Table of contents

20 March 1993, Volume 2 Issue 3 Previous issue    Next issue

GENERAL

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HAWKING EFFECT OF DIRAC PARTICLES IN VAIDYA-SCHWARZSCHILD-DE SITTER SPACE-TIME YANG CHENG-QUAN (杨成全), REN QIN-AN (任秦安), ZHAO ZHENG (赵峥) Acta Physica Sinica (Overseas Edition), 1993, 2 (3):  161-169.  DOI: 10.1088/1004-423X/2/3/001 Abstract ( 1031 )   PDF (133KB) ( 338 )   The solutions of the Dirac equation near the black hole event horizon and the universe horizon in the Vaidya-Schwarzschild-de Sitter space-time are given in this paper. Both the temperature of the Hawking radiation and the location of the evaporating black hole horizon and the universe horizon are determined exactly.

ATOMIC AND MOLECULAR PHYSICS

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ONE-BODY DENSITIES AND FEATURES OF THE STRUCTURE OF THE 2S+1Pe DOUBLY EXCITED HELIUM STATES DUAN YI-WU (段宜武), BAO CHENG-GUANG (鲍诚光) Acta Physica Sinica (Overseas Edition), 1993, 2 (3):  170-179.  DOI: 10.1088/1004-423X/2/3/002 Abstract ( 1042 )   PDF (246KB) ( 301 )   The qualitative features of electron-electron correlation of the 2S+1Pe doubly excited helium states have been investigated. The anisotropism of the electronic cloud has been shown. A comparison has been made between the S=1 and S=0 states. The structures among the states, which belong to the same rotorlike supermultiplet, have also been compared with each other.

ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS

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EXPERIMENTAL STUDY OF DIFFRACTIVE PROPERTIES OF WAVELENGTH-SIZED SINGLE GROOVES COATED WITH GOLD FILM Lü HUI-BIN (吕惠宾), R.E.BURGE, D. N. QU, X. YUAN Acta Physica Sinica (Overseas Edition), 1993, 2 (3):  180-189.  DOI: 10.1088/1004-423X/2/3/003 Abstract ( 1112 )   PDF (209KB) ( 369 )   We have gained a very comprehensive set of results for infrared diffraction (10.6 μm wavelength) from fabricated single grooves of reflection with widths in the range of 5μm to 65μm. The experimental results show that the diffraction can still occur when the groove width becomes comparable to or less than the wavelength of the probing light. Variations of the diffraction intensities have a very regular sinusoidal relationship with the polarization angle of the incident light; and the diffraction intensities are the maximal when the incident light is TM polarized. However, the diffraction intensities will be a minimum when the incident light is TE polarized; and the bigger the diffraction angle, the higher the rate of change of the diffractive intensity with increasing polarization angle of the incident light.

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A STUDY ON THE ULTRASONIC VELOCITY AND ATTENU-ATION IN NdFeB MAGNET WITHIN THE TEMPERATURE RANGE OF 80-300K(Ⅰ) LUO YANG (罗阳), HOU YU-MIN (侯玉敏), JI QI-GEN (计其根) Acta Physica Sinica (Overseas Edition), 1993, 2 (3):  190-197.  DOI: 10.1088/1004-423X/2/3/004 Abstract ( 1238 )   PDF (187KB) ( 417 )   The ultrasonic velocity V  and attenuation A of both longitudinal and shear waves in an anisotropic NdFeB magnet were measured over the temperature range from 80K to 300 K by the pulse echo method. The anisotropy of the ultrasonic wave propagating in a NdFeB magnet was observed. Anomalous changes in both V-T and A-T curves in the temperature range of 110-160 K were found, which might be due to the spin reorientation phase transition of Nd2Fe14B.

