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991.
G. Halambalakis N. Rousseau O. Briot S. Ruffenach R.L. Aulombard P.R. Edwards K.P. ODonnell T. Wojtowicz P. Ruterana 《Superlattices and Microstructures》2004,36(4-6):721
We have studied the optical properties of Eu doped GaN thin films. We have grown high quality Eu doped GaN thin films by using Gas Source Molecular Beam Epitaxy (GSMBE), with 1.4% Eu concentration. The Full Width at Half Maximum (FWHM) of the X-ray diffraction in an omega scan was found to be 288 arcsecs. Low Eu concentration (0.08%) doped GaN thin films were grown, where Eu-related photoluminescence at 622 and 613 nm was detected using above band-gap excitation at 2 K. For high Eu concentration of 30% GaN:Eu crystal photoluminescence (PL) and cathodoluminescence (CL) spectra show strong and intense transitions at 622 and 664 nm, but also at 593 nm for CL spectra, with a similar transition observed from the low Eu concentration sample. 相似文献
992.
The propagation properties of decentered twisted Gaussian Schell-model (DTGSM) beams passing through a misaligned first-order optical system are studied. The explicit expressions for the cross-spectral density function and Wigner distribution function of the output beam are derived, which retain their form unchanged. It is shown that the DTGSM beams preserve their closed property. The second-order moments matrix and the Wigner distribution function evolve with the usual laws, whereas the first-order moments matrix varies, as if a ray passes through such system. The propagation of DTGSM beams through an aligned first-order optical system is treated as the limiting case that corresponds to the vanishing misalignment parameters. 相似文献
993.
Shaidarova L. G. Gedmina A. V. Budnikov G. K. 《Russian Journal of Applied Chemistry》2003,76(5):755-761
A procedure was developed for analysis of ascorbic acid with a carbon glass electrode coated with a palladium-modified poly(2-vinylpyridine) film. 相似文献
994.
L. V. Stepanova 《Journal of Applied Mechanics and Technical Physics》2008,49(1):142-147
This paper discusses the problem of finding the eigenvalue spectrum in determining the stress and strain fields at the tip
of an antiplane-shear crack in a power-law material. It is shown that the perturbation method provides an analytical dependence
of the eigenvalue on the material nonlinearity parameter and the eigenvalue of the linear problem. Thus, it is possible to
find the entire spectrum of eigenvalues and not only the eigenvalue of the Hutchinson-Rice-Rosengren problem.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 1, pp. 173–180, January–February, 2008. 相似文献
995.
B. Champagnon C. Martinet M. Boudeulle D. Vouagner C. Coussa T. Deschamps L. Grosvalet 《Journal of Non》2008,354(2-9):569-573
Normal silica glass is usually referred to as low density amorphous silica as it can be converted to high density amorphous silica by a hydrostatic pressure (polyamorphic transition). In this work in situ Raman experiments are performed in a diamond anvil cell up to 18 GPa. The pressure effects on the structure of silica after successive compression decompression experiments are analyzed. The mode Grüneisen parameters corresponding to the elastic compression of high density amorphous silica are obtained and compared with those of normal silica. A reorganization of the high density amorphous silica below 3 GPa is evidenced. 相似文献
996.
A theoretical approach was made to find out a complete fluorine incorporation zone on a ternary diagram which serves as a useful graphical representation to select the flows of the supplied reagents for incorporation of the suitable amount of fluorine into cladding glass of optical fiber preform made by the MCVD process using CCl2F2 as a source of fluorine under oxygen abundance, oxygen deficiency and intermediate oxygen state conditions. The possible mechanism for incorporation of fluorine into cladding glass of optical fiber is also evaluated on the basis of the thermodynamical data. The fluorine incorporation mechanism in silica glass by the MCVD process is found to be dependent on the CCl2F2/SiCl4 ratio in the input gas mixture. Fluorine doping is found to be effective for removing the strained Si–O–Si bonds, which govern the optical transparency in deep ultra-violet (DUV) and vacuum ultra-violet (VUV) regions. The maximum refractive index depression of ?0.5 × 10?3 is obtained with incorporation of fluorine into silica cladding glass by the MCVD process using CCl2F2 as a dopant precursor with suitable flow of SiCl4 vapor along with O2 through backward deposition pass. The structure of fluorine doped silica glass preform samples containing 1.70–1.79 mol% fluorine incorporated by the MCVD process based on the analyses of 19F MAS spectra done by high-resolution 19F NMR spectroscopy reveal the presence of two distinct types of fluorine environments. The majority of the fluorine environments are formed in SiO1.5F polyhedral and less abundant species is observed to be highly unusual, yielding a fivefold coordinated silicon of the type SiO2F polyhedral which become increased with increasing the fluorine content. 相似文献
997.
Specific features of the formation of submicron (70–300 nm) inclusions in Ti:sapphire (Al2O3:Ti) grown in a carbon-containing medium have been investigated. These inclusions are caused by deviation from the melt stoichiometry and are formed during the melt-crystal phase transition. These defects are submicropores containing excess aluminum and its suboxides; they can be destroyed by thermal loading of a crystal. 相似文献
998.
Elastic rod models provide a means to interpret single molecule DNA experiments as well as predict DNA behavior under physiological conditions. Here we use an elastic rod model to predict the stability boundary (critical torque vs. applied tension) for single molecule DNA experiments in which the molecule is subjected to applied tension and twist. We discuss the shortcomings of the usual isotropic rod model. We then derive a consistent non-linear material law from the general representation for a hemitropic (chiral) rod. Finally, we present results of a standard bifurcation analysis predicting the stability boundary. We find results from the non-linear hemitropic rod to match the data closely. 相似文献
999.
B. B. Troitskii L. V. Khokhlova V. N. Denisova M. A. Novikova A. E. Golubev A. V. Arapova A. A. Zaitsev 《Russian Journal of Applied Chemistry》2008,81(7):1252-1257
Organic-inorganic composites of poly(methyl methacrylate) with alkoxysilane hydrolyzates form transparent films. Their thermal and oxidative thermal degradation were studied by differential scanning calorimetry and thermogravimetric analysis. 相似文献
1000.