Optical Characterization Of Silver Doped Poly (Vinyl Alcohol) Films,
2010
Al Mustasiriyah University
Optical Characterization Of Silver Doped Poly (Vinyl Alcohol) Films, W. A. Jabbar, N. F. Habubi, S. S. Chiad
Journal of the Arkansas Academy of Science
Silver-doped PVA films were prepared by casting method in order to study the effect of silver on the optical properties of poly(vinyl alcohol) using UV/VIS spectroscopy. It was found that these thin films have an indirect optical band gap (2.4-1.3) eV as the doping percentage increase. Extinction coefficient and refractive index increase as the doping percentage increase, while in general the optical dispersion parameters show an opposite behavior with doping.
Sulfur K-Edge Photo-Fragmentation Of Ethylene Sulfide,
2010
University of Nevada, Las Vegas
Sulfur K-Edge Photo-Fragmentation Of Ethylene Sulfide, Wayne C. Stolte, Gunnar Ohrwall
Chemistry and Biochemistry Faculty Research
We have investigated the photofragmentation properties of the three-membered ring heterocyclic molecule ethylene sulfide or thiirane, C2H4S, by time-of-flight mass spectroscopy. Positive ions have been collected as a function of photon energy around the S K ionization threshold. Branching ratios were derived for all detected ions, which are informative of the decay dynamics and photofragmentation patterns of the core-excited species. We present a new assignment of the spectral features around the S K-edge.
The Study Of Radio Frequency Interference (Rfi) For Radio Astronomy In Some Remote Locations In Peninsular Malaysia.,
2010
Universiti Malaya
The Study Of Radio Frequency Interference (Rfi) For Radio Astronomy In Some Remote Locations In Peninsular Malaysia., Syed Bahari Ramadzan Syed Adnan
Student Works (2010-2019)
Radio Frequency Interference (RFI) is the main parameter to find the best site for radio astronomy research development. The increasing levels of RFI will pose a big problem for researchers in the radio astronomy field. The radio astronomers are encouraged to choose sites as free as possible from interference. In this research we aimed to survey the RFI at frequency 1 MHz-2000MHz to look the overview of the RFI profile and at frequency 1419 MHz-1421 MHz to monitor the RFI profile at Hydrogen line frequency (1420.4 MHz). We chose Peninsular Malaysia as the research area for RFI observation. We have …
Characterization Of An Inductively Coupled Plasma Produced In Argon At 13.56 Mhz.,
2010
Universiti Malaya
Characterization Of An Inductively Coupled Plasma Produced In Argon At 13.56 Mhz., Lim Ai Nuan
Student Works (2010-2019)
The electrical and plasma characteristics of radio frequency (13.56 MHz) inductively coupled argon plasma (RF ICP) were studied in this project. On the electrical breakdown properties, the breakdown voltage has a general appearance of Paschen’s curve and the minimum is achieved at 0.1 mbar. After ignition, two modes of discharge exist, namely, the E mode at low RF power and H mode at high RF power. Mode transition that occurs is accompanied by abrupt changes in both electrical and plasma characteristics. Hysteresis is observed in the mode transitions and has a minimum at 0.1 mbar. The resistance reflected into the …
Deposition Of High-Quality Hfo2 On Graphene And The Effect Of Remote Oxide Phonon Scattering,
2010
Pennsylvania State University
Deposition Of High-Quality Hfo2 On Graphene And The Effect Of Remote Oxide Phonon Scattering, K. Zou, X. Hong, D. Keefer, J. Zhu
Xia Hong Publications
We demonstrate atomic layer deposition of high-quality dielectric HfO2 films on graphene and determine the magnitude of remote oxide surface phonon scattering in dual-oxide structures. The carrier mobility in these HfO2-covered graphene samples reaches 20 000 cm2/Vs at low temperature. Distinct contributions to the resistivity from surface optical phonons in the SiO2 substrate and the HfO2 overlayer are isolated. At 300 K, surface phonon modes of the HfO2 film centered at 54 meV limit the mobility to approximately 20 000 cm2/Vs.
