UScholar Works
 
Filters: Department: "Physics" Collection: "ir_uspace"
451 - 475 of 924
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CreatorTitleDescriptionSubjectDate
451 DeTar, CarletonMultiperipheral dynamics at general momentum transferWe extend the group-theoretical analysis of the multiperipheral integral equation of Chew, Goldberger, and Low to general momentum transfers. Using a set of variables for the multiparticle phase space analogous to those of Bali, Chew, and Pignotti, we obtain, through the 0(2,1) symmetry, a partial...Multiperipheral model1969-12
452 Vardeny, Zeev ValentineMultiple resonances in microdisk lasers of ∏-conjugated polymersWe have fabricated microdisk lasers from p-conjugated polymers that show multiline emission spectrum upon optical excitation. Using Fourier transform analysis, each emission line is assigned integer to an interger Bessel function that helps to estimate the field distribution inside the photoexcited ...Multiple resonances; Microdisks; Microdisk lasers; pi-conjugated polymers2002
453 Wu, Yong-ShiMultisheet configuration space and fractional quantum statisticsWe show that if one uses a multisheet configuration space for a system of identical particles, then fractional quantum statistics in two dimensions can be geometrically characterized as a topological quantum number for going from one sheet to the next. Furthermore, the spectrum of such a g-sheet s...1992-05
454 Dawson, KyleMultiwavelength observations of a rich galaxy cluster at z ~ 1: the HST/ACS colour-magnitude diagramXMMU J1229+0151 is a rich galaxy cluster with redshift z = 0.975 that was serendipitously detected in X-rays within the scope of the XMM-Newton Distant Cluster Project. Both HST/ACS observations in the i775 and z850 passbands and VLT/FORS2 spectroscopy were obtained, in addition to follow-up Near-In...Passive galaxies; Redshift2009-07
455 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
456 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
457 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
458 Gerton, JordanNanoscale fluorescence imaging using a single-wall carbon nanotubeA single-wall carbon nanotube attached to an AFM probe is used for near-field optical imaging of 20 nm diameter fluorescent spheres and 5 nm diameter CdSe quantum dots.2007-05
459 Gerton, JordanNanoscale fluorescence microscopy using carbon nanotubesWe demonstrate the use of single-walled carbon nanotubes as nano-optical probes in apertureless near-field fluorescence microscopy. The carbon nanotubes strongly quench fluorescence leading to near-field contrast with spatial resolution of ~20 nm.2008-07
460 Gerton, JordanNanoscale fluorescence microscopy using carbon nanotubesWe demonstrate the first reported use of single-walled carbon nanotubes as nano-optical probes in apertureless nearfield fluorescence microscopy. We show that, in contrast to silicon probes, carbon nanotubes always cause strong fluorescence quenching when used to image dye-doped polystyrene spheres...2008
461 Wu, Yong-ShiNanoscale magnetic-domain structure in colossal magnetoresistance islandsMagnetic force microscopy reveals the nature of local magnetic structure in submicron islands of colossal magnetoresistance (CMR) thin films. The evolution of domains in a magnetic field reveals the importance of shape anisotropy as well as magnetostriction in determining the micromagnetics in suc...Magnetic domain; Colossal magnetoresistance islands2001-11
462 Ailion, David CharlesNature of Ag+ self-diffusion in AgFMeasurements of the nuclear magnetic resonance (NMR) dipolar relaxation times T w and T i (51°) have been made on the 1 9 F resonance in AgF powder over the temperature range 60-300 K. Also the technique of Stokes and Ailion for detecting the diffusion of weakly magnetic spins has been verified f...NMR; Nuclear magnetic resonance; Diffusion; Ionic conductivity1981
463 Ailion, David CharlesNature of the incommensurate-paraelectric transition: a two dimensional exchange-difference NMR study87Rb two-dimensional exchange-difference NMR was used to study collective motions in the incommensurate (I) and paraelectric (P) phases of Rb2ZnCl4, which elucidate the nature of the I-P transition. We measured the cross-peak frequency displacement vs mixing time and observed a gradual increase towa...Incommensurate systems; NMR; Paraelectric phase2000
