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Physical Sciences and Mathematics Commons™

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2014

Faculty Publications

Engineering

Articles 1 - 11 of 11

Full-Text Articles in Physical Sciences and Mathematics

Sulfur Vacancies In Photorefractive Sn2P2S6 Crystals, Eric M. Golden, Sergey A. Basun, A. A. Grabar, I. M. Stoika, Nancy C. Giles, D. R. Evans, Larry E. Halliburton Dec 2014

Sulfur Vacancies In Photorefractive Sn2P2S6 Crystals, Eric M. Golden, Sergey A. Basun, A. A. Grabar, I. M. Stoika, Nancy C. Giles, D. R. Evans, Larry E. Halliburton

Faculty Publications

A photoinduced electron paramagnetic resonance (EPR) spectrum in single crystals of Sn2P2S6 (SPS) is assigned to an electron trapped at a sulfur vacancy. These vacancies are unintentionally present in undoped SPS crystals and are expected to play an important role in the photorefractive behavior of the material. Nonparamagnetic sulfur vacancies are formed during the initial growth of the crystal. Subsequent illumination below 100 K with 442 nm laser light easily converts these vacancies to EPR-active defects. The resulting S = 1/2 spectrum shows well-resolved and nearly isotropic hyperfine interactions with two P ions and two Sn ions. Partially resolved interactions …

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Synthesis And Formation Mechanism Of Cuins2 Nanocrystals With A Tunable Phase, Chao Yu, Linlin Zhang, Long Tian, Dan Liu, Fanglin Chen, Cheng Wang Nov 2014

Synthesis And Formation Mechanism Of Cuins2 Nanocrystals With A Tunable Phase, Chao Yu, Linlin Zhang, Long Tian, Dan Liu, Fanglin Chen, Cheng Wang

Faculty Publications

Chalcopyrite CuInS2 (CIS) hierarchical structures composed of nanoflakes with a thickness of about 5 nm were synthesized by a facial solvothermal method. The thermodynamically metastable wurtzite phase CIS would be obtained by using InCl3 instead of In(NO3)3 as In precursor. The effects of the In precursor and the volume of concentrated HCl aqueous solution on the phases and morphologies of CIS nanocrystals have been systematically investigated. Experimental results indicated that the obtained phases of CIS nanocrystals were predominantly determined by precursor-induced intermediate products. The photocatalytic properties of chalcopyrite and wurtzite CIS in visible-light-driven degradation of …

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Machine Learning Nuclear Detonation Features, Daniel T. Schmitt, Gilbert L. Peterson Oct 2014

Machine Learning Nuclear Detonation Features, Daniel T. Schmitt, Gilbert L. Peterson

Faculty Publications

Nuclear explosion yield estimation equations based on a 3D model of the explosion volume will have a lower uncertainty than radius based estimation. To accurately collect data for a volume model of atmospheric explosions requires building a 3D representation from 2D images. The majority of 3D reconstruction algorithms use the SIFT (scale-invariant feature transform) feature detection algorithm which works best on feature-rich objects with continuous angular collections. These assumptions are different from the archive of nuclear explosions that have only 3 points of view. This paper reduces 300 dimensions derived from an image based on Fourier analysis and five edge …

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Timing Mark Detection On Nuclear Detonation Video, Daniel T. Schmitt, Gilbert L. Peterson Oct 2014

Timing Mark Detection On Nuclear Detonation Video, Daniel T. Schmitt, Gilbert L. Peterson

Faculty Publications

During the 1950s and 1960s the United States conducted and filmed over 200 atmospheric nuclear tests establishing the foundations of atmospheric nuclear detonation behavior. Each explosion was documented with about 20 videos from three or four points of view. Synthesizing the videos into a 3D video will improve yield estimates and reduce error factors. The videos were captured at a nominal 2500 frames per second, but range from 2300-3100 frames per second during operation. In order to combine them into one 3D video, individual video frames need to be correlated in time with each other. When the videos were captured …

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Querie: Collaborative Database Exploration, Magdalini Eirinaki, Suju Abraham, Neoklis Polyzotis, Naushin Shaikh Jul 2014

Querie: Collaborative Database Exploration, Magdalini Eirinaki, Suju Abraham, Neoklis Polyzotis, Naushin Shaikh

Faculty Publications

No abstract provided.

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Effect Of Z1/2, Eh5, And Ci1 Deep Defects On The Performance Of N-Type 4h-Sic Epitaxial Layers Schottky Detectors: Alpha Spectroscopy And Deep Level Transient Spectroscopy Studies, M. A. Mannan, S. K. Chaudhuri, K. V. Nguyen, K. C. Mandal Jun 2014

Effect Of Z1/2, Eh5, And Ci1 Deep Defects On The Performance Of N-Type 4h-Sic Epitaxial Layers Schottky Detectors: Alpha Spectroscopy And Deep Level Transient Spectroscopy Studies, M. A. Mannan, S. K. Chaudhuri, K. V. Nguyen, K. C. Mandal

Faculty Publications

No abstract provided.

