Rapid Analysis Of Plutonium Surrogate Material Via Hand-Held Laser-Induced Breakdown Spectroscopy,
2020
Air Force Institute of Technology
Rapid Analysis Of Plutonium Surrogate Material Via Hand-Held Laser-Induced Breakdown Spectroscopy, Ashwin P. Rao
Theses and Dissertations
This work investigated the capability of a portable LIBS device to detect and quantify dopants in plutonium surrogate alloys, specifically gallium, which is a common stabilizer used in plutonium alloys. The SciAps Z500-ER was utilized to collect spectral data from cerium-gallium alloys of varying gallium concentrations. Calibration models were built to process spectra from the Ce-Ga alloys and calculate gallium concentration from spectral emission intensities. Univariate and multivariate analysis techniques were used to determine limits of detection of different emission line ratios. Spatial mapping measurements were conducted to determine the device's ability to detect variations in gallium concentration on the …
Comparison Of The Accuracy Of Rayleigh-Rice Polarization Factors To Improve Microfacet Brdf Models,
2020
Air Force Institute of Technology
Comparison Of The Accuracy Of Rayleigh-Rice Polarization Factors To Improve Microfacet Brdf Models, Rachel L. Wolfgang
Theses and Dissertations
Microfacet BRDF models assume that a surface has many small microfacets making up the roughness of the surface. Despite their computational simplicity in applications in remote sensing and scene generation, microfacet models lack the physical accuracy of wave optics models. In a previous work, Butler proposed to replace the Fresnel reflectance term of microfacet models with the Rayleigh-Rice polarization factor, Q, to create a more accurate model. This work examines the novel model that combines microfacet and wave optics terms for its accuracy in the pp and ss polarized cases individually. The model is fitted to the polarized data in …
Liquid-Phase Mega-Electron-Volt Ultrafast Electron Diffraction,
2020
University of Nebraska–Lincoln
Liquid-Phase Mega-Electron-Volt Ultrafast Electron Diffraction, J. P.F. Nunes, K. Ledbetter, M. Lin, M. Kozina, D. P. Deponte, E. Biasin, Martin Centurion, C. J. Crissman, M. Dunning, S. Guillet, K. Jobe, Y. Liu, M. Mo, X. Shen, R. Sublett, S. Weathersby, C. Yoneda, T. J. A. Wolf, Jie Yang, A. A. Cordones, Xijie Wang
Martin Centurion Publications
The conversion of light into usable chemical and mechanical energy is pivotal to several biological and chemical processes, many of which occur in solution. To understand the structure-function relationships mediating these processes, a technique with high spatial and temporal resolutions is required. Here, we report on the design and commissioning of a liquid-phase mega-electron-volt (MeV) ultrafast electron diffraction instrument for the study of structural dynamics in solution. Limitations posed by the shallow penetration depth of electrons and the resulting information loss due to multiple scattering and the technical challenge of delivering liquids to vacuum were overcome through the use of …
Near-Infrared-Sensitive Photorefractive Sn2P2S6 Crystals Grown By The Bridgman Method,
2020
National Academy of Sciences, Ukraine
Near-Infrared-Sensitive Photorefractive Sn2P2S6 Crystals Grown By The Bridgman Method, O. M. Shumelyuk, A. Y. Volkov, Y. Skrypka, Larry E. Halliburton, Nancy C. Giles, Christopher A. Lenyk, Sergey A. Basun, A. A. Grabar, Y. M. Vysochansky, S. G. Odoulov, D. R. Evans
Faculty Publications
Ferroelectric tin hypothiodiphosphate (Sn2P2S6) crystals are well-known for their significant piezoelectric, electro-optic, and nonlinear optical properties. These crystals have usually been grown by a vapor transport technique. We report in this paper on the first study of photorefractive nonlinearity in Sn2P2S6 crystals grown by the Bridgman method. Pronounced photorefraction is observed in the near-infrared region of the spectrum even with no preliminary optical sensitizing.
