UScholar Works
 
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CreatorTitleDescriptionSubjectDate
526 Vardeny, Zeev ValentineOptical and magneto-optical studies of two-dimensional metallodielectric photonic crystals on cobalt filmsWe studied the optical transmission and magneto-optical effect through a subwavelength hole array fabricated on a ferromagnetic cobalt (Co) thin film in comparison to a control unperforated Co film having the same thickness. We found that the perforated film sustains extraordinary transmission bands...Metallodielectric photonic crystals; Cobalt films2004
527 Vardeny, Zeev ValentineOptical and transport studies of single molecule tunnel junctions based on self-assembled monolayersWe have fabricated a variety of novel molecular tunnel junctions based on self-assembled-monolayers (SAM) of two-component solid-state mixtures of molecular wires (1,4 methane benzene-dithiol; Me-BDT with two thiol anchoring groups), and molecular insulator spacers (1-pentanethiol; PT with one thio...2005-09
528 Vardeny, Zeev ValentineOptical bias control of dispersive relaxations in α-Si:HRelaxation of the photoinduced ir absorption band in α-Si:H was studied in the microsecond time domain as a function of cw bias illumination. The decays follow a power law t-α where the dispersion parameter a increases with bias illumination. At low temperatures, a increases linearly with the st...Optical bias control; Dispersive relaxations; a-Si:H; Amorphous silicon1984-01
529 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
530 Mishchenko, EugeneOptical conductivity of a two-dimensional electron liquid with spin-orbit interactionThe interplay of electron-electron interactions and spin-orbit coupling leads to a new contribution to the homogeneous optical conductivity of the electron liquid. The latter is known to be insensitive to many-body effects for a conventional electron system with parabolic dispersion. The parabolic...Optical conductivity; Electron liquid; Spin-orbit coupling2006-08
531 Vardeny, Zeev ValentineOptical modulation spectroscopy of a-Si:H based multilayer structuresSteady state optical modulation spectrum of a-Si:H/a-SiNx:H multilayer structure, its temperature dependence and time decay have been studied. For multilayers with very thin sublayers the onset of the spectrum is more gradual and occurs at higher energy than the spectrum for unlayered a-Si:H, indic...Optical modulation spectroscopy; a-Si:H; Amorphous silicon; Dangling bonds1986
532 Vardeny, Zeev ValentineOptical picosecond studies of carrier thermalization in amorphous siliconThermalization of photogenerated hot carriers in a-Si, a-Si:H and a-Si:H:F was studied using the pump and probe method with subpicosecond resolution. The process is optically observable because the absorption cross-section of the hot carriers depends on their excess energy. It was found that the en...Carrier thermalization; Amorphous silicon; Frohlich interaction1981
533 Vardeny, Zeev ValentineOptical picosecond studies of hot carriers in amorphous semiconductorsThermalization of photogenerated carriers in a-Si, a-Si:H, a-As2Se3 and a-Se was studied by measuring the photoinduced absorption with subpicosecond resolution. The thermalization process can be described by Frohlich interaction with polar phonons in a-Si:H and a-As2Se3 but not in a-Si. Using photo...Photogenerated carriers; Thermalization1981-10
534 Vardeny, Zeev ValentineOptical probes of excited states in poly (p-phenylenevinylene)We have studied electronic excited states in films of poly(p-phenylenevinylene) using picosecond transient and cw photomodulation, photoluminescence, and their excitation spectra, as well as electroabsorption spectroscopy. We have determined all the important energy levels of singlet excitons with...Poly (p-phenylenevinylene); Photoexcitation1994-01
535 Vardeny, Zeev ValentineOptical probes of photoexcitations in fullerene thin films from femtoseconds to millisecondsWe have studied photoexcitations in various fiillerene thin films using transient photomodulation and photoluminescence from 100 fs to 50 ms and absorption-detected magnetic resonance (ADMR). We show that singlet Frenkel type excitons are the primary photoexcitations; their recombination kinetics in...Photoexcitations; Femtosecond; Transient photomodulation; Transient photoluminescence; Frenkel type excitons; Triplet excitons1995
536 Vardeny, Zeev ValentineOptical probes of pristine and C60-doped silicon-bridged PT polymer; a novel highly luminescent, low bandgap polymerSilicon bridged PT polymer (PTSi) is a new soluble polymer with a strong luminescence in the infrared band (0-0 transition at 1.6 eV). We have applied various spectroscopies such as absorption, electroabsorption (EA), photo induced absorption (PA), electromodulated PA (EPA), photoluminescence (PL) a...Silicon bridged PT polymer; Low bandgap pi-conjugated polymer; C60 doping; Electric field induced exciton dissociation1997
537 Vardeny, Zeev ValentineOptical probes of ∏-conjugated polymer blends with strong acceptor moleculesWe used a variety of optical probes to study the primary and long-lived photoexcitations in blends of polyphenylene-vinylene derivative poly(2-methoxy-5(2'-ethyl)hexoxy-phenylenevinylene) (MEH-PPV) with various concentrations of a strong electron-acceptor molecule 2,4,7-trinitro-9-fluorenone (TNF...pi-conjugated polymers; pi-conjugated polymer blends; Acceptor molecules; Optical probes; Photoexcitations; MEH-PPV; Electron acceptors; Organic solar cells2009-05
