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Acta Physica Sinica  
  Acta Physica Sinica--1982, 31 (11)   Published: 15 November 1982
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BRIEF REPORT

OBSERVATION OF DEFECTS IN β-SILICON CARBIDE EPITAXIAL FILM

GUO CHANG-LIN
Acta Physica Sinica. 1982, 31 (11): 1526 doi: 10.7498/aps.31.1526
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The defects in β-SiC epitaxial film are studied by means of etching method. The etchant used is the fused alkali hydroxide. The triangular etch pits with sharp bottom correspond to the dislocations. The perfect dislocations in β-SiC crystal are 73° dislocations and 60° dislocations. In β-SiC crystal there exists {111} boundary stacking fault formed by the contact of two β-SiC growing layer having different stacking sequences. The etching figure of the stacking fault is straight line running parallel to the 〈110〉 direction. The 60° dislocations can dissociate into two 1/6〈112〉 Schockley dislocat'ions and these two partial dislocations with a {111} stacking fault form an extensive dislocation. Three 1/6(110} stair-rod dislocations and three {111} stacking faults construct a stacking fault pyramid. Two parts of β-SiC film having positive and negative stacking sequence can produce a twin with the twin plane (111). The results of etching method and X-ray Laue method confirme the existence of the twin of this type.

SPECTRAL ANALYSIS BY MEANS OF IMAGE ADDITION AND SUBTRACTION TECHNIQUE IN WHITE-LIGHT PROCESSING SYSTEM

MU GUO-GUANG, WANG JUN-QING, FANG ZHI-LIANG
Acta Physica Sinica. 1982, 31 (11): 1534 doi: 10.7498/aps.31.1534
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Theory and experiments of a new spectrochemical analysis technique using a white-light image processing system are described. The spectrochemical analysis can be accomplished in three steps: (1) spatial encoding of two spectrograms to be tested, (2) color filtering at the Fourier plane in white-light optical image processor, and (3) colorimetric measurement in the output plane. Compared with existing methods of spectrochemical analysis, the present technique requires only one white-light processor and a single film of encoded film, therefore it is much simpler and more economical to use in practical applications.

SPECIAL POLARIZATION PHENOMENON OF MULTI-TRASVERSE MODE INTERNAL-MIRROR He-Ne LASER

ZHANG CHUN-PIN, ZHANG GUANG-YIN, LIU ZHI-GUO, BA EN-XU, Lü KE-CHENG
Acta Physica Sinica. 1982, 31 (11): 1541 doi: 10.7498/aps.31.1541
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We have observed some special polarization phenomenon of multi-transverse mode He-Ne laser. Elimination problem of mode degeneration was analysed based on Lamb theory of laser. Frequency difference between degenerate mode after eliminating degeneration was measured, and the observed phenomena were analysed theoretically.

WHITE-LIGHT STEREOPROJECTION WITH MODULATED SPECKLE ENCODING

MU GUO-GUANG, WANG ZHAO-QI, WU FA-XIANG, ZHANG NENG-YU
Acta Physica Sinica. 1982, 31 (11): 1547 doi: 10.7498/aps.31.1547
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Theory and experiment of a new image encoding technique using speckles modulated by different slit pupil function are described. Compared with current grating encoding, the advantages of the new technique are that there is no necessity to reprint the negative transparency into a positive one, operation is simple, and resolution is high enough. Especially in multi-signal parallel processing the Moire fringes that easily appear in grating encoding do not appear in the speckle encoding. As an example, the experimental result of white-light stereoprojection utilizing speckle encoding is given.

ON THE VECTOR-TENSOR INTERACTION OF GRAVITATION

ZHANG YUAN-ZHONG, GUO HAN-YING
Acta Physica Sinica. 1982, 31 (11): 1554 doi: 10.7498/aps.31.1554
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In the paper, by using the equation of motion a particle, we show that the antig-ravity exist in the vector-tensor model of gravitation. Thus the motion of a particle deviates from the geodesic equation. In Newtonian approximation and weak gravitational field, acceleration of a particle in a spherically symmetric and astatic gravitation field is zero. The result is obviously not in agreement with gravitational phenomena.

STRUCTURE OF TRANS-DICHLOROBIS (L-ETHYL-PHENYL-ALANATE) PLATINUM (II)

YANG QING-CHUAN, TANG YOU-QI, TANG WEN-XIA, YAN KE
Acta Physica Sinica. 1982, 31 (11): 1558 doi: 10.7498/aps.31.1558
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[Pt(C11H15NO2)2Cl2] is monoclinic, with space group P21H. Z=2, and lattice parametes α=13.555(6)?, b=6.487(3)?, c=15.588(5)?, β=109.42(3)?. The structure was determined by heavy-atom method and refined by "blocked cascade" full-matrix leastsquare refinement technique to R=0.0617, RwH=0.0575. The atom Pt(II) has approximate square coordination, with bond lengths Pt-N 2.065(14), 2.084(14)?; PtCl 2.285(7), 2.312(8)?. The structure contains layers of molecules hydrogen bonded together through N-H……O.

