UScholar Works
 
Filters: Department: "Physics" Collection: "ir_uspace"
501 - 525 of 924
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CreatorTitleDescriptionSubjectDate
501 Ailion, David CharlesNuclear magnetic resonance in random fields: cluster formation and local dynamics of a deuteron glassNMR data show that the deuteron "pseudo spin-glass" transition in Rbi- X(ND4)*D2P04 is not just a simple kinetic slowing down process but is characterized by a gradual condensation of randomly polarized clusters as expected if we deal with a percolation transition in eigenstate space. The results pr...NMR; Nuclear magnetic resonance; Random fields; Spin lattice1986
502 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
503 Saam, Brian; Laicher, GernotNuclear spin relaxation of 129Xe due to persistent xenon dimersWe have measured longitudinal nuclear relaxation rates of 129Xe in Xe-N2 mixtures at densities below 0.5 amagats in a magnetic field of 8.0 T. We find that intrinsic spin relaxation in this regime is principally due to fluctuations in the intramolecular spin-rotation (SR) and chemical-shift-anisot...Nuclear spin relaxation; Xe129; Xenon dimmers2006-12
504 Wu, Yong-ShiNumerical study of the three-dimensional random-field Ising model at zero and positive temperatureIn this paper the three-dimensional random-field Ising model is studied at both zero temperature and positive temperature. Critical exponents are extracted at zero temperature by finite size scaling analysis of large discontinuities in the bond energy. The heat capacity exponent α is found to be n...Bond energies; Ground states2006-08
505 DeTar, CarletonO(2,1) decomposition of the equal-mass multipheripheral equation at t=0We extend the results of a group-theoretical analysis of the t=0 multiperipheral equation to the case t<0 for pairwise equal masses. Using variables discussed in a previous paper, we diagonalize the equation in the Bali-Chew-Pignotti (BCP) model with respect to the 0(2, 1) group and relate the solut...Multiperipheral model; Unitaries1970-05
506 Wu, Yong-ShiObservable effects of the quantum adiabatic phase for noncyclic evolutionIt is pointed out that, contrary to naive expectation, the gauge structure or Berry connection recently found in slowly varying quantum systems gives rise to observable effects even for noncyclic evolutions corresponding to open paths in parameter space. We propose to test such effects in muon spin ...Adiabatic phases; Noncyclic evolution; Eigenstates1988-12
507 Symko, Orest GeorgeObservation of a narrow pseudogap near the Fermi level of AlCuFe quasicrystalline thin filmsWe present the first experimental determination by tunneling spectroscopy of the density of states (DOS) close to the Fermi energy of AlCuFe quasicrystalline thin film samples. The measurements show that the Fermi level in a quasicrystal lies in a deep narrow pseudogap 60 m e V wide. Above an applie...AlCuFe; Quasicrystalline thin films; Pseudogap; Fermi level; Density of states; DOS1995-05
508 Vardeny, Zeev ValentineObservation of molecular vibrations in real timeIn a recent Letter Rosker, Wise, and Tang1 have reported ultrafast optical measurements on two large dye molecules, malachite green and nile blue 690. Using the transmission-correlation technique with 40-fs light pulses, they measured photoinduced changes in optical transmission and found a resp...Molecular vibrations; Nile blue 690; Dyes1986
509 Boehme, ChristophObservation of precursor pair formation of recombining charge carriersAn experiment is presented which allows the observation of charge-carrier pair formation that precedes electronic transitions such as spin-dependent recombination or spin-dependent transport. It is based on an electrically detected magnetic-resonance-induced rotary echo sequence. The experimental de...Charge carriers2009-07
510 Rogachev, AndreyObservation of shot noise in phosphorescent organic light-emitting diodesWe employed a cross correlation method to study current noise in phosphorescent organic light-emitting diodes. The noise spectra revealed two frequency-dependent components. The first component displays 1/ f 1.3 dependence and correlates with the light emission of the devices. The second component i...2014-01-01
511 Sokolsky, PierreObservation of the reaction νµ + p →νµ + p+We have observed the elastic neutral - current reaction vµ +p→vµ +p and compared it to the quasielastic reaction vµ +n→µ +p. We have measured the ratio of the two reactions to be 0.23 ± 0.09.1976-07
512 Kieda, David B.Observation of the shadows of the moon and sun using 100 TeV cosmic raysThe Chicago Air Shower Array (CASA) is a large ground-based scintillation detector [1-4]. It is located at the Dugway Proving Ground is west central Utah, latitude 40°N and mean atmospheric depth 870 g / c m 2. A schematic aerial view of CASA is shown in Fig. 1. Each dot represents one scintil...Chicago Air Shower Array; Scintillation detectors; Ultrahigh energy cosmic rays1994-02
