an effort to compute the measures of catalytic ability. Transitional metals, such as Ti, Zn and Pt, have been widely used as prominent catalysts for industrial applications. Catalytic oxidation reactions are crucial for chemical synthesis in pharmaceutical and petrochemical industries. Hexane isomers, such as 2,3 Dimethylbutane and 3-Methylpentane, are formed through the isomerization of hexane, which can be a source of energy by itself. It is a cleaner way to produce with higher efficiency because more branched isomers will release less harmful byproducts. In this research, the catalytic efficiencies of various Ta compounds in the hexane reaction were modeled and explained based on the compound’s electron structure. An overview of Tantalum oxide application and the advantages of certain Tantalum oxide among the same groups of metal oxides in the hexane reaction were presented. The Density Functional Theory was used to figure out the best catalyst for the conversion of isomers from hexane, which will advocate the pharmaceutical and petrochemical industries and economy. [Preview Abstract] |
|
F1.00045: Bio-image and Histogram Analysis of Human Bone Using Numerical and Computational Simulations Joo Sung Yi, Seong Hyeon Lee, Jiwoo Yoo Magnetic resonance imaging is a commonly used technique to produce an image of the anatomy of the subject through the use of radio waves, magnetism and computers. The data for the image is first transmitted as a k-space diagram, which is changed into an image through the Fourier Transformation. The images produced by MRI are accurate, and clear. However, there exist some drawbacks to the technology in that MRI produces clear, and rich representations of the area imaged, therefore takes a long production time. Time consumption is mainly caused by MRI’s use of every data in spatial frequency. In this paper, the histograms of the human bones were analyzed to distribute and enhance the image contrast toward more even colors. With the histograms obtained through the MatLab, the severity of the condition can be assessed, and specific levels of severities may have specific patterns to their respective histograms. The purpose of the present research is to develop a better algorithm, a more compatible Fourier Transformation equation in order to increase the resolution of the bio-image. [Preview Abstract] |
|
F1.00046: Fabrication of MeV electron spectrometer in light-matter interactions Siyu Luo, Sam Hughes, Patrick Grugen, Sharaa Alqarni, Barry Walker We describe the fabrication of an electron spectrometer for ultrahigh intensity laser interactions with individual atoms and molecules. The spectrometer consists of a main ultra-high vacuum(UHV) chamber, a turn table and a magnetic deflection spectrometer with electromagnets in UHV. The main chamber is pumped using turbomolecular pumps. The 0.6m diameter turn table is a two-layer design with the bottom layer fix onto the main chamber and the top layer coupling with the bottom layer with two grooves and stainless steel ball bearings. Each electromagnet is composed by a 0.1m diameter aluminum solenoid and 12 layers of 28-gauge polyimide coated copper wire. The electromagnets are house within custom UHV chambers cooled by deionized water. Electrons are detected by using a matched-set microchannel plate(MCP) detector set up in a high gain Chevron configuration. We present the electron calibration using Carbon-14 radioactive sources. [Preview Abstract] |
|
F1.00047: Harmonic spectral modulation of an optical frequency comb to control the formation of ultracold molecules Gengyuan Liu, Svetlana Malinovskaya A method for creation of ultracold molecules by stepwise adiabatic passage from the Feshbach state to the fundamentally ground state using an optical frequency comb is presented within a semiclassical multilevel model. The sine modulation of the spectral phase of the comb leads to the creation of a quasi-dark dressed state. An insignificant population of the excited state manifold in this dark state provides an efficient way of mitigating decoherence in the system. In contrast, the cosine modulation does not lead to the quasi-dark state formation. The results demonstrate the importance of the parity of the spectral chirp in quantum control. [Preview Abstract] |
|
F1.00048: Relativistic many body calculations of energies, matrix elements and lifetimes of Mo and Tc Ions. Dadong Huang, U.I. Safronova, M.S. Safronova, Z. Zuhrianda We carried a systematic study for $Mo^{6+}, Mo^{5+}, Mo^{4+}, Tc^{7+}, Tc^{6+}$ and $Tc^{5+}$. Valence removal energies, E1, E2 and M1 reduced matrix elements and lifetimes are determined. The calculations are carried out by using CI+MBPT and CI+all-order methods. In these methods the contributions from the core-core, core-valence and valence-valence correlations are accounted. The results are given along with energy comparison from the available experimental values. The determination of the spectra of Tc ions is needed for the stellar astrophysics studies. [Preview Abstract] |
|
F1.00049: Hyperfine quenching rates of $nsnp\,^3P_0-ns^2\,^1S_0$ transition in $^{25}$Mg, $^{87}$Sr and $^{113}$Cd Zuhrianda Zuhrianda, M.S. Safronova Determining the $nsnp\,^3P_0$ state decay rate is important for the development of atmic clock based on $nsnp\,^3P_0-ns^2\,^1S_0$ transition. In the fermionic isotope there exist a decay channel for the $nsnp\,^3P_0-ns^2\,^1S_0$ transition through the nuclear hyperfine interaction which can contributes to the total $nsnp\,^3P_0$ lifetime. We computed the hyperfine quenching rates of the $nsnp\,^3P_0-ns^2\,^1S_0$ transition in $^{25}$Mg, $^{87}$Sr and $^{113}$Cd. The calculations are carried out using the ab-initio CI-all order package. Our final results of the hyperfine quenching rates are 0.43 mHz for $^{25}$Mg, 9.7 mHz for $^{87}$Sr and 77 mHz for $^{113}$Cd. [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