Unusual Resistance Hysteresis In N-Layer Graphene Field Effect Transistors Fabricated On Ferroelectric Pb(Zr0.2Ti0.8)O3,
2010
University of Nebraska–Lincoln
Unusual Resistance Hysteresis In N-Layer Graphene Field Effect Transistors Fabricated On Ferroelectric Pb(Zr0.2Ti0.8)O3, X. Hong, J. Hoffman, A. Posadas, K. Zou, C. H. Ahn, J. Zhu
Xia Hong Publications
We have fabricated n-layer graphene field effect transistors on epitaxial ferroelectric Pb(Zr0.2Ti0.8)O3 (PZT) thin films. At low gate voltages, PZT behaves as a high-k dielectric with k up to 100. An unusual resistance hysteresis occurs in gate sweeps at high voltages, with its direction opposite to that expected from the polarization switching of PZT. The relaxation of the metastable state is thermally activated, with an activation barrier of 50–110 meV and a time constant of 6 h at 300 K. We attribute its origin to the slow dissociation/recombination dynamics of water molecules adsorbed at …
Lattice Dynamical Probe Of Charge Order And Antipolar Bilayer Stacking In Lufe2o4,
2010
University of Nebraska-Lincoln
Lattice Dynamical Probe Of Charge Order And Antipolar Bilayer Stacking In Lufe2o4, X. S. Xu, J. De Groot, Q.-C. Sun, B. C. Sales, D. Mandrus, M. Angst, A. P. Litvinchuk, J. L. Musfeldt
Xiaoshan Xu Papers
We investigated the infrared response of LuFe2O4 through the series of charge, magnetic, and structural transitions. All vibrational modes couple strongly to the charge order, whereas the LuO zone-folding modes are also sensitive to magnetic order and structural distortion. The dramatic splitting of the LuO2 layer mode is attributed to charge-rich/poor proximity effects and its temperature dependence reveals the antipolar nature of the W layer pattern.
Tunable Band Gap In Bi(Fe1−Xmnx)O3 Films,
2010
University of Nebraska-Lincoln
Tunable Band Gap In Bi(Fe1−Xmnx)O3 Films, X. S. Xu, J. F. Ihlefeld, J. H. Lee, O. K. Ezekoye, E. Vlahos, R. Ramesh, V. Gopalan, X. Q. Pan, D. G. Schlom, J. L. Musfeldt
Xiaoshan Xu Papers
In order to investigate band gap tunability in polar oxides, we measured the optical properties of a series of Bi(Fe1−xMnx)O3 thin films. The absorption response of the mixed metal solid solutions is approximately a linear combination of the characteristics of the two end members, a result that demonstrates straightforward band gap tunability in this system.
Magnetodielectric Coupling Of Infrared Phonons In Single-Crystal Cu2oseo3,
2010
University of Florida
Magnetodielectric Coupling Of Infrared Phonons In Single-Crystal Cu2oseo3, K. H. Miller, X. S. Xu, H. Berger, E. S. Knowles, D. J. Arenas, M. W. Meisel, D. B. Tanner
Xiaoshan Xu Papers
Reflection and transmission as a function of temperature (5–300 K) have been measured on a single crystal of the magnetoelectric ferrimagnetic compound Cu2OSeO3 utilizing light spanning the far infrared to the visible portions of the electromagnetic spectrum. The complex dielectric function and optical properties were obtained via Kramers-Kronig analysis and by fits to a Drude-Lortentz model. The fits of the infrared phonons show a magnetodielectric effect near the transition temperature (Tc~60 K). Assignments to strong far-infrared phonon modes have been made, especially those exhibiting anomalous behavior around the transition temperature.
