UScholar Works
 
Filters: Department: "Physics" Collection: "ir_uspace"
101 - 125 of 924
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CreatorTitleDescriptionSubjectDate
101 Saam, Brian; Pugmire, Ronald J.Gas-phase spin relaxation of 129XeWe have completed an extensive study of 129Xe longitudinal spin relaxation in the gas phase, involving both intrinsic and extrinsic mechanisms. The dominant intrinsic relaxation is mediated by the formation of persistent Xe2 van der Waals dimers. The dependence of this relaxation on applied magnetic...129Xe; Gas-phase spin relaxation2008-10
102 Vardeny, Zeev ValentineUltrafast dynamics in metallic and semiconducting carbon nanotubesTransient polarized pump/probe transmission changes upon pulse photoexcitation at 1.6 eV were measured in chiral enriched carbon nanotubes ensembles of both metallic and semiconductor characters, in a very broad probe spectral range from mid-IR to visible, combining several ultrafast laser systems...2009-11
103 Symko, Orest GeorgeApplication of SQUID magnetometer to nuclear magnetic thermometryThis paper presents an application of a SQUID magnetometer for low temperature thermometry using the magnetic properties of a nuclear paramagnet. The static magnetization of a material which obeys Curie's law provides a very sensitive means of thermometry. Also included in the device is the capabi...SQUID magnetometer; Nuclear magnetic thermometry; Low temperature thermometry1976
104 Lupton, John MarkStimulated emission depletion of triplet excitons in a phosphorescent organic laserTriplet formation is investigated in an optically pumped polymer laser by detecting the phosphorescence emission after excitation. A clear correlation is observed between the onset of lasing and a saturation of phosphorescence intensity due to stimulated emission depletion of the singlet state and t...Triplet excitons; Triplet formation; Emission depletion; Phosphorescent organic laser; Optically pumped polymer laser2006
105 Kieda, David B.; Gaisser, Thomas K.; Sokolsky, PierreCosmic-ray composition around 10^18 eVWe use the depth of maximum distribution as measured by the stereo Fly's Eye detector to study the chemical composition of the primary cosmic radiation between 3x 1017 eV and 1019 eV. The analysis depends on the use of simulations to study the response of the detector as well as sensitivity to assum...Fly's Eye; Cosmic ray composition; Cosmic ray nuclei; Chemical composition1993-03
106 DeTar, CarletonfB quenched and unquenchedResults for fβ, / fβs, /fD, /fDs , and their ratios are presented. High statistics quenched runs at β = 5.7, 5.85, 6.0, and 6.3, plus a run still in progress at β = 6.52 make possible a preliminary extrapolation to the continuum. The data allows good control of all systematic errors except for q...Decay constants; Wilson quarks1996-03
107 Lupton, John MarkUltrafast dynamics of charge carrier photogeneration and geminate recombination in conjugated polymer: fullerene solar cellsWe investigate the nature of ultrafast exciton dissociation and carrier generation in acceptor-doped conjugated polymers. Using a combination of two-pulse femtosecond spectroscopy with photocurrent detection, we compare the exciton dissociation and geminate charge recombination dynamics in blends ...Ultrafast dynamics; Charge carrier photogeneration; Geminate recombination; Exciton dissociation; Acceptor-doped; MeLPPP; MDMO-PPV2005-11
108 Symko, Orest GeorgeAbsorption at radio frequencies in superconducting Y1Ba2Cu3OyThe large magnetic-field-dependent ac absorption in superconducting Y1Ba2Cu3Oy ceramics and powders decreases slowly with increasing frequency in the range 2-16 MHz. The magnetic-field-dependent ac absorption is observed below Tc in superconducting Y1Ba2Cu3Oy ceramics, powders and twinned crystals ...Copper-octahedral oxygen perovskites; Superconducting Y1Ba 2Cu3Oy; ac absorption1989
