UScholar Works
 
Filters: Department: "Physics" Collection: "ir_uspace"
1 - 25 of 28
Number of results to display per page
CreatorTitleDescriptionSubjectDate
1 Vardeny, Zeev Valentine; Ehrenfreund, Eitan A.Amplitude and phase modes in trans-polyacetylene: resonant Raman scattering and induced infrared activityThe resonant Raman scattering (RRS) from the three Ag modes of trans-polyacetylene and the charged-induced ir modes are analyzed with use of the amplitude- and phase-mode theories. It is shown that the observed phonon frequencies and the relative intensities of all modes obtained at various laser ex...Induced infrared activity; Ag modes; Amplitude modes; Phase modes; Trans-polyacetylene1987-07
2 Gondolo, PaoloAGAPEROS: searching for microlensing in the LMC with the pixel method. I. Data treatment and pixel light curves productionRecent surveys monitoring millions of light curves of resolved stars in the LMC have discovered several microlensing events. Unresolved stars could however signi _x000C_cantly contribute to the microlensing rate towards the LMC. Monitoring pixels, as opposed to individual stars, should be able to ...Data analysis techniques; Halo; Galaxies; Gravitational lensing; Pixel method; Large Magellanic Cloud; LMC1999
3 Ailion, David Charles93Nb NMR in the imcommensurate and quasi-commensurate phases of barium sodium niobateNMR spectra have been measured for the quadrupole perturbed 1/2 -1/2 transition of 9 3Nb in barium sodium niobate (BSN) between 300 and 650 K. The spectra are inhomogeneously broadened in the incommensurate (/) phase between T7 = 580 K and r c = 540 K as well as in the quasicommensurate (QC) phase ...NMR; Spectra; Barium sodium niobate; Line shapes1994
4 Gondolo, PaoloAgapeZ1: a large amplification microlensing event or an odd variable star towards the inner bulge of M31AgapeZ1 is the brightest and the shortest duration microlensing candidate event found to date in the Agape experiment. It occurred only 4200 from the centre of M31 at RA = 0h42m41:47s and Dec = 41°16'39.1" (J2000). Our photometry shows that the half intensity duration of the event is 5.3 days and ...AgapeZ1; Galaxy; Halo; Cosmology; Gravitational lensing; M31; Pixel method1999
5 Ailion, David CharlesNMR spectra and relaxation in incommensurate systems in the presence of a devil's staircaseThe possibility of discriminating true incommensurate phases from long period commensurate phases via NMR lineshape and spin-lattice relaxation measurements is discussed. The theoretical results are compared with experimental data in Rb2ZnCl4, Rb2ZnBr4, and [N(CH3)4]2ZnCl4. Devil's staircase effects...Incommensurate phases; Commensurate phases; Phason gap; Spin-lattice relaxation1985
6 Ailion, David CharlesThermal fluctuations and NMR spectra of incommensurate insulatorsThe effects of thermal order-parameter fluctuations on the NMR line shape of incommensurate systems are evaluated within the mean-field Landau theory and the results are compared with the 8 7Rb and 3 9K 1/2 -1/2 NMR spectra of Rb2ZnCl4 and K2Se04 just below the paraelectric-incommensurate transition...NMR spectra; Thermal fluctuations; Line shapes; Incommensurate insulators1994
7 Boehme, ChristophTransport and recombination through weakly coupled localized spin pairs in semiconductors during coherent spin excitationSemianalytical predictions for the transients of spin-dependent transport and recombination rates through localized states in semiconductors during coherent electron-spin excitation are made for the case of weakly spin-coupled charge-carrier ensembles. The results show that the on-resonant Rabi freq...Larmor frequency; Larmor separations2006-12
8 Vardeny, Zeev ValentinePhonon anomalies in Cu halidesA great number of the observed phonon anomalies in the zinc-blende phase of Cu-halide crystals are explained by means of a dynamical model. It is assumed that a Cu ion populates four equivalent off-center sites or its ideal position. The off-center Cu+ population is temperature and pressure dependen...Phonon anomalies; Cu-halide crystals; Cuprous halides1979-03
9 Vardeny, Zeev ValentineDisorder-induced TA Raman lines in mixed Cu-halide crystalsThe Raman spectra of CuClxBr1=x and CuBrxI1=x solid solutions are shown to contain extremely intense disorder-induced first-order TA phonons. The intensity of these lines is a function of the concentration x, and is highest in CuCl0.6oBr0.40. The TA spectrum, well resolved at low temperature, fits...Cuprous halides; CuBr; CuCl; CuI; mixed Cu-halide crystals1979-03
10 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
11 Boehme, ChristophSpin-dependent recombination - an electronic readout mechanism for solid state quantum computersIt is shown that coherent spin motion of electron-hole pairs localized in band gap states of silicon can influence charge carrier recombination. Based on this effect, a readout concept for silicon based solid-state spin-quantum computers as proposed by Kane is suggested. The 31P quantum bit (qbit) i...Spin readout; qbit; Spin-dependent recombination2002-10
12 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
