Search

Article

x

Vol. 41, No. 6 (1992)

1992-03-20
GENERAL
EVENT HORIZON AND TEMPERATURE OF SPHERICALLY CHARGED EVAPORATING BLACK HOLE
DAI XIAN-XIN, ZHAO ZHENG
1992, 41 (6): 869-872. doi: 10.7498/aps.41.869
Abstract +
A new method is suggested to determine the event horizon and the Howking temperature of a spherically charged evaporating black hole. The Klein-Gordon equation near the event horizon is solved.
ATOMIC AND MOLECULAR PHYSICS
ELECTRONIC STRUCTURE OF MOLECULAR RYDBERG STATES OF DIATOMIC MOLECULES WITH Si AS THEIR UNITED ATOM
SUN BIAO, LI JIA-MING
1992, 41 (6): 873-880. doi: 10.7498/aps.41.873
Abstract +
Based on the independent-particle-approximation (i.e. the multiple scattering self-consistent-field theory), we studied the electronic structures of Rydberg series of the diatomic molecules with Si as their united atom, such as N2, CO, BF, A1H, LiNa, "BeNe" and "MgHe". The principal quantum number of the first state of the Rydberg series is determined from the limit atom of the molecular elecronic configuration. The dynamics of the excited molecules has been elucidated. Our theoretical results prove to be in fair agreement with the existing experimental measurements, thus it can provide a reliable basis for future refined calculations such as the configuation interaction methods.
TRANSIENT IONIZATION PROBABILITY OF ATOMS UNDER THE ACTION OF NONMONOCHROM-ATIC LIGHT
YANG JIAN-HAO, LIU FU-SUI
1992, 41 (6): 881-884. doi: 10.7498/aps.41.881
Abstract +
This paper reconsiders the calculation methods of transition probability its quantum mechanics, and points out that under the action of non-monochromatic light with frequency width Aw, the ionization probability of atoms will seriously deviate from Fermi's Second Golden Rule within the initial interaction period △t≈1/△ω.
TOTAL CROSS SECTION MEASUREMENTS FOR ELECTRON SCATTERING ON N2 IN THE ENERGY RANGE 250-1400 eV
CHEN XIANG-JUN, FAN XIAO-WEI, XU KE-ZUN, YANG BING-XIN, XING SHI-LIN, WANG YONG-GANG, ZHANG FANG
1992, 41 (6): 885-889. doi: 10.7498/aps.41.885
Abstract +
A linear-transmission-type apparatus for measuring total cross sections of electron scattering by atoms and molecules has been set up. Measurements on N2 have been carried out for 250-1400eV electrons with an accuracy of 3.5%. The results have been compared with available experimental and theoretical values of the total cross section.
CLASSICAL AREA OF PHENOMENOLOGY
EFFECTS OF γ IRRADIATION ON LOSS CHARACTERISTICS OF SINGLE MODE OPTICAL FIBERS DOPED WITH RARE EARTH Er3+
HU KAI-SHENG, LI ZONG-XIANG, NING DING, LI HAO, ZHOU JIAN-PING, LIU WEI-MIN
1992, 41 (6): 890-897. doi: 10.7498/aps.41.890
Abstract +
This papers presents the effects of Co-60 gamma irradiation on the absorption loss of single mode optical fibers doped with rare earth Er3+. The parameters of optical fibers are measured, prior to irradiation and after irradiation and UV bleaching. It has been found that absorption loss in the wavelength range of 0.80-1.60μm is greatly lager than those of unirra-diated fibers. Its increase law of absorption loss is similar to that of β ray irradiation. This similarity can be explained by Compton's effect. The induced loss can be partly bleached by UV, resulting in a better effect than heat annealing. In order to improve radiation resistivity, the elements with smaller atomic number should be selected as dopants in both core and cladding of the fiber.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
EFFECT OF THE SMALL ACCESSARY LASER SPOTS ON THE HARMONIC EMISSION STIMULATED BY SELF-FOCUSING OF A 10-MICROMETER SCALE LASER SPOT
LIN ZUN-QI, ZHANG HUI-HUANG, HE XING-FA, LIN KANG-CHUN, WANG XIAO-QIN, ZHUANG YI-FEI, WANG LIU-SHUI, WEI XIAO-CHUN, LU QI-RONG, SHI A-YING, DAI MEI-LAN, TIAN LI, FAN GEN-LIANG, LI JIA-MING
1992, 41 (6): 898-909. doi: 10.7498/aps.41.898
Abstract +
A novel group of experiments has shown that single 10-micrometer-radius-scale laser spot is not able to produce the 90° side emitted three half harmonic efficiently in a preformed laser plasmas. However, with the help of one or two accessary laser spots with size similar to the main one, the side emitted three halfs can easily be built up when some position and angle conditions for the accessary spots are fulfilled. The origin of these phenomena have been analyzed in terms of the two plasmon decay theory and dynamic self-focusing model.