Effects Of Intrinsic Defects And Alloying With Fe On The Half-Metallicity Of Co2Mnsi,
2020
University of Nebraska - Lincoln
Effects Of Intrinsic Defects And Alloying With Fe On The Half-Metallicity Of Co2Mnsi, G. G. Baez Flores, Ivan A. Zhuravlev, Kirill Belashchenko
Kirill Belashchenko Publications
The electronic structure and half-metallic gap of Co2MnSi in the presence of crystallographic defects, partial Fe substitution for Mn, and thermal spin fluctuations are studied using the coherent potential approximation and the disordered local moment method. In the presence of 5% Co or Mn vacancies the Fermi level shifts down to the minority-spin valence-band maximum. In contrast to NiMnSb, both types of Mn antisite defects in Co2MnSi are strongly exchange coupled to the host magnetization, and thermal spin fluctuations do not strongly affect the half-metallic gap. Partial substitution of Mn by Fe results in considerable changes in the Bloch spectral …
Quantum Control With Spinor Bose-Einstein Condensates,
2020
San Jose State University
Quantum Control With Spinor Bose-Einstein Condensates, Hilary M. Hurst
Faculty Research, Scholarly, and Creative Activity
Understanding and controlling many-body quantum systems in noisy environments is paramount to developing robust quantum technologies. An external environment can be thought of as a measurement reservoir which extracts information about the quantum system. Cold atoms are well suited to examine system-environment interaction via weak (i.e. minimally destructive) measurement techniques, wherein the measurement probe acts as the environment and also provides a noisy record of system dynamics. The measurement record can then be used in a feedback scheme, opening the door to real time control of quantum gases. In this talk I discuss our theoretical proposal to use weak measurement …
A Computationally-Efficient Bound For The Variance Of Measuring The Orientation Of Single Molecules,
2020
Washington University in St. Louis
A Computationally-Efficient Bound For The Variance Of Measuring The Orientation Of Single Molecules, Tingting Wu, Tianben Ding, Hesam Mazidi, Oumeng Zhang, Matthew D. Lew
Electrical & Systems Engineering Publications and Presentations
Modulating the polarization of excitation light, resolving the polarization of emitted fluorescence, and point spread function (PSF) engineering have been widely leveraged for measuring the orientation of single molecules. Typically, the performance of these techniques is optimized and quantified using the Cramér-Rao bound (CRB), which describes the best possible measurement variance of an unbiased estimator. However, CRB is a local measure and requires exhaustive sampling across the measurement space to fully characterize measurement precision. We develop a global variance upper bound (VUB) for fast quantification and comparison of orientation measurement techniques. Our VUB tightly bounds the diagonal elements of the …
Overview Of Trends In Indian Optics Research (2008 – 2018),
2020
Kuvempu University
Overview Of Trends In Indian Optics Research (2008 – 2018), Mallikarjun Kappi, Biradar B S
Library Philosophy and Practice (e-journal)
The present study deals with the assessment of Indian optics research output as reflected in Web of Science (WOS) database for the period 2008 to 2018 for identifying the research output in the field of optics literature. It also provides a comparative evaluation and performance of different types of scientometric indicators, such as number of publications, number of citations and collaboration from India. The Indian optics research has increased exponentially over the last decade.
Validation Of Trap Density Theory In Single Layer Organic Light Emitting Diodes With Tris(8 Hydroxyquinolinato)Aluminium As The Emissive Material,
2020
Universiti Malaya
Validation Of Trap Density Theory In Single Layer Organic Light Emitting Diodes With Tris(8 Hydroxyquinolinato)Aluminium As The Emissive Material, Zaini Mohd Suffian
Student Works (2020-2029)
Organic light-emitting diodes (OLEDs) rapidly evolving as the future of solid-state lighting and display application due to its numerous advantages and features. However, the efficiency, lifetime, and fabrication method still need to be improved. Even in solving efficiency issues in the device, there are many challenges to be addressed and overcome. In theory, charge transport phenomena contribute greatly towards increasing or improving the device efficiency. The magnitude of carrier mobility determines the performance of the device, as it influenced device efficiency. For organic semiconductor such as OLED, space-charge limited current (SCLC) theory was used to determine the mobility of the …
Radiation-Induced Electron And Hole Traps In Ge1-XSnX (X = 0-0.094),
2020
Air Force Institute of Technology
Radiation-Induced Electron And Hole Traps In Ge1-XSnX (X = 0-0.094), Michael R. Hogsed, Kevin K. Choe, Norman Miguel, Buguo Wang, John Kouvetakis
Faculty Publications
The band structure of germanium changes significantly when alloyed with a few percent concentrations of tin, and while much work has been done to characterize and exploit these changes, the corresponding deep-level defect characteristics are largely unknown. In this paper, we investigate the dominant deep-level defects created by 2 MeV proton irradiation in Ge1 -xSnx (x = 0.0, 0.020, 0.053, 0.069, and 0.094) diodes and determine how the ionization energies of these defects change with tin concentrations. Deep-level transient spectroscopy measurements approximate the ionization energies associated with electron transitions to/from the valence band (hole traps) and conduction band (electron traps) …
Guidelines For Studying The Dynamics Of Nanostructural Phenomena In Liquids By Dynamic Light Scattering.,
2020
Samarkand state university
Guidelines For Studying The Dynamics Of Nanostructural Phenomena In Liquids By Dynamic Light Scattering., Shavkat Esirgapovich Qarshiboyev, Lionard Sabirov, Leonid Chaikov, Marina Kirichenko
Scientific Journal of Samarkand University
The paper describes the principles of correlation spectroscopy of scattered light and a method for determining the size of particles suspended in a liquid using such spectroscopy - the method of dynamic light scattering (DLS). Some features of the application of the DLS method are considered.
