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Acta Physica Sinica  
  Acta Physica Sinica--1991, 40 (8)   Published: 15 August 1991
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CLASSICAL AREA OF PHENOMENOLOGY

QUANTUM THEORY OF TWO-PHOTON LASER

WANG ZHI-CHENG
Acta Physica Sinica. 1991, 40 (8): 01259 doi: 10.7498/aps.40.1259
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Starting from the microscopic Hamiltonian of the three-level model and making use of the slowly varying amplitude approximation and the two-photon rotating wave approximation, we derive an effective Hamiltonian for the two-level two photon model under conditions where the two-photon process dominates the other radiartive processes, so that an exact relation between the three-level model and the two-level two-photon model is established. The effective Hamiltonian includes a term come from the optical Stark effect which was neglected in the conventional treatment. The coefficient of this term may have the same order of magnitude as the effective coupling constant. Based on this effective Hamiltonian, the standard method of Haken's laser theory is applied to study the threshold, the mean photon number, the self-induced frequency shift, the photon statistics and the fluctuation in steady states. Results are compared with previous ones which neglect the Strk effect.

SQUEEZING AND PHOTON STATISTICS

LIU ZHENG-DONG, LIU SAN-QIU
Acta Physica Sinica. 1991, 40 (8): 01263 doi: 10.7498/aps.40.1263
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In this paper, the relation between squeezing and photon statistics is studied. The photon statistics of cavity field can be changed by injecting atoms at such a low flux thar at most one atom at a time is present inside the lose-free cavity, deeper squeezing may be achieved.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

STRUCTURAL CHANGES IN AMORPHOUS Pd80Si20 AND Pd77.5Cu6Si16.5 ALLOYS CAUSED BY NEUTRON IRRADIATION

WU ZI-QIANG, WU GUO-AN, XIAO KE-QIN, DONG YUAN-DA, HE YI-ZHEN
Acta Physica Sinica. 1991, 40 (8): 01298 doi: 10.7498/aps.40.1298
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The present work is to study effects of neutron irradiation on the structure of amorphous Pd80Si20 and Pd77.5Cu6Si16.5 alloys by using X-ray diffraction techniques, differential scanning calorimertry (DSC) and internal friction measurements. The irradiation appeared to produce obvious changes in the pair correlation function g(r) and radial distribution function RDF (r). The increases of crystallization temperature (Tx) and enthalpies of two specimens were found by DSC measurements after irradiation. The results of internal friction measurement show that the internal friction of the irradiated Pd80Si20 alloy is higher than that of the unirradiated in the temperature range of Tp. The structure changes before and after neutron irradiation are discussed in terms of the concepts of density fluctuation defects (p) and shear stress fluctuation defects (τ).

JAHN-TELLER EFFECT AND THE STRUCTURAL PHASE TRANSITIONS IN LiNbO3 (I)

WU JIAN-BIN, WANG ZHI-CHENG
Acta Physica Sinica. 1991, 40 (8): 01303 doi: 10.7498/aps.40.1303
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Starting from the Jahn-Teller-like effect, we studied theoretically the problem of structu-ral phase transition of LiNbO3 at 75℃. The results are qualitatively consistent with experimental data.

JAHN-TELLER EFFECT AND THE STRUCTURAL PHASE TRANSITIONS IN LiNbO3 (II)

WU JIAN-BIN, WANG ZHI-CHENG
Acta Physica Sinica. 1991, 40 (8): 01313 doi: 10.7498/aps.40.1313
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Based on the assumption of our previous paper (I), we have calculated the thermal expansion coefficients of LiNbO3 along c and b axes respectively. The results are consistent with the experiments.