Adsorption-Controlled Growth Of Bimno3 Films By Molecular-Beam Epitaxy,
2010
Cornell University
Adsorption-Controlled Growth Of Bimno3 Films By Molecular-Beam Epitaxy, J. H. Lee, X. Ke, R. Misra, J. F. Ihlefeld, X. S. Xu, Z. G. Mei, T. Heeg, M. Roeckerath, J. Schubert, Z. K. Liu, J. L. Musfeldt, P. Schiffer, D. G. Schlom
Xiaoshan Xu Papers
We have developed the means to grow BiMnO3 thin films with unparalleled structural perfection by reactive molecular-beam epitaxy and determined its band gap. Film growth occurs in an adsorption-controlled growth regime. Within this growth window bounded by oxygen pressure and substrate temperature at a fixed bismuth overpressure, single-phase films of the metastable perovskite BiMnO3 may be grown by epitaxial stabilization. X-ray diffraction reveals phase-pure and epitaxial films with w rocking curve full width at half maximum values as narrow as 11 arc sec (0.003°). Optical absorption measurements reveal that BiMnO3 has a direct band gap of 1.1±0.1 …
Dynamical Theory Calculations Of Spin-Echo Resolved Grazing-Incidence Scattering From A Diffraction Grating,
2010
Indiana University - Bloomington
Dynamical Theory Calculations Of Spin-Echo Resolved Grazing-Incidence Scattering From A Diffraction Grating, Rana Ashkar, P. Stonaha, A. L. Washington, V. R. Shah, M. R. Fitzsimmons, B. Maranville, C. F. Majkrzak, W. T. Lee, W. L. Schaich, Roger Pynn
Nebraska Center for Materials and Nanoscience: Faculty Publications
Neutrons scattered or reflected from a diffraction grating are subject to a periodic potential analogous to the potential experienced by electrons within a crystal. Hence, the wavefunction of the neutrons can be expanded in terms of Bloch waves and a dynamical theory can be applied to interpret the scattering phenomenon. In this paper, a dynamical theory is used to calculate the results of neutron spin-echo resolved grazing-incidence scattering (SERGIS) from a silicon diffraction grating with a rectangular profile. The calculations are compared with SERGIS measurements made on the same grating at two neutron sources: a pulsed source and a continuous …
Understanding The Promotion Effect: A Density Functional Theory Study Based On High Resolution Transmission Electron Microscopy Images For Mos2-Cobalt Promoted Interfaces,
2010
University of Texas at El Paso
Understanding The Promotion Effect: A Density Functional Theory Study Based On High Resolution Transmission Electron Microscopy Images For Mos2-Cobalt Promoted Interfaces, Manuel A. Ramos
Open Access Theses & Dissertations
Many studies had been done in order to understand promotion effect and structure/function in unsupported catalyst. Results indicated that d-electrons play an important role promoting catalytical active sites at the edges of MoS2 catalytically structures. Sulfur removal from crude oil, occurs on the edge of molybdenum di-sulfide (MoS2) nano structures, due to promotion of MoS2 nano structures with nickel or cobalt in sulfur-terminated or molybdenum-terminated edge planes. The promotion leads to formation of so-called CoMoS phase (MoS2/Co9S8) first discovered by meaning of Mössbauer spectroscopy, much more CoMoS phase usually called unsupported catalytical particles, have been topic of great interest in …
Spectroscopic Study Of The Inhibition Of Calcium Oxalate Calculi By Larrea Tridentata,
2010
University of Texas at El Paso
Spectroscopic Study Of The Inhibition Of Calcium Oxalate Calculi By Larrea Tridentata, Luis Alonso Pinales
Open Access Theses & Dissertations
The causes of urolithiasis include such influences as diet, metabolic disorders, and genetic factors which have been documented as sources that aggravate urinary calculi depositions and aggregations, and, implicitly, as causes of urolithiasis. This study endeavors to detail the scientific mechanisms involved in calcium oxalate calculi formation, and, more importantly, their inhibition under growth conditions imposed by the traditional medicinal approach using the herbal extract, Larrea tridentata. The calculi were synthesized without and with Larrea tridentata infusion by employing the single diffusion gel technique. A visible decrease in calcium oxalate crystal growth with increasing amounts of Larrea tridentata herbal infusion …
Protein Folding, Aggregation And Unfolding In Monte Carlo Simulations,
2010
Forschungszentrum Jülich (FZJ)
Protein Folding, Aggregation And Unfolding In Monte Carlo Simulations, Sandipan Mohanty, Anders Irbäck, Simon Mitternacht, Giorgio Favrin, U. H.E. Hansmann
Michigan Tech Publications, Part 1
An implicit water all-atom model is used to study folding, aggregation and mechanical unfolding of small proteins. Physically reasonable results obtained for a variety of applications indicate healthy global properties of the interaction potential.