Itinerant Ferromagnetism And Intrinsic Anomalous Hall Effect In Amorphous Iron-Germanium,
2020
University of California, Berkeley
Itinerant Ferromagnetism And Intrinsic Anomalous Hall Effect In Amorphous Iron-Germanium, D. S. Bouma, Z. Chen, B. Zhang, F. Bruni, M. E. Flatté, A. Ceballos, R. Streubel, L. W. Wang, R. Q. Wu, F. Hellman
Robert Streubel Papers
The amorphous iron-germanium system (a-FexGe1-x) lacks long-range structural order and hence lacks a meaningful Brillouin zone. The magnetization of a-FexGe1-x is well explained by the Stoner model for Fe concentrations x above the onset of magnetic order around x=0.4, indicating that the local order of the amorphous structure preserves the spin-split density of states of the Fe-3d states sufficiently to polarize the electronic structure despite k being a bad quantum number. Measurements reveal an enhanced anomalous Hall resistivity ρxyAH relative to crystalline FeGe; this ρxyAH is compared to density-functional …
Structuring Light For Investigating Optical Vortices,
2020
University of Denver
Structuring Light For Investigating Optical Vortices, Andrew Voitiv, Mark Siemens
DU Undergraduate Research Journal Archive
Vortices are well known in our world: tornadoes, hurricanes, and quickly stirred iced tea all demonstrate the vortex phenomenon. In addition to these classical fluids, vortices exist in laser light. While classical fluid vortex dynamics is one of the oldest studied physics problems, the study of optical vortices is only a few decades old. Paralleling the community’s curiosity of quantized vortices in quantum fluids, such as super fluid helium and Bose-Einstein condensate, there is immense interest in the study of optical vortices. In this article, we cover the basic theory of structuring light to generate optical vortices and then discuss …
Dual-Axis Solar Tracker,
2020
Central Washington University
Dual-Axis Solar Tracker, Bryan Kennedy
All Undergraduate Projects
Renewable energies, and fuels that are not fossil fuel-based, are one of the prolific topics of debate in modern society. With climate change now becoming a primary focus for scientists and innovators of today, one of the areas for the largest amount of potential and growth is that of the capturing and utilization of Solar Energy. This method involves using a mechanical system to track the progression of the sun as it traverses the sky throughout the day. A dual-axis solar tracker such as the one designed and built for this project, can follow the sun both azimuthally and in …
Diffusion Doping Of Cobalt In Rod-Shape Anatase Tio2 Nanocrystals Leads To Antiferromagnetism†,
2020
University of South Dakota
Diffusion Doping Of Cobalt In Rod-Shape Anatase Tio2 Nanocrystals Leads To Antiferromagnetism†, Shahzahan Mia, Shelton J.P. Varapragasam, Aravind Baride, Choumini Balasanthiran, Balamurugan Balasubramanian, Robert M. Rioux, James D. Hoefelmeyer
Nebraska Center for Materials and Nanoscience: Faculty Publications
Cobalt(II) ions were adsorbed to the surface of rod-shape anatase TiO2 nanocrystals and subsequently heated to promote ion diffusion into the nanocrystal. After removal of any remaining surface bound cobalt, a sample consisting of strictly cobalt-doped TiO2 was obtained and characterized with powder Xray diffraction, transmission electron microscopy, UV-visible spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectroscopy, SQUID magnetometry, and inductively-coupled plasma atomic emission spectroscopy. The nanocrystal morphology was unchanged in the process and no new crystal phases were detected. The concentration of cobalt in the doped samples linearly correlates with the initial loading of cobalt(II) ions on the nanocrystal surface. Thin …
Characterizing Complexity In A Semiconductor With Optical Feedback From Two Mirrors,
2020
Eastern Washington University
Characterizing Complexity In A Semiconductor With Optical Feedback From Two Mirrors, Layla M. Abrams
2020 Symposium Posters
Lasers are stable devices with a broad spectrum of applications. They can be perturbed to induce complex dynamics in their output intensity. One interesting regime in semiconductor lasers is that the output intensity of the laser emits a sequence of non-regular optical spikes. This behavior resembles that of neurons. We use a semiconductor laser with optical feedback from two mirrors to characterize the behavior of the laser's power output. The data is then analyzed by transforming the intensity time series into a sequence of patterns or words. By doing this we want to explore how the laser changes its preferred …