MEASUREMENT OF HYDROSTATIC PRESSURE EFFECT ON OPTICAL ABSORPTION EDGE OF AMORPHOUS As2S3 USING HIGH-PRESSURE MICROSPECTROSCOPIC SYSTEM

ZHA CHANG-SHENG, GUO CHANG-XIN
Acta Physica Sinica. 1982, 31 (11): 1564 doi: 10.7498/aps.31.1564
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Shift of optical absorption edge of amorphous As2S3 with increasing hydrostatic pressures up to 66 kbar has been quantitatively measured by means of high-pressure mic-rospectroscopic system in conjunction with gasketed diamond anvil cell under room-temperature. The method of ruby fluorescence shift technique was adopted for pressure calibration. Amorphous As2S3 thin film samples a few micrometers in thickness were prepared by vacuum evaporation. Under our experimental conditions, neither the light of 4416? He-Cd laser used for excitation of the ruby gauge, nor that of the Br-W lamp for measurement of light transmission, showed any detactable influence on the optical properties of the sample. Rapid red-shift of optical absorption edge with increasing pressure was observed, Eg dropped from 2.58 eV to 1.95 eV between 1 bar and 66 kbar. An empirical formula of experimental data was obtained. The relationship of absorption edge and pressure is as follows: Eg(P)=Eg(0)-1.31×10-3P-3.91×10-4P2+4.04×10-6P3. It is noteworthy that the dependence of |dEg/dP| upon pressure was increasing at first and then decreasing gradually to saturation at high pressure. This result shows something different from privious one obtained by Weinstein et al. The origin of the difference was discussed.

QUANTUM THEORY OF A DAMPED HARMONIC OSCILLATOR SIMULATING LASER OPEN SYSTEM

TAN WEI-HAN, WANG XUE-WEN, XIE CHENG-GANG, ZHANG GUAN-MEI
Acta Physica Sinica. 1982, 31 (11): 1569 doi: 10.7498/aps.31.1569
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We have analysed the quantization schemes presented in references [1, 2] for a damped harmonic oscillator and found out that there are some defects in volved in these schemes. In order to remedy these defects, we assume the coordinate system fluctuating with a velocity g(t) in addition to damping force f(t) proportional to the velocity and suggest a method of quantization for this system based on the full quantum theory of lasers. It is proved that the usual Heisenberg relation xp-px=ih can be maintained, but the quantum term in statistical average value of physical variable does not damp as shown in reference [1].

SELF-CONSISTENT CORRELATED PERCOLATION

ZHANG ZHAO-QING
Acta Physica Sinica. 1982, 31 (11): 1576 doi: 10.7498/aps.31.1576
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The critical properties of a quenched site-correlated percolation system is treated by real-space renormalization group method. We chose the nearest-neighbour short-range order a as the correlation parameter. By treating the correlated probability self-consistently, we found, in two dimension, there is only one nontrivial physical fixed point and the correlation is an irrelevant parameter at random percolation fixed point, which is consistent with other correlated percolation models.
CONTENT

INTERNAL FRICTION ASSOCIATED WITH MARTENSITIC AND PREMARTENSITIC PHASE TRANSFORMATION IN THE kHz AND THE MHz RANGE

SHEN HUI-MIN, XU ZI-RAN, ZHU JIN-SONG, YANG ZHAO-JIN, WANG YE-NING
Acta Physica Sinica. 1982, 31 (11): 1449 doi: 10.7498/aps.31.1449
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The internal friction (49kHz), ultrasonic attenuation (4-82 MHz) and Young's modulus associated with martensitic transition (MT) were measured in AuCd alloys containing 46.1 at%, 47.5 at% and 52.5 at% Cd respectively.The internal friction due to MT in the kHz range was confirmed as the hysteresis loss just the same as we have disclosed in the Hz range. The origin of internal friction peak was explained by elastic softening and the interaction of the interface dislocations with point defects. But the ultrasonic attenuation in the MHz range is frequency dependent, this implies that there exist components of resonance and relaxation loss contributed by viscous motion of dislocations.In addition, the isothermal martensitic transition peak and the premartensitic phase transformation peak in AuCd alloys were observed as well.

PERFORMANCE EVALUATION TECHNIQUES OF ANECHOIC CHAMBERS

ZHANG ZHONG-PENG
Acta Physica Sinica. 1982, 31 (11): 1457 doi: 10.7498/aps.31.1457
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This paper describes the concept for the characteristic parameters of the microwave anechoic chambers, the principle and method of measurements, and the treatment of experimental data as well as some points to be noticed. The concept of "the equivalent reflectivity" is introduced for the purpose of using the theory of transmisson line to derive some formulas and curves which may be useful in treatment of experimental data of natural reflectivity level. Finally, some typical experimental results are presented.