REDUCED FORM AND EIGENMODE SOLUTION OF GENERALIZED MHD EQUATIONS IN A CYLINDRICAL PLASMA
YANG WEI-HONG, HU XI-WEI
1992, 41 (6): 910-916. doi: 10.7498/aps.41.910
Abstract +
In this paper, the reduced form (four differential equations of the first order) of generalized MHD equations is obtained, only some approximations satisfied by the experimental condition of heating tokamak plasma are used. An analytical dispersion relation (eigenmode solution) for a homogeneous plasma cylinder is obtained. It is shown that Appert's theory is a limiting case of our theory.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
STUDIES ON ABSORPTION MECHANISM OF MICROWAVE ABSORBENT OF CONDUCTING POLYMERS
WAN MEI-XIANG
1992, 41 (6): 917-923. doi: 10.7498/aps.41.917
Abstract +
A physical model of conducting islands is proposed to explaine the characterizations of dielectric loss of conducting polymers caused by interface polarizability. According to this model, the behavior of the electric loss of conducting polymers caused by conducting islands depends on the dielectric constant and the conductivity of conducting islands itself, as well as its volume fraction occupied in the conducting polymers. The characterizations of dielectric loss of conducting polymers proposed by the model of conducting island are consistent with the observations obtained from experiments of microwave absorption of conducting polymers.
THE ROLE OF INTERNAL STRESS IN THE AMORPHIZATION PROCESS DURING MECHANICAL ALLOYING
MIAO WEI-FANG, LI GU-SONG, LI SHU-LING, WANG JING-TANG
1992, 41 (6): 924-928. doi: 10.7498/aps.41.924
Abstract +
The characteristics of amorphization process during mechanical alloying of the mixture of Ni and Zr powders have been studied by differential scanning calorimetry (DSC) and X-ray diffraction measurements. The role of internal stress in the amorphization process, together with the variation in internal stress are discussed.
ELECTRONIC STRUCTURE OF ATOM CLUSTER Fe4B
SHI SHUANG-HE, WANG XU-WEI, CHEN JIN-CHANG
1992, 41 (6): 929-936. doi: 10.7498/aps.41.929
Abstract +
Electronic structure of atom cluster Fe4B, taken as a tetrahedron, is calcu lated by using the self-consistent field Xα-scattered-wave method. The energy levels, contour maps and densities of states for the atom clusters Fe4 and Fe4B are analyzed and compared respectively, the effect of the B atoms on the electronic structure of atom cluster Fe4B is discussed, and some physical nature of amorphous alloy Fe80B20 is also discussed.
PHASE TRANSITION AND CRYSTAL STRUCTURE OF A NEW COMPOUND ——Sr2CaMoO6
LI ZHEN-WU, FU ZHENG-MIN, LI WEN-XIU
1992, 41 (6): 937-947. doi: 10.7498/aps.41.937
Abstract +
A new compound Sr2CaMoO6 has been synthesized by solid stare sintering. The phase transition of this compound was investigated by means of DTA, X-ray powder diffraction, precise measurement of lattice parameters and other methods. It is discovered that the compound has a displacive phase transition of the first order at (767±5)℃. The low temperaiure phase, or Sr2CaMoO6, belongs to orthorhombic system, with space group Pmm2, its lattice parameters at room temperature are:a = 8.1933?, b = 5.7611? and c=5.8410?, the measured density is Dm= 4.97g/cm3, and each unit cell contains two formula weight. The high temperature phase, β-Sr2CaMoO6, belongs to the cubic system, with space group Fm3m and the lattice parameter is α = 8.281? at 800℃; Z = 4. The calculated density is Dx= 4.76g/cm3.The crystal structures of α Sr2CaMoO6 and β-Sr2CaMoO6 was also determined by means of the X-ray polycrystal diffraction method. The character of the structure and the factors influencing phase transition temperature are discussed.
STUDY ON WETTING TRANSITION IN A MIXTURE FLUID(Ⅱ)——BINARY SYSTEM AT THREE PHASE COEXISTENCE
SONG YAN, HUANG ZU-QIA, DING E-JIAN
1992, 41 (6): 948-959. doi: 10.7498/aps.41.948
Abstract +
With Sullivan model as a start point, analysis study for the nature of wetting transition in binary system at three phase coexistence, the typical binary mixture, is conducted by means of trajectory expansion in dynamics approach, from which we modify and make supplements for our previous results.
