UScholar Works
 
Filters: Department: "Physics" Collection: "ir_uspace"
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CreatorTitleDescriptionSubjectDate
1 Vardeny, Zeev ValentineAbsorption studies of charged excitations in α-sexithiopheneWe present photoexcitation studies of vacuum deposited neutral films of α,ω-substituted sexithiophene (α-6T) using photoinduced absorption (PA) and PAdetected magnetic resonance spectroscopy (PADMR). We find evidence for photoinduced polarons having spin 1/2, with two absorption bands at 0.80...alpha- sexithiophene; Charged excitations; Photoexcitation; Photoinduced absorption1996
2 Williams, Clayton C.Evidence for internal electric fields in two variant ordered GaInP obtained by scanning capacitance microscopySingle and two variant ordered GaInP samples are studied in cross section with the scanning capacitance microscope. Our study shows significant differences in the electronic properties of single and two variant GaInP. In unintentionally doped, ordered two variant samples, both n and p-type like do...GaInP2; Atomic ordering; Internal electric fields; Scanning capacitance microscope1996
3 Williams, Clayton C.Nanometer scale absorption spectroscopy by near-field photodetection optical microscopyNear-field photodetection optical microscopy (NPOM) is a fundamentally new approach to near-field optical microscopy. This scanning probe technique uses a nanometer-scale photodiode detector which absorbs optical power directly as it is scanned in the near field of an illuminated sample surface. ...Near-field photodetection optical microscopy; NPOM; Nanoscale; Photodiode1996
4 Mattis, Daniel C.New mapping for particles on lattices with hard-core interactionsA novel mapping between Hilbert spaces of unequal dimensionalities yields many-body states which exactly satisfy the no-double-occupancy constraints for particles on lattices in arbitrary spatial dimensions. After proving the states are complete, we apply them to Nagaoka's theorem and the t-J model...Ferromagnetism; Spin; Dimensions1996
5 Vardeny, Zeev ValentineOptically detected magnetic resonance studies of undoped a-Si:HPhotogenerated carrier dynamics in undoped a-Si:H have been studied by photoinduced absorption (PA), photoluminescence (PL) and their respective optically detected magnetic resonances: PADMR and PLDMR. We have detected for the first time the "g = 4" resonance in PADMR in addition to the previously ...Undoped a-Si:H; Amorphous silicon; Carrier dynamics1996
6 Vardeny, Zeev ValentinePhotoexcitation dynamics in C60-doped PPV under bias illuminationWe have studied photoexcitation dynamics in pristine and C60-doped PPV films under bias Olumination by photoinduced absorption (PA), optically-detected magnetic resonance (ODMR), and electromodulated PA (EPA). Intrachain polaron pair species are the dominant excitations under these conditions. The p...Photoexcitation dynamics; C60-doped PPV; Bias illumination; PPV films; Photoinduced absorption; ODMR; Electroabsorption1996
7 Vardeny, Zeev ValentineAbsorption-detected magnetic-resonance studies of photoexcitations in conjugated-polymer/C60 compositesPhotoexcitations in poly[2-methoxy-5-(2'-ethyl-hexyloxy -p-phenylene vinylene] (MEH-PPV) and composites of MEH-PPV and C60 (MEH-PPV/C60) were studied by photoinduced absorption and absorptiondetected magnetic-resonance spectroscopies. We report direct evidence that the prominent triplet photoexci...Photoexcitations; Conjugated-polymer/C60 composites; Triplet photoexcitations1996-02
8 DeTar, CarletonContinuum limit in the quenched approximationPrevious work at G/g2 = 5.7 with quenched staggered quarks is extended with new calculations at 5.85 and 6.15 on lattices up to 323 x 64. These calculations allow a more detailed study of extrapolation in quark mass, finite volume and lattice spacing than has heretofore been possible. We discuss h...Decay constants; Staggered quarks; Wilson quarks1996-03
9 Williams, Clayton C.; Huang, YufengDirect comparison of cross-sectional scanning capacitance microscope dopant profile and vertical secondary ion-mass spectroscopy profileThe scanning capacitance microscope (SCM) has been shown to be useful for quantitative 2D dopant profiling near the surface of silicon. An atomic force microscope is used to position a nanometer scale tip at a silicon surface, and local capacitance change is measured as a function of sample bias. A ...Oxide capacitance; Dopant profile; Oxide layer; Scanning capacitance microscopy1996-01
10 Mishchenko, EugeneElectronic Raman scattering in a magnetic fieldRaman scattering in a magnetic field is proposed as a possible method to solve the problem of whether the light scattering in high-Tc superconductors comes from conduction electrons or not. The electronic Raman light scattering in a magnetic field is studied theoretically. The semiclassical approa...Raman scattering1996-01
11 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
12 Wu, Yong-ShiHidden massive Dirac fermions in effective field theory for integral quantum Hall transitionsIntegral quantum Hall plateau transitions in a planar lattice system due to gap collapse can be described by an effective field theory with Dirac fermions. We discuss how to reproduce the correct integral values for the Hall conductance sxy before and after the plateau transition, which are dictat...Dirac fermions; Vorticities; Edge states; Hall conductance1996-08