An Ab-Initio Study Of The Elastic Properties Of Important Group Iv Diborides At High Temperatures,
2010
University of Texas at El Paso
An Ab-Initio Study Of The Elastic Properties Of Important Group Iv Diborides At High Temperatures, Manny Gonzales
Open Access Theses & Dissertations
Presented is an ab-initio Molecular Dynamics (MD) study, employing the Density Functional Theory (DFT), of the lattice parameter, thermal expansion coefficients and elastic constants of ZrB2, TiB2 and HfB2 as a function of temperature. The MD trajectories provide the equilibrium lattice parameters at finite temperatures, and the gradient of the energy from these equilibrium solutions is then used to calculate the components of the stiffness tensor. The results for ZrB2 are shown to agree well with reported experimental results for the lattice parameters and elastic constants as a function of temperature.
Pressure Induced Dynamical Instabilities In Body Center Cubic Crystals,
2010
University of Texas at El Paso
Pressure Induced Dynamical Instabilities In Body Center Cubic Crystals, Oscar Guerrero
Open Access Theses & Dissertations
Large-scale atomistic simulations of shock-wave propagation in single crystals exhibit large anisotropies in the elastic-plastic and solid-liquid transitions. Characteristic of this type of simulations are the large strains at which the crystal yields plastically, regardless of crystal orientation. At these large strains, uniaxial deformations, such as those produced in planar shock loading generate dynamical instabilities. We have investigated the directional anisotropy of the elastic limit in bcc crystals, in particular Tantalum (Ta), employing molecular dynamics (MD) simulations. We show that the elastic - plastic transition in BCC defect-free crystals is caused by the appearance of soft-phonon modes and not via …
Inelastic Collisions In Cold Dipolar Gases,
2010
University of Kentucky
Inelastic Collisions In Cold Dipolar Gases, Catherine A. Newell
University of Kentucky Doctoral Dissertations
Inelastic collisions between dipolar molecules, assumed to be trapped in a static electric field at cold (> 10−3K) temperatures, are investigated and compared with elastic collisions. For molecules with a Λ-doublet energy-level structure, a dipole moment arises because of the existence of two nearly degenerate states of opposite parity, and the collision of two such dipoles can be solved entirely analytically in the energy range of interest. Cross sections and rate constants are found to satisfy simple, universal formulas. In contrast, for molecules in a Σ electronic ground state, the static electric field induces a dipole moment in …
A Systematic Study Of The Dispersion Of Swnts In Organic Solvents,
2010
Technological University Dublin
A Systematic Study Of The Dispersion Of Swnts In Organic Solvents, Qiaohuan Cheng, Sourabhi Debnath, Luke O'Neill, Theresa Hedderman, Elizabeth Gregan, Hugh Byrne
Articles
Dispersions of as-produced HiPco single-walled carbon nanotubes (SWNTs) in a series of organic solvents were prepared by dilution with the aid of tip sonication. Mild centrifugation (~ 945 g) was carried out to remove large bundles. Atomic force microscopy (AFM) studies revealed that the bundle size decreased as the dispersion was diluted. By measuring the UV-vis-NIR absorption before and after centrifugation as a function of the concentration, the dispersion limit of SWNTs in each solvent can be determined. Correlations between the dispersion limit and solvent solubility parameters, including the Hildebrand solubility parameter and three dimensional Hansen solubility parameters, are explored, …
Excitation-Induced Germanium Quantum Dot Formation On Si (100)-(2×1),
2010
Old Dominion University
Excitation-Induced Germanium Quantum Dot Formation On Si (100)-(2×1), Ali Oguz Er, Hani E. Elsayed-Ali
Physics Faculty Publications
The effect of nanosecond pulsed laser excitation on the self-assembly of Ge quantum dots grown by pulsed laser deposition on Si (100)-(2×1) was studied. In situ reflection high-energy electron diffraction and ex situ atomic force microscopy were used to probe the quantum dot structure and morphology. At room temperature, applying the excitation laser decreased the surface roughness of the grown Ge film. With surface electronic excitation, crystalline Ge quantum dots were formed at 250 °C, a temperature too low for their formation without excitation. At a substrate temperature of 390 °C, electronic excitation during growth was found to improve the …