109 Vardeny, Zeev ValentineElectromodulated photoinduced absorption; a new spectroscopy in ∏-conjugated polymer/C60-blendsWe have applied the electromodulated photoinduced absorption (EPA) technique to a variety of C 6 0 -doped and pristine luminescent conducting polymer films. EPA measures the electric field-related change of the absorption in the sample as a result of above-gap illumination. An electric field leads t...Electromodulated photoinduced absorption; EPA; C60 doping; Electromodulated photoluminescence; EPL; Polaron pair polarizability1997
110 Gondolo, PaoloDetectability of weakly interacting massive particles in the Sagittarius dwarf tidal streamTidal streams of the Sagittarius dwarf spheroidal galaxy (Sgr) may be showering dark matter onto the solar system and contributing ~(0:3-23)% of the local density of our galactic halo. If the Sagittarius galaxy contains dark matter in the form of weakly interacting massive particles (WIMPs), the ext...WIMP; Weakly interacting massive particles; Sagittarius dwarf galaxy; Recoil energy; Sgr stream2005-02
111 Vardeny, Zeev ValentinePhotophysics of pristine and C60-doped disubstituted polyacetyleneUsing a variety of steady-state spectroscopies we studied the long-lived photoexcitations and electronic excited states of poly disubstituted acetylene (PDPA-nBu), the backbone structure of which is a disubstituted trans-polyacetylene, as well as PDPA-nBu/C60 blends. The cw spectroscopies include a...Photophysics; Pristine disubstituted polyacetylene; C60-doped disubstituted polyacetylene; pi-conjugated polymers; Photoexcitations; Electronic excited states2002-08
112 DeTar, CarletonConjecture concerning the modes of excitation of the quark-gluon plasmaIt is a widely held belief that at temperatures much higher than the confinement scale of quantumchromodynamics (QCD), quarks and gluons become free, giving rise to a new form of matter, called the quark-gluon plasma. It is conjectured here that the characterization of the plasma as a free or weakl...Polyakov loops; Excitation1985-07
113 Vardeny, Zeev ValentinePhotocarrier dynamics in compensated hydrogenated amorphous siliconThe photocarrier dynamics in compensated a-Si:H is studied using the time-dependent photomodulation technique in the subpicosecond-to-millisecond time range. We find that photocarriers are quickly trapped in shallow impurity levels for t < 10 psec, similar to the behavior in singly doped materials...Photocarriers; a-Si:H; Amorphous silicon; Fast trapping1986-03
114 Vardeny, Zeev ValentineAmplified spontaneous emission and lasing in conducting polymers and fluorescent dyes in opals as photonic crystalsSpectral narrowing of photoluminescence (PL) and evolution of sharp emission lines upon optical excitation have been observed in opals made of SiO2 spheres infiltrated with conducting polymers such as OOPPV and MDDOPPV and also fluorescent dyes such as rhodamine 6G, NK-3483, and coumarin 120. Their ...Amplified spontaneous emission; Lasing; Fluorescent dyes1999
115 Wu, Yong-ShiTwo-loop analysis of non-Abelian Chern-Simons theoryPerturbative renormalization of a non-Abelian Chern-Simons gauge theory is examined. It is demonstrated by explicit calculation that, in the pure Chern-Simons theory, the & function for the coefficient of the Chern-Simons term vanishes to three-loop order. Both dimensional regularization and regula...Chern-Simons theory; Yang-Mills theory; Regularization1992-12
116 Ailion, David Charles14N study of the role of N-D---O bonds in the deuteron glass transition14N spin-lattice relaxation-time measurements in Rb0.28(ND4)0.72D2PO4 provide direct evidence for the fast exchange averaging of the "long" and "short" N-D---O hydrogen bonds between the ND4 group and the four surrounding PO4 groups. This exchange and the associated distortion of the ND4 tetrahedron...NMR; Hydrogen bonds; Spin-lattice; Relaxation-time; Deuteron glass1999
