UScholar Works
 
Filters: Journal Title: "Physical Review B" Collection: "ir_uspace"
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1 Vardeny, Zeev Valentine; Ehrenfreund, Eitan A.Apparent vibrational side bands in rr-conjugated systems: the case of distyrylbenzeneThe photoluminescence sPLd spectra of dilute solution and single crystals of distyrylbenzene show unique temperature-dependent vibronic structures. The characteristic single frequency progression at high temperatures is modulated by a low-frequency progression series at low temperatures. None of th...pi-conjugated systems; Distyrylbenzene; Vibrational side-bands; Vibronic structures; DSB2005-02
2 Liu, FengBending of nanoscale ultrathin substrates by growth of strained thin films and islandsMechanical bending is ubiquitous in heteroepitaxial growth of thin films where the strained growing film applies effectively an "external" stress to bend the substrate. Conventionally, when the deposited film is much thinner than the substrate, the bending increases linearly with increasing film th...Nanoscale ultrathin substrates; Strained thin films; Islands; Heteroepitaxial growth; Si substrate; Ge film2005-08
3 Vardeny, Zeev ValentineExciton dynamics in single-walled nanotubes: transient photoinduced dichroism and polarized emissionUltrafast relaxation of photoexcitations in semiconducting single-walled carbon nanotubes (S-NTs) were investigated using polarized pump-probe photomodulation (with 150 fs time resolution) and cw polarized photoluminescence (PL). Both annealed and unannealed thin NT films and D2O solutions of isola...Exciton dynamics; Single-walled carbon nanotubes; SWNT; Transient photoinduced dichroism; Polarized emission; Ultrafast relaxation; Photoexcitations2005-03
4 Liu, FengFirst-principles study of strain stabilization of Ge(105) facet on Si(001)Using the first-principles total energy method, we calculate surface energies, surface stresses, and their strain dependence of the Ge-covered Si (001) and (105) surfaces. The surface energy of the Si(105) surface is shown to be higher than that of Si(001), but it can be reduced by the Ge deposition...First-principles calculation; Strain stabilization; Ge(105); Si(001); Strained thin films; Epitaxial growth2005-09
5 Lupton, John MarkMonitoring surface charge migration in the spectral dynamics of single CdSe∕CdS nanodot/nanorod heterostructuresSpherical CdSe nanocrystals capped by a CdS rod-like shell exhibit interesting spectral dynamics on the single particle level. Spectral boxcar averaging reveals a high degree of correlation between the emission energy, spectral linewidth, phonon coupling strength, and emission intensity of the singl...Surface charge migration; Spectral dynamics; CdSe; CdS; Nanodot; Nanorod2005-11
6 Vardeny, Zeev ValentineOrganic random lasers in the weak-scattering regimeWe used the ensemble-averaged power Fourier transform (PFT) of random laser emission spectra over the illuminated area to study random lasers with coherent feedback in four different disordered organic gain media in the weak scattering regime, where the light mean free path, ℓ* is much larger tha...Organic random lasers; Gain media; pi-conjugated polymers; Opal photonic crystal; RG6; Optical gain; Chicken breast2005-01
7 Liu, FengSelf-organization of semiconductor nanocrystals by selective surface facetingThe formation and ordering of Si nanocrystals in dewetting and agglomeration of the thin single crystalline Si layer in silicon-on-insulator has been investigated using low-energy electron microscopy. The evolution of the Si dewetting and agglomeration is captured in real time, revealing the detai...Self-organization; Surface faceting; Silicon nanocrystals; Dewetting2005-12
8 Vardeny, Zeev Valentine; Efros, Alexei L.Theoretical and experimental studies of metal-infiltrated opalsThe optical properties of metal-infiltrated synthetic opals have been studied analytically, numerically, and experimentally in the visible and infrared spectral ranges. A simple model of weakly interacting resonant cavities is proposed to qualitatively understand the dispersion of electromagnetic ...Metal infiltrated opals; Metallic photonic crystals2005-04
9 Mattis, Daniel C.Theory of ferromagnetism in carbon foamAn explanation is proposed for spontaneous magnetism in the material, "carbon nanofoam," in terms of random ferrimagnetism. Wherever a carbon nanotube branches out, an electron trap is created at the junction. Electrons occupying neighboring junctions align their spins antiparallel.Carbon foam; Nanotubes; Nanofoam2005-04
10 Lupton, John MarkUltrafast dynamics of charge carrier photogeneration and geminate recombination in conjugated polymer: fullerene solar cellsWe investigate the nature of ultrafast exciton dissociation and carrier generation in acceptor-doped conjugated polymers. Using a combination of two-pulse femtosecond spectroscopy with photocurrent detection, we compare the exciton dissociation and geminate charge recombination dynamics in blends ...Ultrafast dynamics; Charge carrier photogeneration; Geminate recombination; Exciton dissociation; Acceptor-doped; MeLPPP; MDMO-PPV2005-11
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