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1.
《Ultrasonics》1986,24(2):88-92
The velocity and attenuation of hypersonic waves propagating along the [100] or [110] axis of undoped and Cr-doped Bi12GeO20 have been measured at frequencies from 0.76 to 1.65 GHz and at temperatures of 4.5, 24, 77 and 293 K. The second-order elastic constants and Debye temperature have been calculated from these results. The measurements and the results of the calculations are used to interpret the attenuation in terms of collisions between low-energy phonons, constituting the sound wave, and thermal phonons. The thermal-phonon lifetime and Grüneisen constant have been estimated for undoped and doped material. 相似文献
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Yoshinobu Itoh 《Optics Communications》1973,8(4):387-389
An incoherent-to-coherent converter is constructed with a bismuth germanium oxide crystal. Several experiments are carried out with emphasis on the spatial resolution. It is found that the line width of the read-out image is approximately proportional to the logarithm of the write-in pulse duration, and that longer exposures cause the read-out image to deteriorate sooner. Several ways to increase the spatial resolution of the converter are discussed. 相似文献
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J. Zelenka 《Czechoslovak Journal of Physics》1978,28(2):165-169
The elastic and piezoelectric constants and their temperature coefficients of bismuth germanium oxide have been determined. All of the elastic and piezoelectric constants were obtained from dynamic measurements of piezoelectrically driven narrow bars and thin plates at the temperature 22 °C. The temperature coefficients were measured on the same resonators in the temperature range from 16 °C to 70 °C. The thermal expansion measured in the temperature range from 50 °C to 200 °C is also given.The author wishes to acknowledge the help rendered by Professor Ing. Dr.Jaroslav Stank in connection with the measurement of the thermal expansion coefficient and by R.Trepera in the course of the preparation of the measured resonators. 相似文献
6.
Superbroadband 1310 nm emission from bismuth and tantalum codoped germanium oxide glasses 总被引:4,自引:0,他引:4
Near-infrared broadband emission from bismuth-tantalum-codoped germanium oxide glasses was observed at room temperature when the glasses were pumped by an 808 nm laser diode. The emission band covered the O, E, S, C, and L bands (1260-1625 nm), with a maximum peak at approximately 1310 nm, a FWHM broader than 400 nm, and a lifetime longer than 200 micros. The observed broadband luminescence was attributed to bismuth clusters in the glasses. Bismuth-tantalum-codoped germanium oxide glass might be promising as amplification media for broadly tunable lasers and wideband amplifiers in optical communications. 相似文献
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《Nuclear Physics A》1987,475(2):361-379
Scattering of 31.5 MeV α-particles from the stable even Ge isotopes has been studied with an energy resolution of 15–20 keV FWHM. Angular distributions were measured for excitation energies of up to 5.2 MeV. Most of the levels are well described by collective DWBA calculations with vibrational model form factors. An implicit folding procedure was used to derive isoscalar transition rates. The distribution of the isoscalar multipole strength reveals an increasing fragmentation with increasing neutron number. A detailed comparison with the spectroscopic results of a recent (p, p′) study is made. 相似文献
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Values of dielectric constant (ε′) and loss factor (ε″) have been experimentally determined for binary liquid mixtures of ethyl methyl ketone+ethylenediamine and methyl isobutyl
ketone+ethylenediamine at 9.44 GHz microwave frequencies at 30°C. The values ofε′ andε″ have been used to evaluate the molar polarization, apparent polarization and the excess permittivities. Excess refractive
index, viscosity and activation energy of viscous flow have also been estimated. These parameters have been used to explain
the formation of 1:1 complexes for both the systems. 相似文献
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Vladimir Skarka Marina M. Lekić Aleksander G. Kovačević Boban Zarkov Nebojša Ž. Romčević 《Optical and Quantum Electronics》2018,50(1):37
We present here the experimental, theoretical, and numerical investigations of Kerr solitons generated by self-organization in black and yellow high quality bismuth germanium oxide (Bi12GeO20) single crystals. A picosecond laser beam of increasing power induces competing cubic and quintic nonlinearities. The numerical evolution of two-dimensional complex cubic-quintic nonlinear Schrödinger equation with measured values of nonlinearities shows the compensation of diffraction by competing cubic and quintic nonlinearities of opposite sign, i.e., the self-generation and stable propagation of solitons. Experiments as well as numerical simulations show higher nonlinearity in the black Bi12GeO20 than in the more transparent yellow one. 相似文献
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Processes of the inelastic magnetic and weak scattering of tritium-beta-source antineutrinos on the bound electrons of a germanium atom are considered. The results obtained by calculating the spectra and cross sections are presented for the energy-transfer range between 10 eV and 18 keV. 相似文献
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J. Sládková 《Czechoslovak Journal of Physics》1968,18(6):801-806
The optical constants, i.e. the refractive index and thickness, were determined for thin oxide films which were produced by heating single-crystal samples of germanium to temperatures ranging from 450° C to 600° C. The ellipsometric method was used to determine the thicknesses and the refractive indices of the films.