STUDY ON WETTING TRANSITION IN A MIXTURE FLUID (Ⅲ)——BINARY SYSTEM AT FOUR PHASES COEXISTENCE
SONG YAN, HUANG ZU-QIA, DING E-JIAN
1992, 41 (6): 960-967. doi: 10.7498/aps.41.960
Abstract +
The wetting transition at four phases coexistence state, a special case of binary Sullivan systems, is studied. Much of its properties can be driven out by the study of two phases coexistence state of the binary system, and the wetting transition of the first order, as well as that of the second order are present.
STRUCTURE DETERMINATION OF HCOO-Cu(110) BY MULTIPLE SCATTERING CLUSTER METHOD
CHEN YI-BING, TANG JING-CHANG, FU SONG-BAO, JI HONG
1992, 41 (6): 968-976. doi: 10.7498/aps.41.968
Abstract +
Using the multiple scattering cluster method (MSC), we have calculated the oxygen K-edge NEXAFS spectra of formate molecule which is the intermediate in the catalytic decomposition of formic acid over Cu(110) surface. The calculation shows that the formate is adsorbed at the short-bridge site of Cu(110) surface, the bond-lengths LC-0 and LCu-o are 1.26±0.01? and 1.975±0.02? respectively, the O-C-O bond angle is in the range of 130°-134°. This result agrees with that of photoelectron diffraction, and demonstrates that the multiple scattering cluster method is an effective one for the surface structure determination.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
HEAVY ELECTRON METALS IN A NONZERO MAGNETIC FIELD
CHEN CHUN, LI ZHENG-ZHONG, XU WANG
1992, 41 (6): 977-984. doi: 10.7498/aps.41.977
Abstract +
The specific heat coefficient and magnetization of the heavy electron metals in a nonzero magnetic field are calculated by using the slave boson mean field theory. The results indicate that the heavy fermion feature of the system is depressed in the magnetic field. A theoretical explanation for anomalous volume magnetostriction of the heavy electron metals is also given in this paper.
STUDY OF DEFECTS IN LOW-DOSE P+ IMPLANTED AND RAPID THERMAL ANNEALED SILICON
LI XIAO-LEI, LU FANG, SUN HENG-HUI, HUANG QING-HONG
1992, 41 (6): 985-991. doi: 10.7498/aps.41.985
Abstract +
Defects charactistics of low-dose p+ implanted silicon after rapid thermal annealing (RTA) was studied. RTA at 600℃ can activate most implanted ions. The defects in samples after RTA below 800℃ are found mainly the ion-implantation induced damage defects. Dislocations are found in samples after RTA above 800℃. The ion-implantation damage defects and thermal stress during quenching step are responsible for the formation of dislocations. The concentration of defects in 1100℃RTA sample began to increace. Slip dislocations are induced by thermal stress in the wafer.
TOTAL CURRENT SPECTRA STUDIES ON ELECTRONIC STATES OF Si(100) SURFACE
WANG XIANG-DONG, HU JI-HUANG, GE YU-QING, DAI DAO-XUAN
1992, 41 (6): 992-998. doi: 10.7498/aps.41.992
Abstract +
Electronic states of Si(100)2×1 clean surface and Si(100)1×1-2H surface are studied with total current spectrometer. The occupied surface states are at 0.25, 8.4 and near 12 eV below thevalence band maximum, while the unoccupied surface states are at 0.7 eV above the valence band maximum. Two induced surface states of Si(100)1×1-2H are observed below the valence band maximum.
ANALYSIS OF THE HIGH Tc OXIDE SUPERCONDUCTORS FROM THE GOLDEN COORDINATES
JIN GUANG-HAI, ZHANG LI-YUAN
1992, 41 (6): 999-1004. doi: 10.7498/aps.41.999
Abstract +
In this paper, more than sixty high-Tc oxide superconductors are analysed again with Vil-lars coordinates. Moreover, we introduce two new coordinates, namely, the average electrone-gativity and chemical combination valence. It is found that the high-Tc oxide superconductors are distributed more concentratively in the diagram of these new coordinates.
MAGNETIC MOMENTS AND COERCIVE FORCE OF Tb1-xGdxFe2
ZHONG WEN-DING, LIU ZUN-XIAO
1992, 41 (6): 1005-1011. doi: 10.7498/aps.41.1005
Abstract +
The magnetization curves, the Curie temperature and the thermal dependence of the coercive force in the pseudobinary cubic Laves phase compounds Tb1-xGdxFe2(0≤x≤l) has been measured. The saturation magnetization decreases almost linearly from TbFe2 to GdFe2. The magnetic moment of the iron atoms is a constant(μFe -1.60±0.04μB) for the whole concentration range, while the moment of terbium atoms is smaller slightly than its free ion value of gJ = 9.0μB due to crystal-field effects. The coercive field has got two contributions: one cames from the intrinsic pinning of domain walls in the Peierls crystal pontential wells and the fluctuation of magnetocrystalline anisotropy at rare-earth site; this contribution is preponderant at low temperatures, decaying exponentially with increasing temperature. The other comes from the pinning of domain walls by the internal stresses, causing the appearance of free magnetic poles.
