UScholar Works
 
Filters: Date: "1998" Department: "Physics" Collection: "ir_uspace"
1 - 25 of 11
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CreatorTitleDescriptionSubjectDate
1 Vardeny, Zeev Valentine; Gellermann, WernerAmplified resonant Raman scattering in conducting polymer thin filmsUsing picosecond pulsed laser excitation, we investigate the optical emission characteristics of poly(2,5-dioctyloxy-p-phenylenevinylene), (DOO-PPV), thin films at high excitation intensities (~1-90 MW/cm2). We observe the presence of amplified resonance Raman scattering in the emission spectra of c...Amplified resonant Raman scattering; High excitation intensities; pi-conjugated polymers1998
2 Vardeny, Zeev ValentineCylindrical micolasers and light emitting devices from conducting polymersSubstantially improved, photopumped polymer lasers are demonstrated using microrings and microdisks of various diameters D ranging from 5 to 200 mm. Various cavity-dependent laser modes were observed, which for D,10 mm were dominated by a single longitudinal mode with linewidth of less than 1 Å. Th...Cylindrical micolasers; OLED; Photopumped polymer lasers; Microrings; Microdisks; Microlasers1998
3 Vardeny, Zeev ValentineDouble-modulation electro-optic sampling for pump-and-probe ultrafast correlation measurementsWe describe a novel electro-optic double-modulation (DM) sampling technique for ultrafast transient spectroscopy, which is characterized by a superior signal-to-noise ratio compared to that of a regular single-modulation technique. DM is achieved by a combined effect of a radio-frequency modulation,...Double-modulation; Electro-optic sampling; Ultrafast transient spectroscopy; Pump; Probe1998
4 Gondolo, PaoloEvidence for "sterile neutrino" dark matter?I show that it may be possible to explain the present evidence for a gamma-ray emission from the galactic halo as due to halo WIMP annihilations. Not only the intensity and spatial pattern of the halo emission can be matched but also the relic density of the candidate WIMP can be in the cosmologica...Sterile neutrino; WIMP; Weakly interacting massive particles; Annihilations; Z boson; Higgs sector1998
5 Vardeny, Zeev Valentine; Taylor, P. CraigExcitation energy dependence of photoinduced absorption in intrinsic a-Si:HWe have studied subgap absorption of intrinsic a-Si:H induced by below- and above-gap photoexcitation. We find very similar photoinduced subgap absorption spectra when excited with 2.4 eV or 1.2 eV light. Both spectra exhibit a power-law dependence on laser intensity ?T ~ 1a, where a is 0.5 and 0.7...Intrinsic a-Si:H; Subgap absorption; Photoinduced absorption; Gap photoexcitation; Photomodulation; Electronic states1998
6 Sokolsky, PierreHighest-energy cosmic raysWhat in the cosmos can possibly be accelerating protons to 1020 electron volts and beyond? And how can they preserve such extreme energies while plowing through the cosmic microwave background on their way to us?Energy spectrum; GZK cutoff; Atmospheric fluorescence1998
7 Gerton, JordanPhase-contrast imaging of atomic superfluid state in degenerate gas of 6Li atomsThe recent experimental realizations of Bose-Einstein condensation in trapped ultracold atomic gases composed of bosonic alkali atoms has generated a broad interest in studying different properties of these degenerate atomic Bose systems. Although the degenerate atomic gas composed of fermionic atom...1998
8 Vardeny, Zeev ValentinePlastic microring lasers on fibers and wiresPhotopumped, pulsed, narrow line laser emission is demonstrated using cylindrical microcavities formed by p-conjugated polymer thin films wrapped around thin glass optical fibers and metal wires with various diameters D. A variety of cavity-dependent resonant laser mode structures were observed, whi...Microring lasers; pi-conjugated polymers; pi-conjugated polymer thin films; Microcavities1998
9 Saam, BrianProtection circuitry for high-power diode laser arraysA comprehensive protection scheme is presented for use with high-power (;500 W dc input! diode laser arrays. The circuitry requires no separate power, using instead the voltage from the laser's power supply. Overcurrent and overvoltage silicon controlled rectifier crowbars are the primary protection...Protection circuitry; High-power diode laser arrays1998
10 Williams, Clayton C.Two step dopant diffusion study performed in two dimensions by scanning capacitance microscopy and TSUPREM IVWe report the results of a two-step two- dimensional (2D) diffusion study by scanning capacitance microscopy (SCM) and 2D SUPREM IV process simulation. A quantitative 2D dopant profile of a gate-like structure is measured with the SCM on a cross-sectioned polished silicon wafer. The gate-like struct...Scanning capacitance microscopy; SCM; Doping1998
11 Mattis, Daniel C.Uses of quantum field theory in diffusion-limited reactionsThe techniques of quantum field theory on a lattice are used to examine the diffusion and reaction processes of particles in a solid, such as vacancies or interstitials, or chemical species of all kinds which move by discrete random hopping processes and react in a prescribed way when they are in pr...Recombination; Dynamics; Equation1998
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