UScholar Works
 
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CreatorTitleDescriptionSubjectDate
26 Saam, BrianAsymptotic and intermediate long-time behavior of nuclear free induction decays in polycrystalline solids and powdersFree induction decay (FID) measured by nuclear magnetic resonance (NMR) in a polycrystalline solid is the isotropic average of the FIDs for individual single crystallites. It has been recently proposed theoretically and verified experimentally that the long-time behavior of single-crystal FIDs has t...2012-01-01
27 Rogachev, AndreySuperconductor-insulator transition in long MoGe nanowires2012-01-01
28 Mishchenko, EugeneSpin and charge structure of the surface states in topological insulatorsWe investigate the spin and charge densities of surface states of the three-dimensional topological insulator Bi2Se3, starting from the continuum description of the material [Zhang et al., Nat. Phys. 5, 438 (2009)]. The spin structure on surfaces other than the (111) surface has additional complexit...2012-01-01
29 Wu, Yong-ShiGround-state degeneracy in the Levin-Wen model for topological phasesWe study the properties of topological phases by calculating the ground-state degeneracy (GSD) of the two-dimensional Levin-Wen (LW) model. Here it is explicitly shown that the GSD depends only on the spatial topology of the system. Then we show that the ground state on a sphere is always nondegener...2012-01-01
30 Gerton, JordanEffect of magnetic Gd impurities on the superconducting state of amorphous Mo-Ge thin films with different thickness and morphologyWe studied the effect of magnetic doping with Gd atoms on the superconducting properties of amorphous Mo70Ge30 films. We observed that in uniform films deposited on amorphous Ge, the pair-breaking strength per impurity strongly decreases with film thickness initially and saturates at a finite value ...2012-01-01
31 Lupton, John MarkExciton storage in CdSe/CdS tetrapod semiconductor nanocrystals: electric field effects on exciton and multiexciton statesCdSe/CdS nanocrystal tetrapods are interesting building blocks for excitonic circuits, where the flow of excitation energy is gated by an external stimulus. The physical morphology of the nanoparticle, along with the electronic structure, which favors electron delocalization between the two semicond...2012-01-01
32 Lupton, John MarkSlow hopping and spin dephasing of coulombically bound polaron pairs in an organic semiconductor at room temperaturePolaron pairs are intermediate electronic states that are integral to the optoelectronic conversion process in organic semiconductors. Here, we report on electrically detected spin echoes arising from direct quantum control of polaron pair spins in an organic light-emitting diode at room temperature...2012-01-01
33 Lupton, John MarkProbing the electrode-polymer interface in conjugated polymer devices with surface-enhanced Raman scatteringA crucial consideration in organic devices is the role of the interface between a metal electrode and the active polymer material. Here, we use the conjugated polymer poly[2-methoxy-5-(2-ethylhexyl-oxy)-1,4-phenylene-vinylene] (MEH-PPV) with model gold and silver electrodes to perform surface-enhanc...2012-01-01
34 Kieda, David B.; Binks, Joshua ThomasGamma-ray emission by the BL Lac Markarian 501Optical astronomy is the study of the heavens as they emit light, or the visible portion of the electromagnetic spectrum. Gamma-ray astronomy is the study of astrophysical sources that emit the most energetic form of electromagnetic radiation (ie: gamma-rays). High Energy gamma-rays are much too f...Markarian 501; Gamma-ray emission; Trapeze Interactive Poster2010-03-15
35 Vardeny, Zeev ValentinePhotoexcitation dynamics in polythiophene/fullerene blends for photovoltaic applicationsWe used the transient and steady state photomodulation spectroscopies for studying the photoexcitations dynamics in blends of regio-regular poly(3-hexylthiophene) (RR-P3HT) and fullerene in a broad spectral range from 0.15 to 2.25 eV. We found that both localized polarons and singlet excitons are in...2012-01-01
36 Gondolo, PaoloAxion cold dark matter in nonstandard cosmologiesWe study the parameter space of cold dark matter axions in two cosmological scenarios with nonstandard thermal histories before big bang nucleosynthesis: the low-temperature reheating (LTR) cosmology and the kination cosmology. If the Peccei-Quinn symmetry breaks during inflation, we find more allow...2010-01-01
37 Saam, BrianComment on pressure dependence of wall relaxation in polarized 3He gaseous cellsZheng et al. [Zheng, Gao, Ye, and Zhang, Phys. Rev. A 83, 061401(R) (2011)] have measured a strong linear pressure dependence of the nuclear relaxation rate of 3He in glass cells typically used to generate and/or store polarized 3He at room and cryogenic temperatures. Their interpretation is that th...2012-01-01
38 Gondolo, PaoloLight dark matter in leptophobic Z' modelsRecent experimental results in direct dark matter detection may be interpreted in terms of a dark matter particle of mass around 10 GeV=c2. We show that the required scenario can be realized with a new dark matter particle charged under an extra Abelian gauge boson Z0 that couples to quarks but not ...2012-01-01