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A STUDY ON THE ULTRASONIC VELOCITY AND ATTENU-ATION IN NdFeB MAGNET WITHIN THE TEMPERATURE RANGE OF 80 - 300K (Ⅱ) LUO YANG (罗阳), HOU YU-MIN (侯玉敏) Acta Physica Sinica (Overseas Edition), 1993, 2 (3):  198-205.  DOI: 10.1088/1004-423X/2/3/005 Abstract ( 1479 )   PDF (181KB) ( 473 )   Based on the ultrasonic measurements of an isotropic NdFeB magnet in the temperature range of 77 - 300 K, it was found that the elastic parameters, such as Young's modulus E, and Poisson ratio v, change abruptly near the spin reorientation temperature Tsr. This indicates that soft mode emerges in the process of spin reorientation. Thermal hysteresis was observed during heating-up and cooling-down processes. Both Debye temperature and heat capacity were calculated, which suggests that the magnetic entropy of the Nd-sublattice is larger in easy-cone state than in easy-axis state.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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STUDIES ON THE BEHAVIOR OF THE INTERNAL VIBRATIONAL MODES IN (NH4)2TexSn1-xCl6 MIXED CRYSTALS ZHANG JIA-MING (张家明), SHEN XUE-CHU (沈学础), ZHOU TAO (周涛), XIE YUE-BAO (谢韵宝), XU YONG-CHEN (徐永晨), SHEN JUN (沈军), ZHOU PEI-ZHEN (周佩珍), J.PELZL Acta Physica Sinica (Overseas Edition), 1993, 2 (3):  206-212.  DOI: 10.1088/1004-423X/2/3/006 Abstract ( 1290 )   PDF (213KB) ( 384 )   The behavior of the internal lattice vibrational modes in (NH4)2TexSn1-xCl6 mixed crystals has been investigated by Raman scattering. All of the Raman-active [MX6]2- internal modes show two-mode property in the mixed crystals with compositions from x=0 to 1, and apart from the sample with x=0.5, their energy positions are composition-independent. Space group calculations including site symmetry considerations and frequency fittings describe a good force field model. It has been demonstrated that the composition-independent two-mode behavior may come from the strong clustering effect, rather than from the character of the gap and local modes of impurities in mixed crystals. For the sample with x=0.5, the two component elements seem to form a pseudo-periodic lattice structure.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

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PHOTOCONDUCTIVITY OF Cd0.7Mn0.3Se JIANG SHAN (姜山), SHEN XUE-CHU (沈学础), MA KE-JUN (马可军) Acta Physica Sinica (Overseas Edition), 1993, 2 (3):  213-219.  DOI: 10.1088/1004-423X/2/3/007 Abstract ( 1124 )   PDF (197KB) ( 373 )   The photoconductivity spectra of semimagnetic semiconductor Cd0.7Mn0.3Se have been measured at 50-300 K and in the wavelength range of 5500A to 8000A. It is found that the energy gap of Cd0.7Mn0.3Se changes with the temperature linearly, and the temperature coefficient (dEg/dT) is about -7×10-4 eV/K. A photoconductivity peak which is related to Mn2+ is also found. This peak is located around 1.85 eV, nearly unshifted with variation of the temperature. The possible transition mechanisms in Cd1-xMnxSe have been discussed in the light of group theory and crystal field theory, and the results are in good agreement with experiments.

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LINEAR TUNNELING CONDUCTANCE AND INELASTIC-TUNNELING MODEL LIU MEI (刘楣), XING DING-YU (邢定钰), DONG JIN-MING (董锦明) Acta Physica Sinica (Overseas Edition), 1993, 2 (3):  220-229.  DOI: 10.1088/1004-423X/2/3/008 Abstract ( 1331 )   PDF (332KB) ( 454 )   The inelastic-tunneling model can be used to explain the linear conductance background observed in tunneling in the high-Tc oxide super conductors. Introducing a parameter into the tunneling Hamiltanian to describe the strength of on-site Coulomb repulsion, we have derived an expression for the inelastic-tunneling conductance. We further discuss what form of the spin-fluctuation propagators in the inelastic-tunneling model can produce the linear tunneling conductance which would agree well with the experimental data.