UScholar Works
 
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CreatorTitleDescriptionSubjectDate
151 Vardeny, Zeev ValentineDetection of electronic excited states in conjugated polymers by picosecond transient strain spectroscopyWe describe a new type of spectroscopy based on picosecond transient strain in absorption photomodulation that can be used to detect and identify both allowed and forbidden optical transitions in solid thin films. We have applied the new spectroscopy to a variety of conducting polymer films such as ...Picosecond transient strain spectroscopy1995-02
152 Vardeny, Zeev ValentineMagneto-optical studies of photoexcitations in C61We have used a variety of cw optical and optically detected magnetic-resonance techniques to characterize long-lived photoexeitations in methanofullerene (C6 1) as a dispersion in polystyrene glass, at temperatures below 10 K. We identify triplet excitons with zero-field-splitting (ZFS) parameters...Photoexcitations; C61; Methanofullerene1993-12
153 Wu, Yong-ShiRemarks on fractional statisticsSome issues in the theory of fractional (or intermediate) statistics are discussed with an eye on possible applications to the quantum Hall effect: spins and statistics of clusters, invariant characterization of statistics, and the effect of space topology.Fractional statistics1985-01
154 Kieda, David B.High resolution charge measurements of UH cosmic ray nuclei using a direct imaging Cherenkov ground-based observatoryThe accurate determination of the elemental composition of cosmic rays at high energies is expected to provide crucial clues on the origin of these particles. Here we discuss a technique that has become possible through the use of modern ground-based Cherenkov imaging detectors. We combine a measure...Cherenkov light; Quark star; UH nuclei; Magnetic monopole2003
155 Mishchenko, Eugene; Raikh, Mikhail E.Electrostatics of straight and bent single-walled carbon nanotubesResponse of a single-walled carbon nanotube to external electric field, F, is calculated analytically within the classical electrostatics. Field-induced charge density distribution is approximately linear along the axis of a metallic nanotube and depends rather weakly, as ln(h/ r), on the nanotube...Electrostatics2006-10
156 Symko, Orest GeorgeExchange interactions and magnetic dimension in Cu(L-alanine)2A study of the magnetic properties of the copper (II) complex of the amino acid L-alanine [CU(Lalanine) 2] is reported. The susceptibility of a powder sample has been measured between 0.013 and 240 K. A linear-spin-chain model with antiferromagnetic exchange coupling J = -0.52 K fits well the susce...Cu(L-alanine)2; Exchange interactions; Magnetic dimension1991-01
157 Rogachev, AndreyDetermination of the superconductor-insulator phase diagram for one-dimensional wiresWe establish the superconductor-insulator phase diagram for quasi-one-dimensional wires by measuring a large set of MoGe nanowires. This diagram is roughly consistent with the Chakravarty-Schmid-Bulgadaev phase boundary, namely, with the critical resistance being equal to RQ ¼ h=4e2. Deviations fr...One-dimensional wires; Superconductor-insulator phase diagram; MoGe; Chakravarty-Schmid-Bulgadaev; Phase boundary2008-11
158 Ailion, David Charles; Morris, Alan H.Asymmetric spin echo sequences. a simple new method for obtaining NMR 1H spectral imagesThe nuclear magnetic resonance (NMR) signal decay produced by reversible tissue-induced dephasing of the magnetization components in the transverse plane (reversible tissue-induced dephasing) was measured and expressed as a function of a new transverse relaxation time T'2 (T2 prime) for samples of ...Asymmetric spin echo; Signal decay; Chemical shift; Tissue characterization; Lung aeration; Fatty liver1985
159 DeTar, CarletonQuenched hadron spectroscopy with improved staggered quark actionWe investigate light hadron spectroscopy with an improved quenched staggered quark action. We compare the results obtained with an improved gauge plus an improved quark action, an improved gauge plus standard quark action, and the standard gauge plus standard quark action. Most of the improvement ...Staggered quarks; Chiral symmetry; Flavor symmetry1998-07
160 Vardeny, Zeev ValentineDirectional emission from asymmetric microlaser resonators of ∏-conjugated polymersA ∏-conjugated polymer film was fabricated into an asymmetric microlaser resonator having a quadrapole deformation with irregular boundaries and a Q factor of 600. At high excitation intensities above the threshold for lasing, we observed multimode laser emission spectra and directional emission a...Directional emission; Asymmetric microlaser resonators; pi-conjugated polymers; DOO-PPV; poly(dioctyloxy) phenylene vinylene2004
161 Wu, Yong-ShiSuppression of local degrees of freedom of gauge fields by chiral anomaliesA path-integral quantization is presented for the chiral Schwinger model on a Riemann surface. Gauge invariance is maintained by integrating over all gauge potentials without the usual gauge fixing. All local degrees of freedom of the gauge field are suppressed after the integration of the anomalous...Chiral anomalies; Degrees of freedom1990-08
162 Mattis, Daniel C.; Paul, PrabasajStatistical transfer matrix of a spin-glass ladderThis work concerns the Edwards-Anderson Ising model of a spin ladder, in which random bonds +_J connect nearest-neighbor Ising spins. We calculate the exact free energy of the quenched, frustrated, spin-glass-like ladder as an integral over a probability distribution P(x), the eigenfunction of a s...Thermodynamics; Ising1999