13 Ailion, David CharlesDynamics of the pinned modulation wave in incommensurate bis (4-chlorophenyl) sulfone (BCPS)We show that both the anomalously huge resonance-frequency dependence of the 3 5Cl nuclear quadrupole resonance (NQR) spin-lattice relaxation time in BCPS, reported here for the first time, and its anomalous temperature dependence can be explained by large-scale fluctuations of the pinned modulation...NQR; Spin-lattice; Relaxation-time; Pinned modulation wave2002
14 Ailion, David CharlesMolecular reorientations in the ordered phases of KCN and NaCN studied by NMRWe have measured 13C and 23Na NMR spin-lattice relaxation times as a function of temperature in KCN and NaCN in order to study the head-to-tail reorientations of the CN- molecules in the two low-temperature ordered phases. We have combined our data with those of dielectric-response and ionic-thermal...Spin; Interactions; Fluctuations1984
15 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
16 Ailion, David CharlesNuclear magnetic resonance in LiF: a single nuclear-dipolar-spin temperature in crystals with more than one spin speciesIn a crystal containing more than one species of nuclear spin in a large dc magnetic field, the secular dipolar interactions between all spins, unlike as well as like, form a single reservoir described by a single spin temperature. We demonstrated this concept with experiments on LiF. In particula...Spin species; Spin-lattice relaxation; NMR; Nuclear magnetic resonance1977
17 DeTar, CarletonTensor component of the two-nucleon interaction in the quark-bag modelA previously developed method for computing the interaction energy of the two-nucleon system at short distances in the static MIT bag model of confined quarks is extended to all isospin and spin channels available to the two-nucleon interaction. The present study is restricted to spherical geometri...Bag models; Quark bag; Nucleons; Deformation energy1979-03
18 Ailion, David CharlesNMR lineshapes and order parameter determination in proton pseudo-spin glassesThe quadrupole-perturbed NMR line shape has been evaluated in the local approximation for an arbitrary static random-field distribution coexisting with Gaussian time-fluctuating random fields. The special case of a spin-glass-type static local random-field distribution is treated also. The results ...NMR; Nuclear magnetic resonance; Line shape; Random fields; Proton pseudo-spin-glasses1988
19 Mattis, Daniel C.Theory of the anomalous skin effect in normal and superconducting metalsChambers' expression for the current density in a normal metal in which the electric field varies over a mean free path is derived from a quantum approach in which use is made of the density matrix in the presence of scattering centers but in the absence of the field. An approximate expression use...Skin effect1958-07
20 Boehme, ChristophUltra-sensitive electrical detection of spin Rabi oscillation at paramagnetic defectsA short review of the pulsed electrically detected magnetic resonance (pEDMR) experiment is presented. PEDMR allows the highly sensitive observation of coherent electron spin motion of charge carriers and defects in semiconductors by means of transient current measurements. The theoretical foundatio...Rabi oscillations; Electron spin resonance; Paramagnetic defects2006-04
21 Saam, Brian3He spin exchange cells for magnetic resonance imagingWe present a protocol for the consistent fabrication of glass cells to provide hyperpolarized (HP) 3He for pulmonary magnetic resonance imaging. The method for producing HP 3He is spin-exchange optical pumping. The valved cells must hold of order 1 atm.L of gas at up to 15 atm pressure. Because char...3He; Spin exchange cells; Hyperpolarized 3He; Pulmonary magnetic resonance imaging; Spin-exchange optical pumping; SEOP; Glass cells2002
22 Boehme, ChristophTheory of the time-domain measurement of spin-dependent recombination with pulsed electrically detected magnetic resonanceThe theoretical foundations of the time domain measurement of spin-dependent charge carrier recombination by means of pulsed electrically detected magnetic resonance (EDMR) are outlined. Pulsed EDMR is based on the transient measurement of electrical currents in semiconductors after a coherent manip...Spin-dependent recombination2003-12
23 Kieda, David B.Toward a revival of stellar intensity interferometryBuilding on technological developments over the last 35 years, intensity interferometry now appears a feasible option by which to achieve diffraction-limited imaging over a square-kilometer synthetic aperture. Upcoming Atmospheric Cherenkov Telescope projects will consist of up to 100 telescopes, ...Intensity interferometry; Air Cherenkov Telescope2008
24 Ailion, David CharlesNMR methods for identifying and studying diffusion of different spin species in heteronuclear systemsWe introduce a new dipolar relaxation lime TU)' which characterizes the spin-lattice relaxation of secular dipolar interactions in the presence of a large rf field. Measurements of T]D' are particularly useful for studying slow atomic motions in muitispin systems, since such measurements enable us ...NMR; Nuclear magnetic resonance; Nuclear-spin species; Diffusion; Molecular rotations1978
25 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
1 - 25 of 28