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1 Vardeny, Zeev Valentine; Symko, Orest GeorgeFemtosecond dynamics of quasi-particles in YBa2Cu3O7-δ superconductor filmsWe have studied the transient electronic response of YBa2Cu307-δ epitaxialy grown H T c superconductor thin films in the femtosecond time domain, using transient photoinduced reflectivity (AR) with 60 fsec time resolution. For temperatures T>Tc only a bolometric signal was observed with ARrO. For ...Femtosecond dynamics; YBa2Cu3O7-8; Transient electronic response; Transient optical response1991-03
2 Ailion, David CharlesFloating of the modulation wave and phase pinning in incommensurate Rb2ZnBr4Nuclear-magnetic-resonance measurements in incommensurate Rb2ZnBr4 show the existence of regions where the modulation wave is floating. The floating regions coexist with other regions where the modulation wave is static. Impurity phase pinning and a roughening of the modulation wave at higher temper...Floating; Incommensurate phase; Phason mode; Lattices1983
3 Vardeny, Zeev ValentineAnomalous optical and ESR properties of doped polydiethynylsilanesThe optical, transport, and ESR properties of soluble conducting four-membered polydiethynylsilane heterocycles are described. The undoped one-dimensional gap is 2.0 eV in both films and solutions; no photoluminescence is observed. I2 doping induces a single absorption band at -1.05 eV in solutions...Polydiethynylsilane; Doped polydiethynylsilanes1991-09
4 DeTar, CarletonHadronic spectrum of the quark plasmaWe have carried out a numerical simulation in SU(3) lattice gauge theory with four flavors of low-mass staggered fermions at zero baryon-number density in the vicinity of the high-temperature phase transition on 6x 103 and 6x 102x20 lattices. Static screening masses (static susceptibilities) were m...Hadronic matter; Quark plasma; Chiral symmetry; Phase transitions1987-07
5 DeTar, CarletonScaling tests of the improved Kogut-Susskind quark actionImproved lattice actions for Kogut-Susskind quarks have been shown to improve rotational symmetry and flavor symmetry. In this work we find improved scaling behavior of the r and nucleon masses expressed in units of a length scale obtained from the static quark potential, and better behavior of the ...Instantons; Static potential2000-04
6 Vardeny, Zeev ValentineOptical bias control of dispersive relaxations in α-SI:HRelaxation of the photoinduced ir absorption band in a-Si:H was studied in the microsecond time domain as a function of cw bias illumination. The decays follow a power law t-a where the dispersion parameter a increases with bias illumination. At low temperatures, a increases linearly with the stead...Optical bias; Dispersive relaxations; Amorphous silicon; a-Si:H; Photoinduced absorption; Bias-controlled tunneling; Multiple trapping1984-01
7 DeTar, CarletonCritical behavior in Nt=4 staggered fermion thermodynamicsQuantum chromodynamics with two zero mass flavors is expected to exhibit a phase transition with O(4) critical behavior. Fixing the universality class is important for phenomenology and for facilitating the extrapolation of simulation data to physical quark mass values. Other groups have reported r...Staggered fermions; Phase transitions2000-01
8 Wu, Yong-ShiTime variation of Newton's gravitational constant in superstring theoriesThe present time variation of coupling constants in superstring theories with currently favorable internal backgrounds critically depends on the shape of the potential for the size of the internal space. If the potential is almost flat, as in perturbation theory to all orders, the value of G/G for N...Gravitational constant; Time variation1986-10
9 Vardeny, Zeev ValentineInfrared ultrafast optical probes of photoexcitations in ∏-conjugated organic semiconductorsWe measured the ultrafast dynamics of photoexcitations in a variety of semiconductor ∏-conjugated polymer films and solutions, in the spectral range from 0.13 eV to 1.05 eV and time domain from 100 fs to 800 ps. The measurements were made in the low signal regime, where the relative changes in tra...Infrared ultrafast optical probes; Photoexcitations; Ultrafast dynamics; MEH-PPV2005
10 Ailion, David CharlesNMR relaxation study of molecular motions between unequal potential wells in solid trans, trans- muconodinitrileWe report observations of extremely unusual proton NMR relaxation rates in solid trans, transmuconodinitrile (TMD, N=C-CH = CH-CH = CH-C = N). In particular we measured, over the temperature range 77-423 °K, proton dipolar relaxation times Tw and spin lattice relaxation times Tt (at 24 and 58 MH...NMR; Nuclear magnetic resonance; Lattices; Relaxation time1977
11 Sokolsky, PierreAn analog light scattering experiment of hexagonal icelike particles. part I: experimental apparatus and test measurementsAn experimental apparatus to measure the scattering properties of hexagonal icelike particles in the analog manner at the helium neon laser wavelength of 0.633 mm has been designed and built. The instrument consists of an array of 36 highly sensitive and linear photodiode detectors that are positi...1999
12 Bernstein, Paul S.; Gellermann, WernerMacular pigment Raman detector for clinical applicationsClinical studies of carotenoid macular pigments (MP) have been limited by the lack of noninvasive, objective instruments. We introduce a novel noninvasive optical instrument, an MP Raman detector, for assessment of the carotenoid status of the human retina in vivo. The instrument uses resonant excit...Diagnosis, Computer-Assisted; Equipment Failure Analysis; Sensitivity and Specificity2004