The paper is dedicated to the memory of Dr. A. Vaíek, Professor of the J. E. Purkyn University in Brno, who died on Nevember 16, 1966. 相似文献
14.
Tensile-strained germanium films in Ge/GeSn/Si/GeSnSi multilayer heterostructures grown by molecularbeam epitaxy on Si(001) substrates are investigated by Raman spectroscopy. Biaxial tensile strains in the films reach 1.5%, which exceeds values previously obtained for this system. Splitting of frequencies of long-wavelength optical phonons is experimentally observed; i.e., the shift of the frequency of the singlet induced by biaxial tensile strains is larger than the shift of the frequency of the doublet in agreement with calculations. The strain-induced shift of Raman scattering peaks from two-phonon scattering in germanium is also detected. 相似文献
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Elastic constants measured by Brillouin light-scattering experiments were compared with results estimated from the pulse-echo-overlap method for the ultrasonic frequency to find dispersion in their values. In this way Brillouin hypersonic experiments complete the ultrasonic results. The present investigation includes a careful analysis of the accuracy of the results. The measured values of elastic constants suggest a weak dispersion in acoustic wave velocities. However, given the magnitude of the experimental errors, it is difficult to conclude about the dispersion. 相似文献
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Yu. M. Smirnov 《Journal of Applied Spectroscopy》1991,55(6):1263-1268
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 6, pp. 988–993, December, 1991. 相似文献
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采用基于密度泛函理论框架下的第一性原理计算,研究了不同浓度N型掺杂锗的电子结构和光学性质.掺杂元素分别为磷和铋,并对掺杂后的电子态密度和光学性质进行计算、分析.计算结果表明:N型掺杂会使得费米能级向导带方向移动.在低能区段,介电函数、折射率和吸收系数都受到影响,但到高能区后只有消光系数和吸收系数会被影响;反射率在整个能区都受影响,在中能区掺杂会使反射率提高,在低、高能区会减弱反射率;对损失函数的影响是掺杂浓度越高、损耗峰越小、峰值出现处能量越高.研究结果对N型掺杂半导体锗的光学应用具有一定的指导意义,可以根据上述结论有针对性地调节掺杂浓度和能量范围. 相似文献
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The diffusion of water through an oxide film on germanium was investigated by measurement of the surface conductivity, and a relation was found between the coefficient of diffusion and the humidity of the ambient medium. 相似文献
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《Physics letters. [Part B]》1987,194(2):317-320
s-channel unitarity strongly constrains the amount of inelastic diffraction at collider energy, and allows to predict its dependence on the impact parameter and to compute useful upper bounds at even higher energies. 相似文献
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A derivation by Byron of the Glauber wavefunction for inelastic scattering without the explicit introduction of the nonmoving bound particle assumption is shown in fact to have this restriction implicitly. 相似文献