117 Vardeny, Zeev ValentineStudies of polymer microring lasers subject to uniaxial stressThe emission spectra of microring lasers fabricated from ∏-conjugated polymer films casted on nylon microfibers with diameters in the range of 35-90 µm were studied upon application of uniaxial stress with strain up to ~12%. The laser emission spectra substantially change with the applied stress,...pi-conjugated polymers; Microring lasers; Uniaxial stress; DOO-PPV2007
118 Williams, Clayton C.Two step dopant diffusion study performed in two dimensions by scanning capacitance microscopy and TSUPREM IVWe report the results of a two-step two- dimensional (2D) diffusion study by scanning capacitance microscopy (SCM) and 2D SUPREM IV process simulation. A quantitative 2D dopant profile of a gate-like structure is measured with the SCM on a cross-sectioned polished silicon wafer. The gate-like struct...Scanning capacitance microscopy; SCM; Doping1998
119 Wu, Yong-ShiOne-loop shift in noncommutative Chern-Simons couplingIn this paper we study the one-loop shift in the coupling constant in a noncommutative pure U(N) Chern-Simons gauge theory in three dimensions. The one-loop shift is shown to be a constant proportional to N, independent of noncommutativity parameters, and non-vanishing for U(1) theory. Possible phy...2001-01
120 Gerton, JordanScattering of plasmons at the intersection of two metallic nanotubes: implications for tunnelingWe study theoretically the plasmon scattering at the intersection of two metallic carbon nanotubes. We demonstrate that, for a small angle of crossing θ « 1, the transmission coefficient is an oscillatory function of θ / λ, where ω is the interaction parameter of the Luttinger liquid in an ind...2008-12
121 Vardeny, Zeev ValentineResonant-Raman-scattering studies of disorder in solution-cast polydiacetylene filmsThe disorder in polydiacetylene films cast from solution is studied by Raman scattering under preresonance and resonance conditions in both Stokes and anti-Stokes configurations. The disorder-induced inhomogeneities in the exciton energy levels and the strongly coupled vibrations cause strong disper...Polydiacetylene films; Stokes configuration1990-08
122 Lupton, John MarkTime delayed electroluminescence overshoot in single layer polymer light-emitting diodes due to electrode luminescence quenchingWe investigate the transient response of single layer polymer light-emitting diodes (LEDs) based on poly[2-methoxy, 5-(2'ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV). An electroluminescence overshoot is observed between 1 and 2 μs after turning off the voltage pulse, depending on temperature...MEH-PPV; Delayed electroluminescence; Overshoot; Single layer; Electrode luminescence quenching; Transient responses2001
123 Gondolo, PaoloImplications of muon anomalous magnetic moment for supersymmetric dark matterThe anomalous magnetic moment of the muon has recently been measured to be in conflict with the standard model prediction with an excess of 2.6s. Taking the excess at face value as a measurement of the supersymmetric contribution, we find that at 95% confidence level it imposes an upper bound of 50...Magnetic moment; Neutralinos2001-05
124 Vardeny, Zeev ValentineSymmetric light emitting divices from poly(p-di ethynylene phenylene) (p-di phenylene vinylene) derivativesLight emitting devices were fabricated from 2,5-dialkoxy derivatives of poly(p-di ethynylene phenylene-p-di phenylene vinylene) (PDEPDPV) sandwiched between indium tin oxide (ITO) and Al. The current-voltage (Iel-V) curve, electroluminescence (EL) intensity-voltage (IEL-V) curve, and the EL spectra ...Poly(p-di ethynylene phenylene); PPV; Pi-conjugated polymers1995
125 Dawson, KyleRadiation tolerance of high-resistivity LBNL CCDsThick, fully-depleted p-channel charge-coupled devices (CCDs) have been developed at the Lawrence Berkeley National Laboratory (LBNL). These CCDs have several advantages over conventional n-channel CCDs, including enhanced quantum efficiency and reduced fringing at near-infrared wavelengths, a smal...P-Channel CCDs; Astrophysics instrumentation; Space instrumentation; SNAP satellite; Space-based telescopes2006-10
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