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981.
Photoacoustic spectroscopy is employed to determine the luminescence quantum efficiency of Mn2+ in ZnS. Three spectra, photoacoustic spectrum, luminescence excitation spectrum and absorption spectrum, are compared. It is observed that the photoacoustic spectrum and the excitation spectrum behave complementarily. Radiative quantum efficiencies of the five excited states for Mn2+ have been determined. 相似文献
982.
Electrical resistivity and thermal expansion measurements were made to elucidate the structural relaxation of Ni78Si8B14 metallic glass, especially, the topological short range ordering. The decrease of the resistivity and the increase of its temperature coefficient were observed, and these changes due to the structural relaxation were discussed on the basis of the extended Ziman theory for metallic glasses proposed by Nagel. The densification of about 0.25% and the decrease of 4% in the thermal expansion coefficient were observed in the considerably relaxed sample. The topological short range ordering in Ni78Si8B14 metallic glass occurs rapidly at the annealing temperature above 200°C. 相似文献
983.
Hanaizumi Osamu Saito Makoto Ohtera Yasuo Kawakami Shojiro Yano Satoshi Segawa Yusaburo Kuramochi Eiichi Tamamura Toshiaki Oku Satoshi Ozawa Akira 《Optical and Quantum Electronics》2002,34(1-3):71-77
SiO2/air three-dimensional (3D) periodic structures were fabricated by removing Si layers partially from Si/SiO2 3D photonic crystals (PhCs) formed by using autocloning. CdS/SiO2 3D periodic structures were formed by introducing CdS into the SiO2/air structures by the TEA method and photoluminescence (PL) was observed from the introduced CdS. TiO2/air/CdS two-dimensional (2D) PhCs were also fabricated by introducing CdS into the voids of TiO2/air 2D periodic structures, in which SiO2 layers were partially etched out from TiO2/SiO2 2D PhCs fabricated by using autocloning. PL radiating normal to the surface was measured and large polarization dependence was observed. 相似文献
984.
Novel indolo[3,2-b]quinolines (1d-g), introduced at the 7-position with an N-glycosylamino group, were prepared and their antitumor activities against leukemia P388 in mice were examined. The N-Galactopyranosylamino derivative (1e) was a much more potent anti-leukemia compound (optimal dose = 25 mg/kg, T/C greater than 333%, cure 5/6) than lead compound 1a. 相似文献
985.
An improved analytical method is presented in which the reaction yield in the IR multiple-photon dissociation by a focused uniform beam is expressed in a generalized form as a function of fluence. The analytical solution is derived for a real focusing geometry by assuming the cumulative log-normal distribution (CLND) for the functional form of the dissociation probability vs. fluence. Also presented is a shortcut analytical method with simple and convenient algebraic expressions which approximate the exact analytical solution, thereby speeding up the analysis of experimental data. 相似文献
986.
Kunihiro Takeuchi 《Tetrahedron》2005,61(10):2601-2606
We theoretically investigate ring strains of tricyclic molecules or tricyclo[p.q.0.01,f]alkanes by calculating the strain energies as heat of the homodesmotic reactions. The strain energies are well correlated with the deformation from the tetrahedral configuration of the C1 atom. We theoretically design less strained tricyclic molecules by replacing some carbon atoms with phosphorus atoms. 相似文献
987.
Yasuo Oka Kentaro Kayanuma Satoshi Shirotori Akihiro Murayama Izuru Souma Zhanghai Chen 《Journal of luminescence》2002,100(1-4):175-190
Nanostructures of diluted magnetic semiconductors were fabricated to study novel magneto-optical properties that are derived from quantum confined band electrons interacting with magnetic ions. Quantum dots (QDs) of Cd0.97Mn0.03Se were grown by the self-organization on a ZnSe substrate layer. QDs of Zn0.69Cd0.23Mn0.08Se and quantum wires (QWRs) of Cd0.92Mn0.08Se and Zn0.69Cd0.23Mn0.08Se were fabricated by the electron beam lithography. A single quantum well (QW) of ZnTe/Zn0.97Mn0.03Te and double QWs of Cd0.95Mn0.05Te–CdTe were grown by molecular beam epitaxy. Magneto-optical properties and the formation and relaxation dynamics of excitons were investigated by ultrafast time-resolved photoluminescence (PL) spectroscopy. Excitons in these nanostructures were affected by the low-dimensional confinement effects and the interaction with magnetic ion spins. The exciton luminescence of the Cd0.97Mn0.03Se QDs shows the confined exciton energy due to the dot size of 4–6 nm and also shows marked increase of the exciton lifetime with increasing the magnetic field. The QDs of Zn0.69Cd0.23Mn0.08Se fabricated by the electron beam lithography display narrow exciton PL spectrum due to the uniform shape of the dots. The exciton luminescence from the QWRs of Cd0.92Mn0.08Se and Zn0.69Cd0.23Mn0.08Se shows the influence of the one-dimensional confinement effect for the exciton energy and the luminescence is linearly polarized parallel to the wire direction. The transient PL from the ZnTe/Zn0.97Mn0.03Te QWs displays, by the magnetic field, the level crossing of the exciton spin states of the nonmagnetic and magnetic layers and the spatial spin separation for the excitons. Cd0.95Mn0.05Te–CdTe double QWs show the injection of the spin polarized excitons from the magnetic well to the nonmagnetic QW. 相似文献
988.
We demonstrated, for the first time, 2.5-Gb/s SOA direct modulation in the wavelength-selectable DFB laser array. The SOA direct modulation was achieved in the wide tuning range of 22.7nm by selecting arrayed laser and tuning the temperature. 40-km transmission was also confirmed.. 相似文献
989.
990.
Two-beam coupling gain and speed of Cr-doped strontium barium niobate in the visible and near-infrared spectral regions are measured. It is found that the sample still exhibits the appreciable photorefractive gain in the near-infrared spectrum. Photorefractive parameters such as effective trap density, effective electrooptic coefficient and mobility · recombination-time product are obtained from the measurement. The photorefractive spectra of the coupling gain and speed in the sample are compared with those of Cr-doped KNSBN. 相似文献