Detection Of Decoupled Surface And Bulk States In Epitaxial Orthorhombic Sriro3 Thin Films,
2020
University of Nebraska-Lincoln
Detection Of Decoupled Surface And Bulk States In Epitaxial Orthorhombic Sriro3 Thin Films, Prescott E. Evans, Takashi Komesu, Le Zhang, Ding-Fu Shao, Andrew J. Yost, Shiv Kumar, Eike F. Schwier, Kenya Shimada, Evgeny Y. Tsymbal, Xia Hong, P. A. Dowben
Peter Dowben Publications
We report the experimental evidence of evolving lattice distortion in high quality epitaxial orthorhombic SrIrO3(001) thin films fully strained on (001) SrTiO3 substrates. Angle-resolved X-ray photoemission spectroscopy studies show that the surface layer of 5 nm SrIrO3 films is Sr–O terminated, and subsequent layers recover the semimetallic state, with the band structure consistent with an orthorhombic SrIrO3(001) having the lattice constant of the substrate. While there is no band folding in the experimental band structure, additional super-periodicity is evident in low energy electron diffraction measurements, suggesting the emergence of a transition layer with crystal symmetry evolving from the SrTiO3 substrate …
Manipulation Of The Molecular Spin Crossover Transition Of Fe(H2b(Pz)2)2(Bipy) By Addition Of Polar Molecules,
2020
University of Nebraska - Lincoln
Manipulation Of The Molecular Spin Crossover Transition Of Fe(H2b(Pz)2)2(Bipy) By Addition Of Polar Molecules, Paulo S. Costa, Guanhua Hao, Alpha T. N'Diaye, Lucie Routaboul, Pierre Braunstein, Xin Zhang, Jian Zhang, Thilini K. Ekanayaka, Qin Yin Shi, V. L. Schlegel, Bernard Doudin, Axel Enders, Peter Dowben
Peter Dowben Publications
The addition of various dipolar molecules is shown to affect the temperature dependence of the spin state occupancy of the much studied spin crossover Fe(II) complex, [Fe{H2B(pz)2}2(bipy)] (pz = pyrazol-1-yl, bipy = 2,2′-bipyridine). Specifically, the addition of benzimidazole results in a re-entrant spin crossover transition, i.e. the spin state starts in the mostly low spin state, then high spin state occupancy increases, and finally the high spin state occupancy decreases with increasing temperature. This behavior contrasts with that observed when the highly polar p -benzoquinonemonoimine zwitterion C6H2(..NH2)2(..O)2 was mixed with [Fe{H2B(pz)2}2(bipy)], which resulted in locking [Fe{H2B(pz)2}2(bipy)] largely into a low …
Launching A New Dimension With 3d Magnetic Nanostructures,
2020
Lawrence Berkeley National Laboratory
Launching A New Dimension With 3d Magnetic Nanostructures, Peter Fischer, Dédalo Sanz-Hernández, Robert Streubel, Amalio Fernández-Pacheco
Robert Streubel Papers
The scientific and technological exploration of three-dimensional magnetic nanostructures is an emerging research field that opens the path to exciting novel physical phenomena, originating from the increased complexity in spin textures, topology, and frustration in three dimensions. One can also anticipate a tremendous potential for novel applications with those systems in a magnetic sensor and information processing technologies in terms of improved energy efficiency, processing speed, functionalities, and miniaturization of future spintronic devices. These three-dimensional structures are distinct from traditional bulk systems as they harness the scientific achievements of nanomagnetism, which aimed at lowering the dimensions down to the atomic …
Spectroscopic Study On Pseudomonas Aeruginosa Biofilm In The Presence Of The Aptamer-Dna Scaffolded Silver Nanoclusters,
2020
Stephen F Austin State University
Spectroscopic Study On Pseudomonas Aeruginosa Biofilm In The Presence Of The Aptamer-Dna Scaffolded Silver Nanoclusters, Bidisha Sengupta, Prakash Adhikari, Esther Mallet, Ronald Havner, Prabhakar Pradhan
Faculty Publications
We report the effectiveness of silver nanocluster (Ag-NC) against the biofilm of Pseudomonas aeruginosa (PA). Two DNA aptamers specific for PA and part of their sequences were chosen as templates for growing the Ag-NC. While circular dichroism (CD) studies determined the presence of secondary structures, UV/Vis absorption, and fluorescence spectroscopic studies confirmed the formation of the fluorescent Ag-NC on the DNA templates. Furthermore, mesoscopic physics-based partial wave spectroscopy (PWS) was used to analyze the backscattered light signal that can detect the degree of nanoscale mass density/refractive index fluctuations to identify the biofilm formation, comparatively among the different aptamers with respect …