CORRELATED WAVE FUNCTION THEORY FOR METAL SURFACES (Ⅰ)——THEORETICAL FRAMEWORK

SUN XIN, LI TIE-CHENG, G. W. WU
Acta Physica Sinica. 1982, 31 (11): 1466 doi: 10.7498/aps.31.1466
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In this paper, we present a theoretical framework about correlated wave function for metal surfaces. The trial wave function for surfaces consists of a determinant of model single particle orbitals which are solutions of a variational potential with a consistent special symmetry, and a Feenberg-Jastrow pair correlation factor. In the "jel-lium model", we obtain expressions of ground state energy of metal surfaces. For the case without Feenberg-Jastrow factor in the wave function, we also obtain the expression for electron density distribution.

CORRELATED WAVE FUNCTION THEORY FOR METAL SURFACES (Ⅱ)——PRACTICAL CALCULATION

SUN XIN, LI TIE-CHENG, G. W. WU
Acta Physica Sinica. 1982, 31 (11): 1474 doi: 10.7498/aps.31.1474
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Surface energies, density profiles and Gibbs surfaces are calculated over a wide range of electron densities in the "jellium" model on the basis of previous theoretical framework. The electron density distributions are obtained by solving the Chakravarty-Woo integral equations for inhomogeneous electron liquids. Because of the long range Coulomb interaction, a series of divergences appear in the integral equations and the energy expression, but they are proved to cancel exactly. Surface energies obtained are close to experimental data over the domain of density of metals.

THE CLOSED TIME PATH GREEN'S FUNCTIONS AND THE THEORY OF NONLINEAR RESPONSE (Ⅰ)

WANG WAI-TONG, LIN ZHONG-HENG, SU ZHAO-BIN, HAO BAI-LIN
Acta Physica Sinica. 1982, 31 (11): 1483 doi: 10.7498/aps.31.1483
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By using the generating functional and the transformations for different forms of the closed time path Green's functions, the general equations on nonlinear response are derived. On the basis of the algebraic identities, KMS condition, time reversal inva-riance and spectral representation, the general considerations for seeking the relations among many-point functions are suggested.

THE CLOSED TIME PATH GREEN'S FUNCTIONS AND THE THEORY OF NONLINEAR RESPONSE (Ⅱ)

WANG WAI-TONG, LIN ZHONG-HENG, SU ZHAO-BIN, HAO BAI-LIN
Acta Physica Sinica. 1982, 31 (11): 1493 doi: 10.7498/aps.31.1493
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By using the results of our previous paper, the linear fluctuation-dissipation theorem are formally generalized to nonlinear case described by n-point correlation and response functions.

RELATIVISTIC QUANTUM MECHANICS FOR SCALAR PARTICLES AND SPINOR PARTICLES IN THE BELTRAMI-DE SITTER SPACETIME

LI GUANG-YI, GUO HAN-YING
Acta Physica Sinica. 1982, 31 (11): 1501 doi: 10.7498/aps.31.1501
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Following the procedure to transmute the relativistic theory of classical particles to quantum theory in the Minkowski spacetime, we have proposed a scheme to establish relativistic wave equations for scalar particles and spinor particles in the Beltrami-de Sitter spacetime. It is shown that these equations are invariant under the transformations of the de Sitter group and are just the Klein-Gordon equation and the Dirac equation in the Beltrami-de Sitter spacetime respectively. The eigenfunctions and the corresponding discrete eigenvalues of these equations on the metric of a family of space-like simultaneous hypersurfaces in the Beltrami-de Sitter spacetime have been obtained.

DISLOCATIONS IN α-SILICON CARBIDE SINGLE CRYSTAL

GUO CHANG-LIN
Acta Physica Sinica. 1982, 31 (11): 1511 doi: 10.7498/aps.31.1511
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The dislocations in cc-SiC single crystal are studied by means of etching method and X-ray topographic method. The etchant used is the fused alkali hydroxide. The one-to-one correspondence between the etch pits with sharp bottom and the dislocations are confirmed. Because of the Burgers vector of the screw dislocations in [0001] direction are much larger than that of the edge dislocations, one can distinguish the screw dislocations from the edge dislocations according to the depth of etch pits. The correspondent relation between the shape of etch pits and the crystal structure of polytype is given. The relationships between the pattern of growth spiral on surface and the dislocations as well as the movement of dislocations are studied. X-ray topography shows that a lot of dislocations in cc-SiC are on the base plane (C plane). The growth dislocations nucleate at the crystal root and extend along the direction of crystal growth passing through the whole crystal in the crystal growth process, so the dislocation lines are always along the [1010] and [1120] direction. The dislocations in cc-SiC crystal can be observed completely only when both the etching method and X-ray topographic method are employed.
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