163 DeTar, CarletonExotic mesons in quenched lattice QCDSince gluons in QCD are interacting fundamental constituents just as quarks are, we expect that in addition to mesons made from a quark and an antiquark, there should also be glueballs and hybrids ~bound states of quarks, antiquarks, and gluons!. In general, these states would mix strongly with th...Hybrid mesons; Antiquarks1997-12
164 Saam, BrianWall relaxation of 3He in spin-exchange cellsThe 3He longitudinal spin-relaxation rate T1-1 is crucial for production of highly polarized 3He by spin-exchange optical pumping. We show that T1-1 is increased by a factor of 2-20 solely by exposure of spin-exchange cells to a few-kG magnetic field. The original T1-1 can be restored by degaussing ...Wall relaxation; Spin-exchange cells; 3He; Longitudinal spin-relaxation; Spin-exchange optical pumping; SEOP; Hyperpolarized 3He; Surface magnetism; Glass cells2001-09
165 Vardeny, Zeev ValentineOptical studies of metallodielectric photonic crystals: bismuth and gallium infiltrated opalsWe have fabricated three-dimensional metallodielectric photonic crystals that consist of bismuth and gallium metals infiltrated into porous synthetic opals that have 300 nm diam silica balls. The specular reflectivity was measured in a broad spectral range from 0.3 to 25 mm using a variety of light ...Metallodielectric photonic crystals; Bismuth infiltrated opals; Gallium infiltrated opals; Bragg; Porous synthetic opals2004
166 Vardeny, Zeev ValentineSpecific heats and lattice dynamics of cuprous halidesThe specific heats Cp(T) of CuCl, CuBr, and Cul were measured by the adiabatic calorimetric technique. The corresponding Debye temperature for each crystal is given and a comparison between the results is drawn. The room-temperature phonon dispersion relations for these cystals are fitted by a nine...Cuprous halides; CuBr; CuCl; CuI1978-10
167 Wu, Yong-ShiNear-horizon Virasoro symmetry and the entropy of de Sitter space in any dimensionDe Sitter spacetime is known to have a cosmological horizon that enjoys thermodynamic-like properties similar to those of a black hole horizon. In this note we show that a universal argument can be given for the entropy of de Sitter spacetime in arbitrary dimensions, by generalizing a recent near ho...1999-05
168 Symko, Orest GeorgeSize considerations in interfacing thermoacoustic coolers with electronicsSmall thermoacoustic coolers heat pumps show much promise for heat management in microcircuits, especially since they can be miniaturized for interfacing with circuits. Usually they are operated in the resonant mode with sound pumping heat; the device dimensions are reduced when the acoustic pump fr...Thermoacoustic coolers; Heat management; Microcircuits; Miniturization2002
169 Vardeny, Zeev ValentineHigh-pressure study of picosecond exciton dynamics in solid C60We have studied the singlet exciton decay by picosecond photoinduced absorption in films of Qo, under pressures up to 62 kbar. The picosecond decay of excitons excited in the absorption tail continues to be dominated by broad distributions of lifetimes at high pressure. These results suggest that th...Picosecond exciton dynamics; Solid C601994-08
170 Williams, Clayton C.Evidence of internal fields in two-variant ordered GaInP2 by near-field scanning optical microscopyGaInP2 is studied in cross section with the scanning capacitance and near-field scanning optical microscope. Our study shows significant differences in the electronic and optical properties between ordered single- and two-variant GaInP2. In single-variant samples, spatially uniform capacitance signa...Photoluminescence; GaInP2; Microscopy; Electrical fields1997
171 Mishchenko, EugeneMesoscopic spin-Hall effect in 2D electron systems with smooth boundariesThe spin-Hall effect in a ballistic 2D electron gas with Rashba-type spin-orbit coupling and smooth edge confinement is studied. We predict that the interplay of semiclassical electron motion and quantum dynamics of spins leads to several distinct features in spin density along the edge that origina...Spin- Hall effect; 2D electron systems2009-05
172 Symko, Orest GeorgeDoes the quasicrystal AlCuFe follow Ohm's law?We present the first measurements of the electrical I-V characteristics of AlCuFe quasicrystalline thin films processed by solid state interdiffusion of magnetron sputtered Al, Cu, and Fe layers. Despite the peculiar electronic properties of quasicrystals, our results show that those samples follow ...AlCuFe; Quasicrystal1994-10
173 Sokolsky, PierreEnergy estimation of UHE cosmic rays using the atmospheric fluorescence techniqueWe use the CORSIKA air shower simulation program to review the method for assigning energies to ultra-high energy (UHE) cosmic rays viewed with the air fluorescence technique. This technique uses the atmosphere as a calorimeter, and we determine the corrections that must be made to the calorimetric ...Fluorescence; Energy estimation; Ultra-high energy cosmic rays2000-08
174 DeTar, CarletonHigh-precision lattice QCD confronts experimentThe recently developed Symanzik-improved staggered-quark discretization allows unquenched lattice-QCD simulations with much smaller (and more realistic) quark masses than previously possible. To test this formalism, we compare experiment with a variety of nonperturbative calculations in QCD draw...Staggered quarks2004-01
175 Mattis, Daniel C.Tricritical point in random-field Ising modelThe numerical investigation of the random-field Ising model by Houghton, Khurana, and Seco1 has revealed a number of interesting features concerning the three-dimensional Ising model in a random external field Bt. Earlier, Aharony2 had already found that even in a mean-field approximation the b...Random external field; Tricritical points; Gaussian distribution1985
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