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Copper Doping Of Zno Crystals By Transmutation Of 64Zn To 65Cu: An Electron Paramagnetic Resonance And Gamma Spectroscopy Study, Matthew C. Recker, John W. Mcclory, Maurio S. Holston, Eric M. Golden, Nancy C. Giles, Larry E. Halliburton Jun 2014

Copper Doping Of Zno Crystals By Transmutation Of 64Zn To 65Cu: An Electron Paramagnetic Resonance And Gamma Spectroscopy Study, Matthew C. Recker, John W. Mcclory, Maurio S. Holston, Eric M. Golden, Nancy C. Giles, Larry E. Halliburton

Faculty Publications

Transmutation of 64Zn to 65Cu has been observed in a ZnO crystal irradiated with neutrons. The crystal was characterized with electron paramagnetic resonance (EPR) before and after the irradiation and with gamma spectroscopy after the irradiation. Major features in the gamma spectrum of the neutron-irradiated crystal included the primary 1115.5 keV gamma ray from the 65Zn decay and the positron annihilation peak at 511 keV. Their presence confirmed the successful transmutation of 64Zn nuclei to 65Cu. Additional direct evidence for transmutation was obtained from the EPR of Cu2+ ions (where 63Cu and 65 …

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Modeling The Thermosphere As A Driven-Dissipative Thermodynamic System, William R. Frey, C. S. Lin, Matthew B. Garvin, Ariel O. Acebal Apr 2014

Modeling The Thermosphere As A Driven-Dissipative Thermodynamic System, William R. Frey, C. S. Lin, Matthew B. Garvin, Ariel O. Acebal

Faculty Publications

Thermospheric density impacts satellite position and lifetime through atmospheric drag. More accurate specification of thermospheric temperature, a key input to current models such as the High Accuracy Satellite Drag Model, can decrease model density errors. This paper improves the model of Burke et al. (2009) to model thermospheric temperatures using the magnetospheric convective electric field as a driver. In better alignment with Air Force satellite tracking operations, we model the arithmetic mean temperature, T 1/2, defined by the Jacchia (1977) model as the mean of the daytime maximum and nighttime minimum exospheric temperatures occurring in opposite hemispheres at a …

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Triplet Ground State Of The Neutral Oxygen-Vacancy Donor In Rutile Tio2, A. T. Brant, Eric M. Golden, Nancy C. Giles, Shan Yang, M. A. R. Sarker, S. Watauchi, M. Nagao, I. Tanaka, D. A. Tryk, A. Manivannan, Larry E. Halliburton Mar 2014

Triplet Ground State Of The Neutral Oxygen-Vacancy Donor In Rutile Tio2, A. T. Brant, Eric M. Golden, Nancy C. Giles, Shan Yang, M. A. R. Sarker, S. Watauchi, M. Nagao, I. Tanaka, D. A. Tryk, A. Manivannan, Larry E. Halliburton

Faculty Publications

Electron paramagnetic resonance (EPR) is used to investigate the triplet (S = 1) ground state of the neutral oxygen vacancy in bulk rutile TiO2 crystals. This shallow donor consists of an oxygen vacancy with two nearest-neighbor, exchange-coupled 3+ ions located along the [001] direction and equidistant from the vacancy. The spins of the two trapped electrons, one at each 3+ ion, align parallel to give the S = 1 state. These neutral oxygen vacancies are formed near 25 K in as-grown oxidized TiO2 crystals by illuminating with sub-band-gap 442 nm laser light. The angular dependence of the EPR …

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Neutral Nitrogen Acceptors In Zno: The 67Zn Hyperfine Interactions, Eric M. Golden, S. M. Evans, Larry E. Halliburton, Nancy C. Giles Mar 2014

Neutral Nitrogen Acceptors In Zno: The 67Zn Hyperfine Interactions, Eric M. Golden, S. M. Evans, Larry E. Halliburton, Nancy C. Giles

Faculty Publications

Electron paramagnetic resonance (EPR) is used to characterize the 67Zn hyperfine interactions associated with neutral nitrogen acceptors in zinc oxide. Data are obtained from an n-type bulk crystal grown by the seeded chemical vapor transport method. Singly ionized nitrogen acceptors (N−) initially present in the crystal are converted to their paramagnetic neutral charge state (N0) during exposure at low temperature to 442 or 633 nm laser light. The EPR signals from these N0 acceptors are best observed near 5 K. Nitrogen substitutes for oxygen ions and has four nearest-neighbor cations. The zinc ion …

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Tuning The Underwater Oleophobicity Of Graphene Oxide Coatings Via Uv Irradiation, H. Li, Yi Huang, Y. Mao, W. Xu, Harry J. Ploehn, Miao Yu Jan 2014

Tuning The Underwater Oleophobicity Of Graphene Oxide Coatings Via Uv Irradiation, H. Li, Yi Huang, Y. Mao, W. Xu, Harry J. Ploehn, Miao Yu

Faculty Publications

Ultraviolet (UV) irradiation was utilized to gradually modify the chemistry and structure of graphene oxide (GO) flakes, as confirmed by XPS and AFM. Ultrathin GO coatings/membranes, made of UV-irradiated flakes, showed tunable underwater oleophobicity. UV-treated, superoleophobic GO membranes exhibited excellent antifouling capability for oil/water separation.

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