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Vol. 36, No. 6 (1987)

1987-03-20
CONTENT
THE PHOTODISSOCIATION DYNAMICS OF CYANAMIDE AT 193 nm
I. A. MCLAREN, J. B. HALPERN, W. M. JACKSON, XIE XIAO-XIANG
1987, 36 (6): 691-697. doi: 10.7498/aps.36.691
Abstract +
The photodissociation dynamics of cyanamide have been investigated. Laser-induced fluorescence (LIF) was used to study the formation of CN(X2∑+) radical in the photodissociation at. 193 nm. A very weak LIF signal from the CN(X) radical was detected at a laser intensity of 0.35 mJ/pulse and the rotational temperature is 1590±90 K. When the laser intensity is high, the LIF signal increased obviously and the population in the ν"= 2 level was observed. The absorption cross section we measured at 193 nm is less than 2.4±10-19cm2 at a temperature of 50℃. A secondary photolysis mechanism can be used to explain the experimental results.
PROPERTIES OF κ-PHOTON UNITARY OPERATOR
GUO GUANG-CAN, WU CHANG-HONG
1987, 36 (6): 698-704. doi: 10.7498/aps.36.698
Abstract +
We have studied the properties of k-photon unitary operator Sk(z), including the change in properties of phase space under the action of Sk(z) and properties of coherent state and vacuum state which underwent the action of high order nonlinear processes. The results show that the light field should have some new non-classical properties which is unknown as yet.
THE PROPERTIES OF AMORPHOUS GdTbFe FILM FOR MAGNETO-OPTICAL RECORDING
CAI HENG, WANG YIN-JUN, TANG QIAN, YANG KE-MIN, SHEN JIAN-XIANG, ZHANG XU-XIN
1987, 36 (6): 705-711. doi: 10.7498/aps.36.705
Abstract +
Prepared by using bias magnetron-sputtering, the deposited GdTbFe films possess the suitable parameters for magneto-optical recording. The perpendicular anisotropy constant Ku increases with the increase of bias voltage. By means of the plots from both Johnson-Mehl-Avrami equation and Kissinger equation, the parameters of crystallization kinetics, △E = 2.0eV and n = 1 have been determined for amorphouss Gd27Tb10Fe63 film. The crystallization temperature and active energy AE of the amorphous Gd27Tb10Fe63 film are greater than the binary system, GdCo, GdFe, for example. The isothermal annealing of amorphous Gd27Tb10Fe63 film at various temperature shows that it has a good thermal stability which is required for magneto-opticai recording application.
VACUUM ULTRAVIOLET SPECTRA OF CT-6B TOKAMAK PLASMA
HUANG MAO, WANG WEN-SHU, LI ZAN-LIANG
1987, 36 (6): 712-716. doi: 10.7498/aps.36.712
Abstract +
A spectrographic survey of the impurity lines was made on the CT-6B Tokamak with I metre grazing incidence spectrograph. The observed wavelength ranges were from 1580 to 550 ? and from 460 to 43 ?, using 300 lines/mm and 1200 lines/mm gratings respecrively. The survey revealed that the main impurities in CT-6B Tokamak plasma are Mo for high Z impurities and C, N, O for low Z impurities. There are a large number of OV and OVI lines with intense emission. We also observed MoVIIl resonance lines 234.314 ?, 235.510 ? and 237.215 ?. The shortest observed wavelengths are the second order of OVII lines 21.6020 ? and 21804 ?. The first order of these two lines situate beyond the film and can not be recorded. According tc the features of the spectra and the ionization potentials of OV, OVI as well as MoVII, the average electron temperature for CT-6B Tokamak is estimated to be about 140 eV. Oxygen is the main impurity in CT-6B Tokamak, and its lines emission is the main portion of energy loss in CT-6B Tokamak. Lines of the main components of the vacuum-vessel material such as Fe, Cr, Ni and Ti have not been found.
STUDY ON HEAT TRANSPORT IN TOKAMAK PLASMA FROM SOFT X-RAY SAWTOOTH OSCILLATION
YANG XUAN-ZONG, QI XIA-ZHI, WANG LONG
1987, 36 (6): 717-724. doi: 10.7498/aps.36.717
Abstract +
Soft X-ray emission and its fluctuation in CT-6B tokamak are detected by using a Au(Si) surface barrier detectors array. The empirical scaling law for soft X-ray sawtooth oscillation in the center of plasma during internal disruption period is given in this paper. The electron thermal transport phenomena, such as electron heating rate, electron energy balance, electron energy confinement time, current density distribution, and electron temperature in the center of plasma during internal disruption are studied from soft X-ray sawtooth oscillation observations.
TRANSMISSION PROBABILITY IN ONE-DIMENSIONAL NORMAL-METAL MULTICHANNEL STRUCTURE
CHEN GENG-HUA, ZHAO ZHONG-XIAN
1987, 36 (6): 725-735. doi: 10.7498/aps.36.725
Abstract +
In this paper, the strictly one-dimensional normal metal multichannel structures are considered. We point out that the structures in multichannel cases can also be treated with an improved form of Büttiker's method, which was originally used for two channel cases. A formula for multichannel transmission coefficient is presented. As a simple example, the numerical results for three branches are given, which show the application of the formula and illustrate the transmission probability resonances in such structures.