ELECTRO-OPTIC EFFECT IN PESO ACOUSTO-OPTIC MODULATOR
TAI REN-ZHONO, LU FU-YUN, YUAN SHU-ZHONG, GUAN XIN-AN, LI BING
1992, 41 (6): 1012-1018. doi: 10.7498/aps.41.1012
Abstract +
With the theory of one-dimensional approximation, combined with the boundary conditions, an inhomogeneous electric field is derived from the foundamental equations of pieozoelec-tric effect. This inhomogeneous electric field will lead to generation of "electric grating", and "high-order grating" can also appear owing to coupling between "electric grating" and "acoustic grating". Linear electro-optic effect in PESO modulator is helpful to the diffraction and modulation of the incident light beam. The experimental results verify our conclusions.
PHOTO-INDUCED ABSORPTION BAND IN QUASI-ONE-DIMENSIONAL HALOGEN-BRIDGED MIXED-VALENCE PLATINUM COMPLEXES
PENG JING-CUI
1992, 41 (6): 1019-1026. doi: 10.7498/aps.41.1019
Abstract +
Photo-induced absorption states in quasi-one-dimensional halogen-bridged mixed valence platinum complex is investigated. Based on the experimental data, a mechanism for photo-induced absorption is presented. Photo-induced absorption spectra both deformations of alternative and polaron induced for halogen ions are calculated. The comparison with experiments is made.
DEPENDENCE OF ISERS ON CONCENTRATION AND ADSORPTION ISOTHERM PROPERTY FOR SALICYLIC ACID IN SOLID-LIQUID SYSTEM
ZHENG HAI-CAI, GOU ZENG-GUANG, GUI MING, LI XIU-YING, MO YU-JUN
1992, 41 (6): 1027-1031. doi: 10.7498/aps.41.1027
Abstract +
The dependence of SERS intensity ISERS on the concentration c is studied experimentally for salicylic acid (SA) aqueous solution-Ag mirror system by measuring ISERS And the relation between ISERS and quantity of adsorbed molecules is also discussed. All the results suggest that the SERS technique indeed provides a efficient and high sensitive new method for studying adsorption isotherm property in solid-liquid system.
THE EFFECT OF DOPING CONCENTRATION ON BAND-GAP NARROWING OF p-TYPE GaAs
CHENG WEN-QIN, MEI XIAO-BING, LIU SHUANC, LIU YU-LONG, LI YONG-KANG, ZHOU JUN-MING
1992, 41 (6): 1032-1035. doi: 10.7498/aps.41.1032
Abstract +
The band-gap narrowing of p-type GaAs as a function of doping concentrafion has been investigated by photoluminescence spectroscopy on samples grown by molecular beam epitaxy on (110) semi-insulating GaAs. It was first found that the band-gap narrowing of p-type GaAs comes from the moving up of valence band, the location of dopant level (band) remains unchanged relative to conduction band, and the ionization energy decreases with the increase of doping concentration.
A STUDY OF SULFIDE TREATED InSb(111) SURFACES
DONG GUO-SHENG, LU CHUN-MING, LI ZHE-SHEN, WANG XUN
1992, 41 (6): 1036-1043. doi: 10.7498/aps.41.1036
Abstract +
Auger electron spectroscopy (AES), X-ray photoelectron spectroscop (XPS) and ultraviolet photoelectron spectroscopy (UPS) have been used to study the InSb(lll) surfaces treated with (NH4)O2Sx. It is found that after the sulfide treatment, the sample surfaces are covered by a thin overlayer of sulfide (8?), which prevents the sample surface from oxidization and carbon contamination in the air. XPS and UPS results show that S atoms bond to both Sb atoms and In atoms on the sample surfaces. Sb-S bonding peaks in the Sb3d spectra exhibit a core level shift of 1.9eV, the bonding of S to In atoms causes an In4d core level shift of 0.6-0.7eV. A thermal annealing at 350℃ gives rise to the decomposition of Sb-S bonding and the evaporation Sb atoms from the sample surfaces. In-S bonding can not be decomposed completely by annealing up to 500℃ and a small amount of S atoms remains on the sample surfaces in the form of indium sulfide.