13 Wu, Yong-ShiMutual exclusion statistics between quasiparticles in the fractional quantum Hall effectIn this paper we propose a new assignment for mutual exclusion statistics between quasielectrons and quasiholes in the fractional quantum Hall effect. In addition to providing numerical evidence for this assignment, we show that the physical origin of this mutual statistics is a novel hard-core co...Exclusion statistics1996-10
14 Wu, Yong-ShiMutual-exclusion statistics in exactly solvable models in one and higher dimensions at low temperaturesWe study statistical characterization of the many-body states in exactly solvable models with internal degrees of freedom. The models under consideration include the isotropic and anisotropic Heisenberg spin chains, the Hubbard chain, and a model in higher dimensions which exhibits the Mott metal-in...Exclusion statistics; Exclusons; Hubbard chain1996-08
15 DeTar, CarletonNt = 6 equation of state for two flavor QCDWe improve the calculation of the equation of state for two flavor QCD by simulating on Nt = 6 lattices at appropriate values of the couplings for the deconfinement/chiral symmetry restoration crossover. For amq = 0.0125 the energy density rises rapidly to approximately 1 GeV/fm3 just after the cro...Kogut-Susskind fermions; Quark-gluon plasma1996-03
16 Vardeny, Zeev ValentineOptically-detected magnetic-resonance study of triplet state dynamics in C70We present studies of fluorescence, phosphorescence, photoinduced absorption, and their respective optically detected magnetic resonance of C70 molecules dispersed in polystyrene glasses. Two distinct triplet excitons are identified with principle zero-field splitting parameters (D≈0.0089 and 0.0...Ttriplet state dynamics; C70; Polystyrene glasses1996-03
17 Wu, Yong-ShiQuantum group, Bethe ansatz equations, and Bloch wave functions in magnetic fieldsThe wave functions for a two-dimensional Bloch electron in uniform magnetic fields at the mid-band points are studied by exploiting a connection to the quantum group Uq(sl2): A linear combination of its generators gives the Hamiltonian. We apply both analytic and numerical methods to obtain and an...Bloch electron1996-04
18 Gerton, JordanSinglet s-wave scattering lengths of 6Li and 7LiPhotoassociation of ultracold lithium atoms into bound vibrational levels of the A 1Σu+ excited state is used to probe the X1Σg+ ground-state interaction potential of 6Li2 and 7Li2 . It had been predicted that the s-wave photoassociation signal strength would pass through a minimum as a function...1996-06
19 Vardeny, Zeev ValentineStudies of charged excitations in ∏-conjugated oligomers and polymers by optical modulationWe have studied photogenerated charged excitations in sexithiophene and a variety of p-conjugated polymers by photoinduced absorption (PA) and PA-detected magnetic resonance. We found distinct spin signatures for polarons and bipolarons, which enabled us to separate their contributions to the PA spe...Pi-conjugated oligomers; Pi-conjugated polymers; Charged excitations; Optical modulation; Spin signatures; Bipolarons; Photoexcitation1996-08
20 Williams, Clayton C.Two-dimensional scanning capacitance microscopy measurements of cross-sectioned very large scale integration test structuresScanning probe technology, with its inherent two-dimensionality, offers unique capabilities for the measurement of electrical properties on a nanoscale. We have developed a setup which uses scanning capacitance microscopy (SCM) to obtain electrical information of cross-sectioned samples while simul...Oxide capacitance; Dopant profile; Scanning capacitance microscopy1996-01
21 DeTar, CarletonTwo-flavor staggered fermion thermodynamics at Nt = 12We present results of an ongoing study of the nature of the high temperature crossover in QCD with two light fermion flavors. These results are obtained with the conventional staggered fermion action at the smallest lattice spacing to date, approximately 0.1 fm. Of particular interest are (1) a stu...Staggered fermions; Phase transitions; Polyakov loop1996-10
22 Williams, Clayton C.Direct imaging of SiO2 thickness variation on Si using modified atomic force microscopeFabrication techniques of metal-oxide-semiconductor ~(MOS) transistors have been improved very rapidly during the last several decades. With this trend, scaling down of MOS transistors is necessary to improve the speed of circuits and the packing density of discrete devices. Both lateral and vertic...Silicon dioxide; Oxide layer; Phosphorus ions; Oxide capacitance; Dopant profile1996-03-01
23 Stringfellow, Gerald B.; Williams, Clayton C.Spatial mapping of ordered and disordered domains of GaInP by near-field scanning optical microscopy and scanning capacitance microscopyImaging of topography, locally induced photoluminescence and Fermi-level pinning in adjacent ordered and disordered domains on a cleaved GaInP sample is performed using a near-field scanning optical microscope and scanning capacitance microscope at room temperature in air. Highly localized photolumi...Gallium Phosphides; Surface Structure; Photoluminescence1996-04-13
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