13 Vardeny, Zeev ValentineUltrafast femtosecond relaxation processes in luminescent and nonluminescent conducting polymersWe have employed the time-resolved photomodulation (PM) technique to study the photoexcitation dynamics in a luminescent (Si-PT) and nonluminescent ( s-(CH)x ) conducting polymers in the low signal limit. In each polymer, we identify two exponential decay processes in the PM decay, with characterist...Ultrafast femtosecond relaxation; Femtosecond spectroscopy; Pump-and-probe technique; PM decay; Polarization memory; Bi-exponential response1997
14 Vardeny, Zeev ValentinePhoto induced infrared active phonons in trans polyacetyleneWe measured photogenerated ir active phonons in trans-(CH) by the photoinduced absorption technique. A correlation was found to exist with a photoinduced absorption band in which electronic transitions are involved. Our results show photoproduction of free charged defects with long lifetimes.Photoinduced phonons; Trans polyacetylene1983-06
15 DeTar, CarletonB̄→D*ℓν̄ form factor at zero recoil from three-flavor lattice QCD: a model independent determination of [Vcb]We present the first lattice QCD calculation of the form factor for B→ D* lv with three flavors of sea quarks. We use an improved staggered action for the light valence and sea quarks (the MILC configurations), and the Fermilab action for the heavy quarks. The form factor is computed at zero recoi...Staggered quarks2009-01
16 Mishchenko, EugenePolarized electric current in semiclassical transport with spin-orbit interactionSemiclassical solutions of two-dimensional Schrödinger equation with spin-orbit interaction and smooth potential are considered. In the leading order, spin polarization is in-plane and follows the evolution of the electron momentum for a given subband. Out-of-plane spin polarization appears as a ...Spin-polarized current; Sharvin conductance; Spin-orbit coupling2006-10
17 Vardeny, Zeev Valentine; Ehrenfreund, Eitan A.Comment on "Yield of singlet excitons in organic light-emitting devices: a double modulation photoluminescence-detected magnetic resonance study"In a recent Letter [1] Lee et al. studied the spin 1/2 photoluminescence-detected magnetic resonance (PLDMR) of a soluble derivative of poly-phenylene vinylene [MEH-PPV] using a double modulation scheme, where both the laser excitation intensity and the microwave power were modulated at ?ex and ?...Singlet excitons; PLDMR; Poly-phenylene vinylene; MEH-PPV; Quenching; Spin dependent recombination; OLED2006
18 Mattis, Daniel C.Theory of ferromagnetism and the ordering of electronic energy levelsConsider a system of N electrons in one dimension subject to an arbitrary symmetric potential, V(xi,…,xN), and let E(S) be the lowest energy belonging to the total spin value S. We have proved the following theorem: E(S) 1962-01
19 Rogachev, AndreyEffect of morphology on the superconductor-insulator transition in one-dimensional nanowiresWe study the effect of morphology on the low-temperature behavior of superconducting nanowires which vary in length from 86 nm to 188 nm. A well-defined superconductor-insulator transition is observed only in the family of homogeneous wires, in which case the transition occurs when the normal resist...One-dimensional wires; Superconductor-insulator transition; Homogeneous wires; Inhomogeneous wires; Morphology; Low-temperature behavior2004-05
20 Vardeny, Zeev ValentineUltrafast studies of laser-action in poly-(p-pherylene vinylene) filmsThe recent demonstration of emission spectral narrowing in ∏-conjugated polymer has stirred widespread interest to the phenomenon of laser-action in these materials. It is now generally believed that spectral narrowing in superior polymer films is caused by amplified spontaneous emission (i.e. si...Ultrafast studies; Poly-(p-pherylene vinylene); PPV; Laser-action1999
21 Vardeny, Zeev ValentinePicosecond optical generation and detection of phonon waves in a-As2Te3Using the pump and probe technique we have observed oscillations of photoinduced transmission in thin films of a-As2Te3. The oscillations have periods of 70-240 ps, depending on sample thickness. We ascribe these to phonon propagation in the films. Thermal expansion and carrier deformation potenti...Picosecond optical generation; a-As2Te3; Pump and probe technique1984
22 Mishchenko, EugeneInfrared absorption and Raman scattering on coupled plasmon-phonon modes in superlatticesWe consider theoretically a superlattice formed by thin conducting layers separated spatially between insulating layers. The dispersion of two coupled phonon-plasmon modes of the system is analyzed by using Maxwell's equations, with the influence of retardation included. Both transmission for the fi...Infrared absorption; Raman scattering2006-04
23 Vardeny, Zeev Valentine; Gellermann, WernerTwo-photon absorption spectra of luminescent conducting polymers measured over a wide spectral rangeWe report the two-photon absorption (TPA) spectra of poly(2,5-dibutoxy-p-phenylene acetylene) (PPADBO), poly(2,5-dioctyloxy-p-phenylene vinylene) (PPV-DOO), and poly(3-hexylthiophene) (PAT6) in the spectral range extending from 576 nm to 846 nm. Using the Z-scan technique on the polymers in solutio...Two-photon absorption; Two-photon saturation; Luminescent polymers; Dispersion; Polymer solution; PPA-DBO1997
24 Williams, Clayton C.Scanning capacitance microscopy on a 25 nm scaleA near-field capacitance microscope has been demonstrated on a 25 nm scale. A resonant circuit provides the means for sensing the capacitance variations between a sub-lGO-nra tip and surface with a sensitivity of 1X 10 19 F in a I kHz bandwidth. Feedback control is used to scan the tip at constant g...Scanning capacitance microscopy1989
25 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
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