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Characteristic Temperature (characteristic + temperature)

Distribution by Scientific Domains

Physics and Astronomy	80%

Selected Abstracts

Pressure Effect Investigations on the Spin Crossover Systems{Fe[H2B(pz)2]2(bipy)} and {Fe[H2B(pz)2]2(phen)}

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2006
Ana Galet
Abstract Pressure effect studies on the spin crossover behaviour of the mononuclear compounds {Fe[H2B(pz)2]2(bipy)}(1) and {Fe[H2B(pz)2]2(phen)}(2) have been performed in the range of 105 Pa,1.02 GPa at variable temperatures (100,310 K). Continuous spin transitions and displacement of its characteristic temperature has been observed for 1 with increasing pressure. Meanwhile the response of 2 under applied pressures is quite unexpected, and can only be understood in terms of a crystallographic phase transition or change in the bulk modulus of the compound. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Internal-loss-limited maximum operating temperature and characteristic temperature of quantum dot laser

LASER PHYSICS LETTERS, Issue 4 2007
L. Jiang
Abstract Carrier-density-dependent internal optical loss sets an upper limit for operating temperatures and considerably reduces the characteristic temperature of a quantum dot laser. Such internal loss also constrains the shallowest potential well depth and the smallest tolerable size of a quantum dot at which the lasing can be attained. At the maximum operating temperature or when any parameter of the structure is equal to its critical tolerable value, the characteristic temperature drops to zero. (© 2007 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Where is the radiation edge in magnetized black hole accretion discs?

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008
Kris Beckwith
ABSTRACT General relativistic (GR) magnetohydrodynamic (MHD) simulations of black hole accretion find significant magnetic stresses near and inside the innermost stable circular orbit (ISCO), suggesting that such flows could radiate in a manner noticeably different from the prediction of the standard model, which assumes that there are no stresses in that region. We provide estimates of how phenomenologically interesting parameters like the ,radiation edge', the innermost ring of the disc from which substantial thermal radiation escapes to infinity, may be altered by stresses near the ISCO. These estimates are based on data from a large number of three-dimensional GRMHD simulations combined with GR ray tracing. For slowly spinning black holes (a/M < 0.9), the radiation edge lies well inside where the standard model predicts, particularly when the system is viewed at high inclination. For more rapidly spinning black holes, the contrast is smaller. At fixed total luminosity, the characteristic temperature of the accretion flow increases between a factor of 1.2 and 2.4 over that predicted by the standard model, whilst at fixed mass accretion rate, there is a corresponding enhancement of the accretion luminosity which may be anywhere from tens of per cent to order unity. When all these considerations are combined, we find that, for fixed black hole mass, luminosity and inclination angle, our uncertainty in the characteristic temperature of the radiation reaching distant observers due to uncertainty in dissipation profile (around a factor of 3) is greater than the uncertainty due to a complete lack of knowledge of the black hole's spin (around a factor of 2) and furthermore that spin estimates based on the stress-free inner boundary condition provide an upper limit to a/M. [source]

Optically pumped ultraviolet lasing of BeMgZnSe based quantum well laser structures

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2006
Yuuki Niiyama
Abstract Ultraviolet lasing by optically pumping from BeMgZnSe quantum well laser structures on GaP(001) substrate was demonstrated using molecular beam epitaxy (MBE). The lasing wavelength was 373 nm at 13 K. The threshold power density at 13 K was 415 kW/cm2. In addition, the characteristic temperature from 13 to 90 K was 87 K. The lasing was confirmed up to 130 K. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]