JAHN-TELLER EFFECT AND THE STRUCTURAL PHASE TRANSITIONS IN LiNbO3(III)

WU JIAN-BIN, WANG ZHI-CHENG
Acta Physica Sinica. 1991, 40 (8): 01320 doi: 10.7498/aps.40.1320
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In this paper, the ferroelectric couplings in LiNbO3 have been studied by raking account of the Jahn-Teller effect of NbO6-octahedra. Based on the pseudo-spin model, we qualitatively interpret the 10 phase transitions in LiNbO3 in the temperature range of 290-1221℃.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

MONTE-CARLO STUDIES OF RADIATION DAMAGE INDUCED BY FUSION (II)——SPUTTERING

SHAO QI-YUN, CHEN JIAN-XIN, WU SHI-MING, PAN ZHENG-YING, HUO YU-KUN, GAO XING-HUA
Acta Physica Sinica. 1991, 40 (8): 01244 doi: 10.7498/aps.40.1244
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By means of the monte-carlo method based on the binary collision approximation, this paper investigates sputtering caused by fusion α-particles at the first wall of stainless steel (Fe0.73Cr0.18Ni0.09). The parameters adjusted in accordance with a comparison of the calculated and measured sputtering yields of the elements Fe, Cr and Ni were used to study the partial sputtering yields, energy distribution, angular distribution and depth distribution of origin of the sputtered particles, as well as the dependence of those quantities with the angles of incidence. The results show that by taking into account the energy and incidence angle distribution, the averaged sputtering yield of α-panicles in stainless steel is about 0.375, and the higher energy component of α-particle plays minor role so far as sputtering is concerned.

THEORETICAL INVESTIGATION ON THE PRESSURE BEHA-VIOR OF NITROGEN BOUND EXCITONS IN GaP AND GaAs1-xPx

ZHANG YONG, ZHENG JIAN-SHENG, WU BO-XI
Acta Physica Sinica. 1991, 40 (8): 01329 doi: 10.7498/aps.40.1329
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Using a Koster-Slater one band-one-side approximation, the relationship between the pressure behavior of nitrogen bound excitons and the band structure is investigated in GaP and GaAs1-xPx. An analytical expression is found to be a good approximation for the pressure coefficient of the deep impurity state. The pressure coefficients of N and NNi bound exciton states are calculated in GaP and GaAs0.17P0.83. A tentative new assignment which agrees with experiments in both ordering of levels and pressure coefficients is given for nitrogen pair configurations.

SUPERCONDUCTIVITY AND CARRIER CONCENTRATION OF SINGLE PHASE (Bi,Pb)2Sr2Ca2Cu3Oy SAMPLES

CHENG XIANO-AI, HE ZHFN-HUI, WANG SHUN-XI, SHA JIAN, CHEN XIAN-HUI, ZHANG QI-RUI, SUN YU-PING, YIN HUA-QING, DU JIA-JU
Acta Physica Sinica. 1991, 40 (8): 01339 doi: 10.7498/aps.40.1339
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Single phase (Bi, Pb)2Sr2Ca2Cu3Oy samples have been prepared with different heat treatments. X-ray diffraction, the dependence of resistance on temperature, ac. susceptibility and Hall coefficient have been investigated. We find that all samples are of 2223 single phase, the midpoint superconducting transition temperatures (Tc) are above 100K, and Tc increases mo-notonically with the carrier concentration (nH). The experimental results show that the conditions of heat treatment affect the phase structure, Tc and nH for the Bisystem. We propose that Tc and nH. of the Bi-system are closely related to oxygen content, local composition and structure perfection.

INVESTIGATION OF 3d TRANSITION METALS BY IONIZATION LOSS SPECTROSCOPY

ZHANG QIANG-JI, CHEN NAI-QUN, HUA ZHONG-YI
Acta Physica Sinica. 1991, 40 (8): 01344 doi: 10.7498/aps.40.1344
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A simple method has been developed in our laboratory, namely, lonization Loss Spectros-copy (ILS) for unoccupied DOS measurement which can be performed with existing Auger electron spectroscopy apparatus.The results of spin-orbit splitting and binding energy obtained by ILS are in excellent agreement with that of ESCA. The ILS spectra of 3d transition metals, Ti, Cr, Ni, Cu have been measured. The typical integral spectra exhibit a peak-like shape with different intensity and width which reflects the width of the unoccupied DOS. Since the unoccupied 3d DOS of Cu is zero, the ILS spectrum of Cu measured is shown by a step-like structure resulting from the flat, narrow 4s DOS.

