UScholar Works
 
Filters: Department: "Physics" Collection: "ir_uspace"
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CreatorTitleDescriptionSubjectDate
1 Symko, Orest GeorgeAcoustic approach to thermal management: miniature thermoacoustic enginesAn acoustic approach to thermal management in electronics can be efficient and it can be directly interfaced with electronic devices. It is based on two types of thermoacoustic heat engines, which are being developed for microcircuit applications. One type of device, the prime mover, converts heat t...Thermoacoustic engines; Thermal management2006
2 Vardeny, Zeev Valentine; Nahata, AjayAnomalous transmission through heavily doped conducting polymer films with periodic subwavelength hole arrayWe observed resonantly enhanced (or anomalous transmission) terahertz transmission through two-dimensional (2D) periodic arrays of subwavelength apertures with various periodicities fabricated on metallic organic conducting polymer films of polypyrrole heavily doped with PF6 molecules [PPy(PF6)]. Th...2006
3 Dawson, KyleCCD testing and characterization for dark energy surveyA description of the plans and infrastructure developed for CCD testing and characterization for the DES focal plane detectors is presented. Examples of the results obtained are shown and discussed in the context of the device requirements for the survey instrument.DES2006
4 Vardeny, Zeev ValentineComment on "Large optical nonlinearity of semiconducting single-walled carbon nanotubes under resonant excitations"In a recent Letter Maeda et al. studied the optical nonlinearities of single-walled carbon nanotubes (SWNT) films using both ??Z-scan?? and ??pump and probe?? (PP) techniques with ~100 fs time resolution [1]. They found that SWNTs have a large resonant third-order nonlinear optical susceptibili...SWNT; Coherent artifact2006
5 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
6 Wu, Yong-ShiDynamics of giant-gravitons in the LLM geometry and the fractional quantum Hall effectThe LLM's 1/2 BPS solutions of IIB supergravity are known to be closely related to the integer quantum Hall droplets with filling factor v = 1, and the giant gravitons in the LLM geometry behave like the quasi-holes in those droplets. In this paper we consider how the fractional quantum Hall effect ...2006
7 Bromley, Benjamin C.Eigenspectral computtations for linear gravity and nonlinear toy modelsThe periodic standing-wave approach to binary inspiral assumes rigid rotation of gravitational fields and hence helically symmetric solutions. To exploit the symmetry, numerical computations must solve for "helical scalars," fields that are functions only of corotating coordinates, the labels on the...Binary black holes; General relativity; Standing wave2006
8 Dawson, KyleHigh-voltage-compatible fully depleted CCDsWe describe charge-coupled device (CCD) development activities at the Lawrence Berkeley National Laboratory (LBNL). Back-illuminated CCDs fabricated on 200-300 fxm thick, fully depleted, high-resistivity silicon substrates are produced in partnership with a commercial CCD foundry. The CCDs are full...Large Synoptic Survey Telescope; X-ray emission; XMM22352006
9 Gondolo, PaoloPhysics of the very early universe: what can we learn from cosmological observations?Cosmological observations are starting to probe the evolution of the Universe before nucleosynthesis. The observed fluctuations in the cosmic microwave background and in the distribution of matter can be traced back to their origin during inflation, and the inflaton potential has begun to be unrave...Neutralinos; Inflatons; Moduli fields2006
10 Vardeny, Zeev Valentine; Nahata, AjayResonantly-enhanced transmission through a periodic array of subwavelength apertures in heavily-doped conducting polymer filmsWe observed resonantly-enhanced terahertz transmission through two-dimensional (2D) periodic arrays of subwavelength apertures with various periodicities fabricated on metallic organic conducting polymer films of polypyrrole heavily doped with PF6 molecules [PPy(PF6)]. The"anomalous transmission" s...Resonantly enhanced transmission; Subwavelength apertures; Polypyrrole; PPy(PF6)2006
11 Williams, Clayton C.Single electron tunneling force spectroscopy of an individual electronic state in a non-conducting surfaceA tunneling spectroscopy technique to measure the energy level of an electronic state in a completely nonconducting surface is demonstrated. Spectroscopy is performed by electrostatic force detection of single-electron tunneling between a scanning probe and the state as a function of an applied vo...Tunneling; Spectroscopy; Single electron; Scanning tunneling microscope2006
12 Lupton, John MarkStimulated emission depletion of triplet excitons in a phosphorescent organic laserTriplet formation is investigated in an optically pumped polymer laser by detecting the phosphorescence emission after excitation. A clear correlation is observed between the onset of lasing and a saturation of phosphorescence intensity due to stimulated emission depletion of the singlet state and t...Triplet excitons; Triplet formation; Emission depletion; Phosphorescent organic laser; Optically pumped polymer laser2006
13 Gerton, JordanTip-enhanced fluorescence microscopy of high-density samplesHigh-density samples of fluorescent quantum dots (QDs) were imaged using an apertureless near-field optical microscopy technique. QD fluorescence was modulated by oscillating a silicon atomic force microscope tip above an illuminated sample and a lock-in amplifier was used to suppress background fr...2006
