Browsing School of Physics by Date of Publication
Now showing items 21-40 of 840
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Optical detection of electron-nuclear double resonance for an S=1 luminescent center in GaP:O
(1991)The origin of a triplet (S=1) optically detected magnetic-resonance (ODMR) spectrum observed in the luminescence of GaP:O has been the subject of recent controversy. Originally identified with the negative-charge state of ... -
Transient nonlinear optical behavior of fluorescein-doped boric acid glass
(1992)The nonlinear optical properties of fluorescein-doped boric acid glass films have been investigated with sub-nanosecond laser pulses. With the use of degenerate four-wave mixing, large third-order susceptibilities of X(3) ... -
Giant energy product in nanostructured two-phase magnets
(American Physical Society, 1993)Exchange hardening of nanostructured two-phase systems composed of an aligned hard phase and a soft phase with high magnetization is investigated using an approach which yields analytic nucleation fields from the micromagnetic ... -
All-optical synchronization and multiplication of the frequency of mode-locked signals
(IEEE, 1993)We report all-optical synchronized multiplication by rational fractions of the modulation frequency of optical signals in self-pulsing two-section semiconductor laser diodes. The effect is based on the overlap of harmonics ... -
The influence of QSO emission-line velocity shifts on estimates of the intergalactic background intensity
(1993)Observations of the inverse effect indicate that the observed number of QSOs cannot provide sufficient radiation to reionize the intergalactic medium. We reanalyze the data set of one such study and show that bias in the ... -
Magnetoresistance in nanostructured Co-Ag prepared by mechanical alloying
(IEEE, 1993)Fine cobalt and silver powders have been ball-milled to yield a granular solid of composition Co30Ag70 in the form of coarse powder. The material is an intimate mixture of grains of fcc Co in a silver matrix. The cobalt ... -
Steady-State Drainage of an Aqueous Foam
(American Physical Society, 1993)The process of wetting of a monodisperse foam by the continuous addition of liquid from the top has been investigated for a cylindrical column. The velocity of the interface between dry and wet foam was found to vary as ... -
The HST absorption line key project. IX. Emission line studies of PG 2251+113
(American Astronomical Society, 1994)We present Hubble Space Telescope (HST) and quasi-simultaneous ground-based observations of the z = 0.3252 QSO PG 2251113. We find a correlation between line widths and the critical density for de-excitation of the forbidden ... -
Theory of diffusivelight scattering from disordered materials
(International Society for Optical Engineering, 1994)It is suggested that the measurement of the angular distribution of light transmitted through a thick slab of diffusively scattering material may provide information about the nature of the local scattering events. Monte ... -
Engineering the exciton linewidth in II-VI quantum well structures
(SPIE, 1994)The excitonic transition in Il-VI quantum well materials has recently been used as the basis for optical modulators and also as the lasing transition at low temperatures. The central aspect in the use of the exciton ... -
New rigid backbone conjugated organic polymers with large fluorescence quantum yields
(1995)The effect on optical emission of the presence of carbon?carbon triple bond linkages in conjugated aromatic copolymers is studied and leads to fluorescence quantum yields of up to 50%, substantially higher than most ... -
Performance and preliminary calibration of the Hopkins ultraviolet telescope on the Astro-2 mission
(American Astronomical Society, 1995)An improved version of the Hopkins Ultraviolet Telescope (HUT) made its second flight on the Astro-2 mission aboard the Space Shuttle Endeavour from 1995 March 2--18. The longer mission duration and greatly improved pointing ... -
Electron localization in mixed-valence manganites
(American Physical Society, 1995)Mixed-valence manganites (A3+0.7B2+0.3)MnO3 exhibit a resistivity peak with giant negative magnetoresistance below the Curie point. Residual resistivity ranges from 5?10-8 to 8?103 m, but the electronic heat capacity when ... -
Phase-matched gratings for enhanced forward degenerate four-wave mixing
(1995)A phase-matched grating to enhance the second-order diffracted signals generated by forward degenerate four-wave mixing has been proposed and demonstrated for the first time to the authors' knowledge. Experiments have been ... -
Epitaxial lift-off of ZnSe based II-VI structures
(1995)The epitaxial lift-off technique is applied to II?VI based structures. Epilayers of 255 nm thickness containing quantum wells are lifted off their substrates and redeposited onto polyimide coated GaAs. The technique has ... -
Simultaneous observation of direct and Raman-scattered O VI lines in the symbiotic nova RR telescopii
(American Astronomical Society, 1995)The optical spectra of some symbiotic binaries show two lines in the red region of the spectrum that cannot be identified with any known allowed or forbidden transitions. A case has been made that these lines are Raman-scattered ... -
Spin-dependent photoconductivity in CVD- and MBE-grown silicon-on-sapphire
(1995)Spin-dependent photoconductivity is observed in (100) silicon films grown on sapphire by CVD and MBE. The CVD films are either in their as-grown state or have undergone single or double solid-phase epitaxial regrowth. For ... -
Quasi-two-dimensional exciton in ZnSe/ZnMgSSe single quantum well
(American Physical Society, 1995)We have studied the quasi-two-dimensional exciton in ZnSe/ZnxMg1 ? xSySe1 ? y (x=0.85, y=0.21) single quantum wells (SQWs) by photoluminescence and photoluminescence excitation spectroscopy. Self-consistent calculations ...