VARIATION OF HOLE CONCENTRATION INDUCED BY ELEMENT SUBSTITUTION AT Y AND Cu(I) SITES IN YBa2Cu3Oy SYSTEM

ZHAO YONG, HE YE-YE, ZHANG HAN, ZHUGE XIANG-BIN, XU ZHU-AN, LI TAO-YU, ZHANG QI-RUI, TANG XIAO-MING, ZHAO PENG-CHENG
Acta Physica Sinica. 1991, 40 (8): 01349 doi: 10.7498/aps.40.1349
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The origin and the regularity of the variation of hole concentration as well as the crystal structure and superconducting critical temperature versus the doping contents of Co for Cu (I) and Ca for Y in YBa2Cu3Oy are studied in this paper. The results reveal that the pattern in which the hole concentration in Cu-O sheets, Psh, is influenced greatly by the substitution depends upon the different substituting elements as well as the different atomic sites, e.g. the decrease of Psh in system substituted by Co for Cu (I) is from filling and localizing of holes, but the increase of Psh in system of Ca replacing for Y is due to the delocalization effect of the holes. When Y and Cu (1) are substituted simutaneously with Ca and Co respectively, the generation instead of the localization effect cf the holes is important for the change of Psh. In addition, the relationship between Psh and Tc is discussed.

THE FORMATION AND THE MAGNETIC PROPERTY OF Fe, Co AND Ni FINE METAL PARTICLES

LI HUA, GONG WEI
Acta Physica Sinica. 1991, 40 (8): 01356 doi: 10.7498/aps.40.1356
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Fine particles of Fe, Co and Ni with average diameters from 120? to 800? were prepared by a gas evaporation method in the atmosphere of argon or nitrogen. We revealed that homogeneous nucleation growth was the dominant growth mechenism of the particles prepared at low pressure (<3 Torr). The zigzag chains could be explained by the magnetic connection of particles when each particld had a multi- domain structure, and the straight chains when each particle had a single domain. The X-ray diffraction revealed that the crystal structure of Fe and Ni fine particles was the same as the bulk materials and the crystal strcuture of Co fine particles with average diameter from 200? to 300? was f.c.c. which differed from h.c.p.of bulk cobalt at room temperature. When the diameter of the particles was about 210?, 200? and 320?, which is nearly the single domain size of Fe. Co and Ni particles, the maximum corecivity of Fe, Co, Ni fine particles was 1000 Oe, 1500 Oe and 450 Oe at room temperature respectively. The saturation magnetization decreased with the decrease ef panicle size due to the increase of the volume percent of the oxide layers and the numbers of the superparamag-netic particles. A noneollinear configuration of the magnetic moments existed in oxide surface layers for fine particles.

MAGNETIC ANISOTROPY AND SPIN SPECTRA IN Ni-FeCr MULTILAYER FILMS

CHEN HUI-YU, LUO YOU-QUAN
Acta Physica Sinica. 1991, 40 (8): 01364 doi: 10.7498/aps.40.1364
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Ni-FeCr multilayer films were prepared by diode sputtering technique. These multilayer films exhibit magnetic uniaxial anisotropy that is shown by fitting the anglar dependence of ferromagnetic uniform resonance field. The anisotropy energy could be expressed by EK=K1sin2θ+K2sin4θ, where K2/K1≈0.59. However the behavior of surface mode suggests that che surface and interface anisotropy of these multilayer films is not of the uniaxis type. We consider that is caused by the exchange coupling at the surface and interface.
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

STUDIES ON DEALUMINIZATION PROCESS OF FAUJASITE BY MONTE-CARLO METHOD

JIN QING-HUA, SUN PING-CHUAN, WANG JING-ZHONG, LI ZI-YUAN, DING DA-TONG
Acta Physica Sinica. 1991, 40 (8): 01371 doi: 10.7498/aps.40.1371
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In principle, four rypes of aluminum ions on the faujasite framework may be distinguished according to the next neighbour number (0,1,2,3) of aluminum appearing around their environment. The hydrogen ions associated with type-O aluminum ions are to be identified as "strong" acid, and those associated with types 1,2 and 3, as "weak" acid. In a dealuminization process, the "weak acid" aluminum ions (types 1,2 and 3) are removed preferably over the "strong acid" type-O. Based on first-order kinetics, the concentrations of all the four types aluminum ions upon dealuminization can be described in terms of the Monte-Carlo simulation of the dealuminization process of the faujasite. We conclude that the concentration of the strong acid center in dealuminization faujasites come up to its maximum around Si/Al 6.68. We also conclude that the more difference between dissolving rate constants for "strong" and "weak" aluminum ions the denser strong acid in dealuminization faujasite could be expected.
GENERAL