39 Saam, BrianPhase relationship between the long-time beats of free induction decays and spin echoes in solidsRecent theoretical work on the role of microscopic chaos in the dynamics and relaxation of many-body quantum systems has made several experimentally confirmed predictions about the systems of interacting nuclear spins in solids, focusing in particular on the shapes of spin echo responses measured by...2012-01-01
40 Gondolo, PaoloHalo independent comparison of direct dark matter detection dataWe extend the halo-independent method of Fox, Liu, and Weiner to include energy resolution and efficiency with arbitrary energy dependence, making it more suitable for experiments to use in pre-senting their results. Then we compare measurements and upper limits on the direct detection of low mass (...2012-01-01
41 Bromley, Benjamin C.Binary disruption by massive black holes: hypervelocity stars, S stars, and tidal disruption eventsWe examine whether disrupted binary stars can fuel black hole growth. In this mechanism, tidal disruption produces a single hypervelocity star (HVS) ejected at high velocity and a former companion star bound to the black hole. After a cluster of bound stars forms, orbital diffusion allows the black ...2012-01-01
42 Gondolo, PaoloDark stars: BegynnelsenThe first phase of stellar evolution in the history of the universe may be Dark Stars, powered by dark matter heating rather than by fusion. Weakly interacting massive particles, which are their own antiparticles, can annihilate and provide an important heat source for the first stars in the univers...Dark stars; WIMP; Weakly interacting massive particles; Annihilations2009
43 Ailion, David CharlesNuclear magnetic resonance study of diffusion of bound and free fluorine interstitials in alkaline earth fluorides doped with trivalent impuritiesWhen alkaline-earth fluorides are doped with trivalent impurities, interstitial fluorines are created to maintain charge neutrality. We have performed NMR dipolar-energy relaxation measurements over a wide temperature range and have observed the diffusion of both free and locally bound fluorine inte...Diffusion; Motion; Crystals; NMR; Fluorine1979
44 Vardeny, Zeev Valentine; Nahata, AjayResonantly-enhanced transmission through a periodic array of subwavelength apertures in heavily-doped conducting polymer filmsWe observed resonantly-enhanced terahertz transmission through two-dimensional (2D) periodic arrays of subwavelength apertures with various periodicities fabricated on metallic organic conducting polymer films of polypyrrole heavily doped with PF6 molecules [PPy(PF6)]. The"anomalous transmission" s...Resonantly enhanced transmission; Subwavelength apertures; Polypyrrole; PPy(PF6)2006
45 Mattis, Daniel C.Extinction of antiferromagnetism by holes in CuO2The introduction of a sufficient number of holes into antiferromagnetic planes of Cu02 in La-Cu-O and Y-Ba-Cu-O causes antiferromagnetism to disappear at a critical density xc, beyond which superconductivity occurs. We investigate two competing tendencies, which determine the dependence of xc on the...Antiferromagnets1991-08
46 Vardeny, Zeev Valentine; Ehrenfreund, Eitan A.Linear and nonlinear photoexcitation dynamics in ∏-conjugated polymersLinear and nonlinear recombination kinetics with various lifetime distributions were identified for long-lived photoexcitations in a series of rr-conjugated polymer films using modulation frequency and excitation intensity dependencies of the photoinduced absorption. This includes monomolecular, bim...Linear photoexcitation; Nonlinear photoexcitation; pi-conjugated polymers; Recombination kinetics2003-01
47 DeTar, CarletonPotts flux tube model at nonzero chemical potentialWe model the deconfinement phase transition in quantum chromodynamics at nonzero baryon number density and large quark mass by extending the flux tube model ~three-state, three-dimensional Potts model! to nonzero chemical potential. In a direct numerical simulation we confirm mean-field-theory pre...Phase transitions; Quark-gluon plasma; Chemical potential; Potts model2000-03
48 Vardeny, Zeev ValentinePolarization memory decay spectroscopy of photoexcitations in ∏-conjugated polymers: evidence for excimersWe used the technique of ultrafast transient polarized photomodulation in the visible/near-infrared range and polarization memory decay (PMD) spectroscopy to study the primary photoexcitations in films and solutions of two poly(phenylene-vinylene) (PPV) derivatives, namely, 2-methoxy-5-(2'-ethylhex...Photoexcitations; pi-conjugated polymers; Polarization memory decay spectroscopy; PMD; DOO-PPV; MEH-PPV; Ultrafast transient polarized photomodulation; Intrachain singlet excitons; Excimers; Interchain charge transfer exciton2008-05
49 Gondolo, PaoloImproved constraints on supersymmetric dark matter from muon g-2The new measurement of the anomalous magnetic moment of the muon by the Brookhaven AGS experiment 821 again shows a discrepancy with the standard model value. We investigate the consequences of these new data for neutralino dark matter, updating and extending our previous work [E. A. Baltz and P. ...Magnetic moment; Neutralinos2003-03
50 Wu, Yong-ShiOpen spin chain and open spinning stringIn this letter, we study the open spinning strings and their SYM duals. A new class of folded open spinning strings is found. At planar one-loop level in SYM, by solving the thermodynamic limit of the Bethe ansatz equations for an integrable open spin chain, we find good agreement with string theory...2004-07
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