464 DeTar, CarletonNature of the thermal phase transition with Wilson quarksWe describe a series of simulations of high temperature QCD with two flavors of Wilson quarks aimed at clarifying the nature of the high temperature phase found in current simulations. Most of our work is with four time slices, although we include some runs with six and eight time slices for compar...Wilson quarks; Landau gauge; Polyakov loop; Phase transitions1994-04
465 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
466 Vardeny, Zeev Valentine; Gellermann, WernerNear-infrared ps transient photoinduced absorption in conjugated systemsWe demonstrate the use of a color center laser in a pump-and-probe correlation technique which enables us to extend the probe spectral range into the infrared. As a result, we find strong photoinduced infrared absorption in several 7t-conjugated polymers and oligomers. We associate this absorption w...Ultrafast spectroscopy; Color center laser; Photoinduced absorption; Singlet excitons; Even parity states; Odd parity states; Infrared absorption1997
467 Gondolo, PaoloNeutralino dark matter vs galaxy formationNeutralino dark matter may be incompatible with current cold dark matter models with cuspy dark halos, because excessive synchrotron radiation may originate from neutralino annihilations close to the black hole at the galactic center.Neutralinos; Cuspy dark halos2000
468 Gondolo, PaoloNeutralino decay rates with explicit R-parity violationWe compute the neutralino decay rate in the minimal supersymmetric standard model with the addition of explicit R-parity violation. We include the complete squark and slepton mixing matrices, previously neglected, and we improve and correct published formulas. These decays are relevant to accelerat...Neutralinos; R-parity; Decay rates; Sfermions1998-03
469 Gondolo, PaoloNeutralino relic density including coannihilationsWe evaluate the relic density of the lightest neutralino, the lightest supersymmetric particle, in the minimal supersymmetric extension of the standard model. For the first time, we include all coannihilation processes between neutralinos and charginos for any neutralino mass and composition. We u...Neutralinos; Charginos; Higgsinos; Relic density; Coannihilations; Boltzmann equation1997-08
470 Gondolo, PaoloNeutralino with the right cold dark matter abundance in (almost) any supersymmetric modelWe consider nonstandard cosmological models in which the late decay of a scalar field Ø reheats the Universe to a low reheating temperature, between 5 MeV and the standard freeze-out temperature of neutralinos of mass mx. We point out that in these models all neutralinos with standard density Ώstd...Neutralinos; Reheating temperature2006-07
471 Gondolo, PaoloNeutralinos as dark matter in the minimal supergravity modelA new approach to the phenomenological study of the minimal supergravity model is presented in which the model is effectively parametrized in terms of five low energy observables. Radiative corrections due to large Yukawa couplings and particle-sparticle mass splitting are included into the analysis...Neutralinos1992
472 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
473 Ailion, David CharlesNew NMR techniques to study diffusion in multispin crystalsWe present a new NMR method for studying slow diffusion in multispin systems. With this method we can vary the effect of a particular spin species' motion relative to the others, thus enabling us to separate and identify the component motions. We present a new pulse sequence for measuring T1L', a ge...NMR; Nuclear magnetic resonance; Crystals; Nuclear-spin species; Diffusion; Molecular rotations1977
474 Ailion, David CharlesNew technique for determining the diffusion mechanism by NMR: application to Cl35 diffusion in TlClA major problem in the study of atomic motions is the determination of the dominant mechanism responsible for translational diffusion. Recently Ailion and Ho predicted that the rotating-frame spin-lattice relaxation time T l p would have an angular dependence which depends on the diffusion mechanis...Diffusion; Solids; NMR1972
475 Ailion, David CharlesNew two-point calibration method for platinum resistance thermometers for the range 75-400KIn this paper we describe a new method for calibrating high quality platinum resistance thermometers to ±0.01 "C over the temperature range 75-400 K. This method requires resistance measurements at only two temperatures (liquid nitrogen and the ice point) in contrast to other methods which require ...Platinum; Resistance thermometers; Physics instruments1969
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