BOUND STATES OF THE DIRAC EQUATIONS WITH HULTHéN-TYPE POTENTIALS

HU SI-ZHU, SU RU-KENG
Acta Physica Sinica. 1991, 40 (8): 01201 doi: 10.7498/aps.40.1201
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The exact solutions of bound states of Dirac equation with one-dimensional vector and scalar Hulthén-type potential are obtained. For three-dimensional Hulthén-type potential, the S-wave exact solutions of Dirac equations are also presented provided the scalar potential is equal to the vector potential.

SOLITON EXITATION IN ONE-DIMENSIONAL QUANTUMb LATTICE GAS

CHEN CHUAN-YU
Acta Physica Sinica. 1991, 40 (8): 01207 doi: 10.7498/aps.40.1207
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In this paper, the non-linear properties of the nearest neighbor interaction between particles in one-dimensional quantum lattice gas are investigated, giving out the soliton theory of the model. The expressions of the solitons' energy and the effective soliton mass are also derived.

COHERENT STATES OF HYDROGEN ATOM

XU BO-WEI, ZENG QI
Acta Physica Sinica. 1991, 40 (8): 01212 doi: 10.7498/aps.40.1212
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From Kustannheimo-Stiefel transformation, the hygrogen problem in quantum mechanics can be transformed to that of a four dimensional isotropic harmonic oscillator with constrain. The coherent states are defined, for which the expectation values of the position and the momentum are shown to give the classical Kepler orbits. The uncertainty relations for the coherent states are discussed as well.

SCALAR QUANTUM ELECTRODYNAMICS WITH CHERN-SIMONS TERM IN (2+1) DIMENSIONS

NI GUANG-JIONG, XU JIAN-JUN
Acta Physica Sinica. 1991, 40 (8): 01217 doi: 10.7498/aps.40.1217
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By using a convenient perturbative expansion method, a scalar field φ in scalar QED with Chern-Simons term is quantized. Under the approximation oi one-loop diagram, we have derived the effective action for vector field Aμ and obtained two branches of (unstable) elementary excitation spectra. The coupling coefficient of Chern-Simons term is not affected by the quantization of φ field.

EXACT SOLUTION OF IRREVERSIBLE AGGREGATION EQUATION RELATED TO n-POLYMER

XUE YU, KONG LING-JIANG, CHEN GUANG-ZHI
Acta Physica Sinica. 1991, 40 (8): 01222 doi: 10.7498/aps.40.1222
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In this paper, we investigate the solution of the generlized Smoluchovski equation related to w-polymer. The exact solution of this equation with kernel K(i1,i2,…,in)=const and K(i1,i2,…,in)=sumfrom i=1 to n(il) il are discussed for monodisperse condition. we obtain their explict expressions of the size distrbution C(t), respectively. In addition, we discuss their long term behaviors.
NUCLEAR PHYSICS

EXPLANATIONS TO THE ANOMALOUSLY LARGE RADII OF NUCLEI NEAR THE NEUTRON DRIP LINE

REN ZHONG-ZHOU, XU GONG-OU
Acta Physica Sinica. 1991, 40 (8): 01229 doi: 10.7498/aps.40.1229
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Based on the analysis of the binding energy in light nuclei near the neutron drip line, the nuclei 6He,11Li ,14Be and 17B are considered as core-neutron-neutron three-body systems. The core-neutron and neutron-neutron interactions are assumed to be the weakly attractive exponential potentials. It has been shown that the three-body system can have a bound state even if any two constituents of the system cannot have a bound state. The anomalously large root-mean-square radii of 6He,11Li,14Be and 17B is due to the weak binding of the outer neutrons.