538 Williams, Clayton C.Optical ranging by wavelength multiplexed interferometryA new optical technique is described for measurement of absolute distance. The approach is based upon a wavelength multiplexed heterodyne interferometer with FM demodulation. By temporally multiplexing discrete wavelengths in a heterodyne interferometer, a complete elimination of interferometric ra...Optical ranging; Distance1986
539 Vardeny, Zeev Valentine; Efros, Alexei L.Optical studies of 2D and 3D metallo-dielectric photonic crystalsWe have fabricated and studied two-dimensional (2D) and three-dimensional (3D) metallo-dielectric photonic crystals (MDPC) in the visible/near ir spectral range using a variety of optical techniques. The 2D MDPC showed anomalous transmission due to surface plasmon polaritons in resonance with the ph...Metallo-dielectric photonic crystals; Organic light emitting diodes; Anomalous transmission; surface plasmon polaritons; Opal photonic crystals; Metal infiltrated opals; Optical reflectivity; Transmission spectra2005
540 Vardeny, Zeev ValentineOptical studies of excess carrier recombination in α-Si:H: evidence of dispersive diffusionRelaxation of photoinduced optical absorption following pulsed laser excitation was measured between 0.5 pis and 10 ms in doped and undoped a-Si:H as a function of temperature. The recombination was found to be bimolecular diffusion limited. The diffusion coefficient of the excess carriers is time ...Hydrogenated amorphous silicon; a-Si:H; Excess carrier recombination; Dispersive diffusion1980-05
541 Vardeny, Zeev ValentineOptical studies of metallodielectric photonic crystals: bismuth and gallium infiltrated opalsWe have fabricated three-dimensional metallodielectric photonic crystals that consist of bismuth and gallium metals infiltrated into porous synthetic opals that have 300 nm diam silica balls. The specular reflectivity was measured in a broad spectral range from 0.3 to 25 mm using a variety of light ...Metallodielectric photonic crystals; Bismuth infiltrated opals; Gallium infiltrated opals; Bragg; Porous synthetic opals2004
542 Vardeny, Zeev ValentineOptical studies of ordered and disordered α-sexithiophene filmsWe have studied α-sexithiophene (α-6T) films by photoinduced absorption (PA) and optically-detected magnetic resonance (ODMR). The PA of the disordered film is composed of two polaron PA bands and one bipolaron PA band, each with its own vibronic side bands. Measurements of an ordered film indicat...Optically detected magnetic resonance; Sexithiophene conjugated oligomer1997
543 Vardeny, Zeev ValentineOptical studies of spin coherence in organic semiconductorsSpin coherence in organic oligomer and polymer semiconductors is a crucial property in determining the performance of organic spin devices. Using the techniques of photo-induced absorption (PA) detected magnetic resonance (PADMR) and photoluminescence (PL) detected magnetic resonance (PLDMR), we ha...Spin coherence; Organic spin devices2005
544 Vardeny, Zeev ValentineOptical studies of the charge transfer complex in polytiophene/fullerene blends for organic photovoltaic applicationsWe studied the photophysics of regioregular polythiophene/C61 (RR-P3HT/PCBM) blend films utilized for organic photovoltaic applications using the femtosecond transient and steady-state photomodulation techniques with above-gap and below-gap pump excitations and electroabsorption spectroscopy. We pro...2010-08
545 Vardeny, Zeev ValentineOptical studies of triplet excitations in poly(p-phenylene vinylene)We have studied energy states in the triplet manifold in films of poly(p-phenylene vinylene) (PPV) using a multitude of optical spectroscopies including photoinduced absorption, photoluminescence, their optically detected magnetic resonances, as well as their photogeneration action spectra. We foun...Triplet excitations; PPV1999-10
546 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
547 Vardeny, Zeev Valentine; Ehrenfreund, Eitan A.Optically detected magnetic resonance study of recombination mechanisms in polythiopheneFrom detailed optically detected magnetic resonance measurements in polythiophene, we show that the g=2.003 signal is luminescence enhancing, and that the signal comes from a broad photoluminescence band peaking near 1.65 eV. This band is tentatively assigned to the radiative recombination of polaro...Recombination mechanisms1988
548 Saam, BrianOptically polarized 129Xe NMR investigation of carbon nanotubesWe demonstrate the utility of optically polarized 129Xe NMR in a convection cell for measuring the surface properties of materials. In particular, we show adsorption of xenon gas on oxidatively purified single- and multiwalled carbon nanotubes. The interaction between xenon and multiwalled nanotube...Carbon nanotubes; Multiwalled nanotubes; 129Xe NMR; Gas adsorption2008-12
549 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
550 Gerton, JordanOptimizing contrast of tip-enhanced fluorescence microscopy for imaging high-density samplesQuantum dots are imaged using tip-enhanced fluorescence microscopy. Optimization of the operation parameters leads to high-contrast images of high-density samples and a novel photon analysis improves contrast further.2007-05
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