D3d SYMMETRIC LOCAL SPECTRAL DENSITIES AND THE ELECTRONIC STRUCTURES OF SUBSTITUTIONAL PAIRS IN Si
GU YI-MING, REN SHANG-YUAN
1987, 36 (6): 736-744. doi: 10.7498/aps.36.736
Abstract +
By using the irreducible representation basis functions of the point group whose symmetry is lower than Td, a decomposition of the total density of states is considered. The calculation-results are obtained for the D3d point group in Si. Combining with the Koster-Slater Green's function method and on site approximation, the calculation results are used to analyse the electronic structures of the divacancy and the chalcogenide paris (S20, Se20, Te20) in Si. Some interesting results are obtained as follows; The distribution of the local spectral densities closely related to the deep states in forbidden band is similar for point and pair defects. Under the expellant action caused by the local spectral density, the symmetrical A10s (chalcogenide pairs) and Eg, (divacancy) states are higher than the antisymmetrical A2us (chalcogenide pairs) and Eu, (divacancy) states. The distribution of the deep state wavefuctions in Bloch space is also, similar for point and pair defects.
STUDY OF THE DEFECTS IN SILICON PRODUCED BY HIGH TEMPERATURE ELECTRON IRRADIATION
LU FANG, SUN HENG-HUI, HUANG YUN, SHENG CHI, ZHANG ZENG-GUANG, WANG LIANG
1987, 36 (6): 745-751. doi: 10.7498/aps.36.745
Abstract +
A study of defects in silicon produced by hightemperature electron irradiation was carried out. It was found that the introduction rate of defect increased with the temperature at which the samples were irradiated by electron. After the temperature reached an "extreme" value Tm, the introduction rate of defect began to decrease. The Tm value was related to the annealing activation energy of defect. It was also found that the density of E3 (Ec-0.36 eV) defects greatly increased in hightemperature electron irradiation. When electron irradiation was carried out at 330℃, the density of E3 defects was about 6 times as large as that at room temperature. The possible structure of the E3 defect is multivacancy-oxygen complex.
A METHOD TO DETERMINE THE SPECIFIC CONTACT RESISTANCE OF METAL-SEMICONDUCTOR CONTACT——CIRCULAR RING STRUCTURE METHOD
ZHU DE-GUANG, WU DING-FEN
1987, 36 (6): 752-759. doi: 10.7498/aps.36.752
Abstract +
In this paper, a method to determine the specific contact resistance of metal-semiconductor contact——circular ring structure method is presented. The equations for specific contact resistance which are used to both the definite thick and semiinfinite samples were derived. Some measurements and calculations have been carried out, the results are in good agreement with chose of methods published in the literature.
GENERAL CONVERSATION LAWS IN EINSTEIN-CARTAN THEORY
DUAN YI-SHI, LIU JI -CHENG, DONG XUE-GENG
1987, 36 (6): 760-768. doi: 10.7498/aps.36.760
Abstract +
Using Noether's theorem, the conversation laws for general Lagrangian in Einstein-Cartan theory are derived. The general covariant energy-momentum conversation law for general Lagrangian including torsion is obtained from general displacement transformation xμ'=xμ+edμba. It is shown that in our general case the superpotential must be existed. This result is the natural extension of the theory in references [1] , [2].
BRIEF REPORT
HEXAGONAL METASTABLE PHASE IN Fe-12.6 at%B ALLOY PRODUCED BY SPLAT-MELTING
QIN ZHI-CHENG, WANG WEN-KUI, HE SHOU-AN
1987, 36 (6): 769-772. doi: 10.7498/aps.36.769
Abstract +
The lattice structure of a new metastable phase in Fe-12.6 at %B alloy produced by splat-melting has been determined by X-ray diffraction and electron diffraction. All of the diffraction pattern can be uniquely indexed in terms of the hexagonal lattice with the lattice parameters a=5.501 ?, c= 7.213 ? and c/a = 1.311.
ATOMIC COLLISION PROCESSES WITH HIGH ENERGY ATOMIC IONS
TONG XIAO-MIN, LI JIA-MING
1987, 36 (6): 773-777. doi: 10.7498/aps.36.773
Abstract +
Based on the first Born approximation, we develope a simple theoretical method to calculate the cross sections of various high energy atomic collision processes. For the 4 kinds of incident particles (H+, e-, H, H-) our theoretical cross sections for the target-atom excitation process Na(3s-3p) are consistent with the recent absolute experimental measurement.
CALCULATION OF THE SPECTRA FOR TOPPONIUM WITH A NONZERO GLUON EFFECTIVE MASS
XIE FENG-XIAN
1987, 36 (6): 778-784. doi: 10.7498/aps.36.778
Abstract +
In this paper, we calculate the spectra for topponium, using a quarkoniun potential with a nonzero gluon effective mass.