14 Vardeny, Zeev ValentineUniversal properties of quasi-one-dimensional excitons in semiconducting single-walled carbon nanotubes and ∏-conjugated polymersThe nature of the primary photoexcitations in semiconducting single-walled carbon nanotubes (S-SWCNTs) is of strong current interest. We have studied the emission spectra of S-SWCNTs and two different rr-conjugated polymers in solutions and films, and have also performed ultrafast pump-probe spectr...Carbon nanotubes; pi-conjugated polymers; SWCNT; Photoexcitation; Optoelectronic properties; Quasi-one-dimensional2006
15 Wu, Yong-ShiAlgebraic solution for a two-level atom in radiation fields and the Freeman resonancesUsing techniques of complex analysis in an algebraic approach, we solve the wave equation for a two-level atom interacting with a monochromatic light field exactly. A closed-form expression for the quasienergies is obtained, which shows that the Bloch-Siegert shift is always finite, regardless of ...Bloch-Siegert shift; Freeman resonances; Quasienergies2006-02
16 Gondolo, PaoloAnnual modulation of dark matter in the presence of streamsIn addition to a smooth component of weakly interacting massive particle (WIMP) dark matter in galaxies, there may be streams of material; the effects of WIMP streams on direct detection experiments is examined in this paper. The contribution to the count rate due to the stream cuts off at some char...WIMP streams; Weakly interacting massive particles; Cutoff energy; Halo models; Sagittarius dwarf galaxy; Recoil energy; Sgr stream2006-08
17 Wu, Yong-ShiBraid group, gauge invariance, and topological orderTopological order in two-dimensional systems is studied by combining the braid group formalism with a gauge invariance analysis. We show that flux insertions (or large gauge transformations) pertinent to the toroidal topology induce automorphisms of the braid group, giving rise to a unified algebrai...Braid group; Topological order; Zero temperature; Two-dimensional systems2006-07
18 Sokolsky, PierreComparison of air fluorescence and ionization measurements of E.M. shower depth profiles: test of a UHECR detector techniqueMeasurements are reported on the fluorescence of air as a function of depth in electromagnetic showers initiated by bunches of 28.5 GeV electrons. The light yield is compared with the expected and observed depth profiles of ionization in the showers. It validates the use of atmospheric fluorescence...Air fluorescence; Electromagnetic shower; Ultra-high energy cosmic rays; Ionization2006-02
19 Gondolo, PaoloEffect of a late decaying scalar on the neutralino relic densityIf the energy density of the Universe before nucleosynthesis is dominated by a scalar field Ø that decays and reheats the plasma to a temperature TRH smaller than the standard neutralino freeze-out temperature, the neutralino relic density differs from its standard value. In this case, the relic de...Neutralinos; Relic density; Reheating temperature2006-10
20 Mishchenko, Eugene; Raikh, Mikhail E.Electrostatics of straight and bent single-walled carbon nanotubesResponse of a single-walled carbon nanotube to external electric field, F, is calculated analytically within the classical electrostatics. Field-induced charge density distribution is approximately linear along the axis of a metallic nanotube and depends rather weakly, as ln(h/ r), on the nanotube...Electrostatics2006-10
21 Lupton, John MarkEvidence for temperature-independent triplet diffusion in a ladder-type conjugated polymerWe study the temperature dependence of triplet formation and decay by considering the phosphorescence dynamics in a prototypical conjugated polymer matrix. The dynamics of triplet formation as a function of temperature are unraveled by applying an electric field during optical singlet generation a...Triplet diffusion; Triplet excitons; Ladder-type conjugated polymers; Temperature dependence2006-12
22 Gerton, JordanFluorescence near-field microscopy of DNA at Sub-10A nm resolutionWe demonstrate apertureless near-field microscopy of single molecules at sub-10 nm resolution. With a novel phase filter, near-field images of single organic fluorophores were obtained with ~sixfold improvement in the signal-to-noise ratio. The improvement allowed pairs of molecules separated by ~...2006-12
23 Mishchenko, EugeneGapless surfaces in anisotropic superfluidsWe demonstrate when p-wave pairing occurs between species whose free Fermi surfaces are mismatched the gap generally vanishes over a two-dimensional surface. We present detailed calculations of condensation energy, superfluid density (Meissner mass) and specific heat for such states. We also consi...Anisotropic superfluids; Meissner mass2006-11
24 Wu, Yong-ShiGeneral theorem relating the bulk topological number to edge states in two-dimensional insulatorsWe prove a general theorem on the relation between the bulk topological quantum number and the edge states in two-dimensional insulators. It is shown that whenever there is a topological order in bulk, characterized by a nonvanishing Chern number, even if it is defined for a nonconserved quantity s...Edge states; Bulk topology; Chern number2006-07
25 Mishchenko, EugeneGeneration of spin current by Coulomb dragCoulomb drag between two quantum wires is exponentially sensitive to the mismatch of their electronic densities. The application of a magnetic field can compensate this mismatch for electrons of opposite spin directions in different wires. The resulting enhanced momentum transfer leads to the conv...Spin current; Coulomb drag; Quantum wires2006-12
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