513 Sokolsky, PierreObservation of the suppression of the flux of cosmic rays above 4×10^19eVThe energy spectrum of cosmic rays above 2.5 x 10^18 eV, derived from 20 000 events recorded at the Pierre Auger Observatory, is described. The spectral index γ of the particle flux, J∞ E-γ, at energies between 4 x 10^18 eV and 4 x 10^19 eV is 2.69 ± 0.02(stat) ± 0.06(syst), steepening to 4.2 ...Extensive air showers; Energy spectrum; Fluorescence; Suppression2008-08
514 Ailion, David CharlesObservation of ultraslow translational diffusion in metallic lithium by magnetic resonanceThe theory of a new magnetic-resonance technique for studying the ultra slow motion of atoms was presented in a previous paper. In this paper, we present its experimental confirmation for the case of translational diffusion in lithium metal. By this technique the mean time between atomic jumps r can...Ultraslow atomic motion; Magnetic resonance1965
515 Sokolsky, PierreObserving the ultrahigh energy universe with OWL eyesThe goal of the Orbiting Wide-field Light-collectors (OWL) mission is to study the origin and physics of the highest energy particles known in nature, the ultrahigh energy cosmic rays (UHECRs). The OWL mission consists of telescopes with UV sensitive cameras on two satellites operating in tandem to ...Ultra-high energy cosmic rays; Fluorescence; Air showers2004-11
516 Mattis, Daniel C.Odd-spin-cluster interactionsWe consider interactions of Ising spins three at a time, five at a time, etc., as distinguished from the conventional interactions (two at a time). To illustrate, we calculate the exact thermodynamics of three-spin-cluster interactions in one dimension with and without a magnetic field. We find regu...Ising spins; Binary clusters1983-03
517 Wu, Yong-ShiOn gauge invariance of noncommutative Chern-Simons theoriesMotivated by possible applications to condensed matter systems, in this paper we construct U(N) noncommutative Chern-Simons (NCCS) action for a disc and for a double-layer geometry, respectively. In both cases, gauge invariance severely constrains the form of the NCCS action. In the first case, it ...2002-05
518 Gondolo, PaoloOn the direct detection of extragalactic weakly interacting massive particlesWe consider the direct detection of weakly interacting massive particles (WIMPs) reaching the Earth from outside the Milky Way. If these WIMPs form a distinct population they will, although of much lower flux than typical galactic halo WIMPs, have a number of features which might aid in their ulti...Extragalactic WIMPs; Weakly interacting massive particles2001-10
519 Wu, Yong-ShiOn the Kadomtsev-Petviashvili hierarchy, Ŵ∞ algebra, and conformal SL(2,R)/U(1) model. II. The quantum caseThis article is devoted to constructing a quantum version of the famous Kadomtsev-Petviashvili (KP) hierarchy by deforming its second Hamiltonian structure, namely, the nonlinear W, algebra. This is achieved bx quantizing the conformal noncompact SL(2,R) k/ U(1) coset model, in which W, appears as ...Kadomtsev-Petviashvili hierarchy; Quantum charges; W-algebras1993
520 Lupton, John MarkOn-chain defect emission in electroluminescent polyfluorenesWe present time-resolved photoluminescence measurements on a range of poly- and oligofluorenes with different molecular weights in both dilute solution and thin films. The commonly observed parasitic broad green emission band, which has previously been attributed to an excimer, is identified in all...Defect emission; Parasitic broad green emission band2002
521 Lupton, John MarkOne and two-photon photocurrents from tunable organic microcavity photodiodesWe have constructed multilayer thin-film organic microcavity photodiodes with the photoactive layer comprised of a spin-coated conjugated polymer and an evaporated C60 layer. The electrodes are designed as semitransparent mirrors which form a resonant cavity structure. The photocurrent spectra show ...Photocurrents; Microcavity photodiodes; Tunable photodiodes2003
522 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
523 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
524 Mattis, Daniel C.Operator identity and applications to models of interacting electronsBy correct reduction of some quartic forms in fermion field operators, I eliminate all but a constant and some quadratic terms. I can use this to transform the Wolff model, of a magnetic impurity in a nonmagnetic metal, into a solvable quadratic form in fermions. Applying the same method (with less ...Fermi operators1976-03
525 Vardeny, Zeev ValentineOptical absorption in the substituted phenylene-based conjugated polymers: theory and experimentWe investigate theoretically and experimentally the effects of (2,5) chemical substitution on the optical absorption in the phenylene-based conjugated polymers. Theoretically, substitution destroys both the charge-conjugation symmetry and spatial symmetry that characterize the unsubstituted materia...Phenylene-based conjugated polymers; Optical absorption; Chemical substitution; Coulomb correlated models1997-01
501 - 525 of 924