THEORETICAL EXPLANTION OF THE CHANGE OF LOW TEMPERATURE SPECIFIC HEAT OF HEAVY-FERMION COMPOUND CeAl3 WITH PRESSURE
FENG SHI-PING
1987, 36 (6): 785-789. doi: 10.7498/aps.36.785
Abstract +
We use periodic Anderson Model Hamiltonian to explain the change of the low-temperature-specific heat of heavy-fermion compound CeAl3 in low pressure range.
LANDAU'S FERMI LIQUID THEORY OF HEAVY-FERMION SUPERCONDUCTING SYSTEMS
FENG SHI-PING
1987, 36 (6): 790-795. doi: 10.7498/aps.36.790
Abstract +
We have established approximately a relation between the parameters of periodic Anderson-model hamiltonian and the Landau's phenomenalogical parameters, and applied it to heavy-fermiqn superconducting systems. Calculation results are in agreement with experiment results-qualitatively. We conclude that superconducting systems induced by heavy-fermion liquid interaction are P-wave type ones.
EFFECT OF DIAGONAL DISORDER ON SUPERCONDUCTIVITY IN THE TRIPLET BIPOLARONIC SYSTEM
ZHANG LI-YUAN, LI YAN-MIN
1987, 36 (6): 796-800. doi: 10.7498/aps.36.796
Abstract +
The effect of diagonal disorder on superconductivity of the triplet bipolaronic system with a two-delta random site energy distribution is analysed in the framework of the mean-field approximation. It is found that this kind of disorder strongly affects superconductivity of the system. When the triplet bipolaron concentration is near 1/2, the transition temperature decreased seriously; while when the concentration is small, the normal random site energy can not impede the occurence of superconductivity completely. This results from the tunneling motion of triplet bipolarons. It is therefore expected that superconductivity may appear in some amorphous semiconductors with low bipolaron concentration.
TRANSMISSION PROBABILITY AND RESONANCES IN NON-SYMMETRIC ONE-DIMENSIONAL MICROSCOPIC NORMAL METAL RING
CHEN GENG-HUA, ZHAO ZHONG-XIAN
1987, 36 (6): 801-806. doi: 10.7498/aps.36.801
Abstract +
Basing on the method of Büttiker et al., the analytic expressions of low temperature transmission amplitude for two kinds of normal metal ring with non-symmetric branches are obtained. The interesting resonances in the transmission probability for such structures are discussed. The results derived from the general analytic expression in two special limits are similar to those in reference [11] . In addition, we point out that there are some mistakes in equations (4.24) and (4.39) of reference [11] .
THE STEP-RELATED ELECTRONIC STATES ON THE VICINAL SURFACES OF Si(001)
W. RANKE, CHEN XIAO-HUA, XU YA-BO, LI HAI-YANG, JI ZHEN-GUO
1987, 36 (6): 807-813. doi: 10.7498/aps.36.807
Abstract +
Angle-resolved ultraviolet photoelectron spectroscopy has been used to investigate the step-related electronic states on the vicinal surfaces of Si(00l). Such states have been found at 0.5-0.6 eV below EF at Γ point (K = 0) for vicinal surfaces with steps along 〈100〉 or 〈110〉. The dispersion of these states is smaller than that of the (001) surface states.
SYMMETRY AVERAGE POINTS IN THE BRILLOUIN ZONE
XUE FANG-SHI
1987, 36 (6): 814-818. doi: 10.7498/aps.36.814
Abstract +
We present sets of symmetry average points in the Brillouin zone from which the average over the Brillouin zone of a periodic function of wave vector can be determined easily. The calculation accuracy is comparable to that of special points, but the calculation labour is reduced considerably. The symmetry average points for crystals with cubic and hexagonal Bravais lattices are given and the calculation accuracy is illustrated numerically through an real example.
THE LIFETIME MEASUREMENT OF THE 28Si COMPOUND STATE OF 13.095 MeV BY THE BLOCKING EFFECT
JIN WEI-GUO, ZHAO GUO-QING, SHAO QI-YUN, REN YUE-HUA, WU XIANG-JIAN, ZHOU ZHU-YING
1987, 36 (6): 819-822. doi: 10.7498/aps.36.819
Abstract +
The methods for treating the Al single crystals have been improved and high quality crystals are obtained. The experiment of radiation damage in the Al crystals is carried out and the lifetime of the 28Si compound state of 13.095 MeV, excited by the 27Al(p,a)24 Mg resonant reaction at Ep = 1565keV, is measured. The lifetime, τ = 16.3±2.4 as, is deduced by comparison with the calibration curves calculated with Monte Carlo model and "analytical" methods. The corresponding energy level widtk, Γ = 40±6eV, is in good agreement with that reported in the literature.
THE MEASUREMENT OF REFRACTIVE INDICES AND DENSITY OF RARE-EARTH PENTAPHOSPHATE CRYSTALS
LI BAO-XIANG
1987, 36 (6): 823-827. doi: 10.7498/aps.36.823
Abstract +
In this work, the refractive indices, density, molar volume and molar refractive degree of LnP5O14 crystals have been measured. The influence of wavelength and temperature on optical properties was also studied and some regular results were obtained. These results indicated that the properties of rare-earth compounds depend not only on the nature of rare-earth ion itself but also on the conditions of environment.