MONTE-CARLO STUDIES OF RADIATION DAMAGE INDUCED BY FUSION(I)——α-PARTICLES AT THE FIRST-WALL

HUO YU-KUN, WU XUAN-HONG, SHAO QI-YUN, CHEN JIAN-XIN, WU SHI-MING, PAN ZHENG-YING, GAO XING-HUA
Acta Physica Sinica. 1991, 40 (8): 01236 doi: 10.7498/aps.40.1236
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This paper investigates the spectra of fusion α-particle leaking out from the plasma boundary in a Tokamak fusion reactor, bombarding the first wall. The loss mechanisms of α-particle were studied, and the slowing down-diffusion equations describing the α-particle transport in plasma were set up. The contributions from banana-trapped particles, transit panicles and superbanana ripple trapped particles to the diffusion coefficient were included in the study. The equations were numerically solved for Tokamak reactors with typical parameters to obtain the required α-particle spectra. The physical significance of the results is discussed finally.
ATOMIC AND MOLECULAR PHYSICS

CALCULATIONS OF ENERGY LEVELS AND OSCILLATOR STRENGTHS FOR RuXIV ION

YUAN XIANG-JIN, DONG CHEN-ZHONG, YU GENG-SUN
Acta Physica Sinica. 1991, 40 (8): 01253 doi: 10.7498/aps.40.1253
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The energy levels of 4s24p, 4s4p2, 4s24d and 4p3 configurations and the electric, dipoie oscillator strengths of 4s24p-4s4p2, 4s24p-4s24d and 4s4p2-4p3 transitions ia RuXIV ion have been calculated by means of the configuration interaction (CI) theory and the parameter extrapolation method. The calculated energy levels of 4s24p, and 4s4p2 configurations are in good agreement with the observations, the energy levels of 4s24d and 4p3 configurations and the wavelengths and oscillator strengths of 4s24p-4s24d and 4s4p2-4p3 transitions are only theoretical values of prediction.

62D TRANSFER CROSS SECTION IN RUBIDIUM INDUCED IN COLLISIONS WITH GROUND STATE Rb ATOMS AND H2 MOLECULES

LIU ZI-DONG, SUN XIAN-FING, LI SEN-LIN, LIU ZHI-YUAN, ZENG XIAO-YUN
Acta Physica Sinica. 1991, 40 (8): 01259 doi: 10.7498/aps.40.1259
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Cross sections for 62D in Rb, induced by collisions with ground state Rb atoms and H2 molecules, have been measured using fluorescence methods. The results show that transfer cross sections for Rb(62D)-Rb(52S) are σfs = 67×10-14cm2, σtr = 4.3 ×10-14cm2 and transfer cross section for Rb(62D)-H2 are σfs*=0.44×10-14cm2tr*=0.01×10-14cm2.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

ION BERNSTEIN WAVE COUPLING FOR POLOIDAL ELECTROSTATIC ANTENNA IN TOKAMAK

SHEN XUE-MIN
Acta Physica Sinica. 1991, 40 (8): 01280 doi: 10.7498/aps.40.1280
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The coupling of Ion Bernstein Wave (IBW) excited at low-field side bv poloidal electrostatic antenna to plasma using uniform plasma model has been theoretically stydied. In order to more tally with the actual situation, the finiteness of antenna poloidal length and the nonzero poloidal wave number are considered. The computation of the coupling cord shows that the poloidal electrostatic antenna is able fo excited mostly IBW in plasma. The comparison between the poloidal electrostatic antenna and the conventional toroidal antenna for instrinsic spectral impedance, input impedance and wave energy fluxes is also made, from which it is concluded that the character of coupling IBW for both antenna is quite similar.

EXCITATION OF SHEAR ALFVEN WAVES IN KT-5B TOKAMAK

HAN SHEN-SHENG, ZHU SHI-YAO
Acta Physica Sinica. 1991, 40 (8): 01290 doi: 10.7498/aps.40.1290
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In this paper, the experimental results of Alfven wave excitation in KT-5B Tokamak are presented. The results show that there is a quite broad excitation region for shear Alfven waves, the wave energy coupling indicated by the antenna loadings increase as the plasma current and toroidal magnetic field increase. The electron temperature threshold effects and the preliminary evidence of the surface electrostatic wave are observed.
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