Vol. 33, No. 11 (1984)
1984, 33 (11): 1485-1494. doi: 10.7498/aps.33.1485
The current-voltage (I-V) characteristics of heavily doped n-GaAs metal-thin insulator (102?)-semiconductor barrier diodes can not be described by classical theory of metal-semiconductor contacts. It is necessary to modify the theory by assuming: (1) the electrons pass through the barrier of interface layer by tunnelling, resulting in transmission coefficient P; (2) at reverse bias, the effective barrier height alters due to the presence of interface layer and states and changes with variation of voltage; (3) at forward bias, the effects of interface layer are embodied in ideality factor n. The I-V and I-1/T expressions (table 1) derived from the modified theory are in good agreement with experimental results. The relationship between transmission coefficient and effective barrier height increasing is also discussed.
1984, 33 (11): 1495-1500. doi: 10.7498/aps.33.1495
The exact wave function of hydrogen atom near hard wall has been found in confo-cal elliptical coordinate system. Some propeties of the exeitons have been discussed.
1984, 33 (11): 1501-1511. doi: 10.7498/aps.33.1501
A method of calculating the theoretical strength of simple methls by application of the pseudopotential theory and the Born stability criteria is presented. The theoretical tensile and compreesive strength for six simple metals (Li, Na, K, Rb, Cs and Pb) at OK and under  uniaxial stress are evaluated.
1984, 33 (11): 1512-1519. doi: 10.7498/aps.33.1512
Based on accurate measurements of voltage and current between electrodes of a fast discharge XeCl laser, together with computer analyses, the kinetic impedance of gaseous mixture at high pressure of 3 to 8 atmospheres under discharge was obtained. The high impedance droped down to a fraction of ohm within several nanoseconds. The discharge peak currents and corresponding impedances of laser cavity at various charge voltages and gas pressures were studied. The results show that it is impractical and unimportant to match precisely the impedances of discharge plasma and of transmission line.
1984, 33 (11): 1520-1528. doi: 10.7498/aps.33.1520
The time-resolved degenerate four-wave mixing in a nearly degenerate quasi-two-level system is treated rigorously in this paper. It is shown that quantum beat effect exists in the time-resolved degenerate four-wave mixing. The behavior of the quantum beat are analysed and its possible applications are discussed.
1984, 33 (11): 1529-1537. doi: 10.7498/aps.33.1529
Described in detail in this paper is a useful method which can be used to study avalanches in electronegative gases and then to determine electron swarm parameters (ionization coefficient α, attachment coefficient η, and drift velocity v) including the number and distribution of primary electrons released from the cathode of a parallel electrode configuration by high energy laser pulses. The method has been used to study electron swarm parameters in mixtures of SF6 and CO2. Relations between the parameters (α/P, η/P and ν) and E/P (E=electric field, P=gas pressure) are given. A number above 108 of primary electrons has been obtained. The paper describes also the measurement system used in the study and improvements of the system that can be made.
OBSERVATION OF THERMAL EMISSION AND NON-THERMAL EMISSION FROM ELECTRON CYCLOTRON EMISSION IN CT-6B TOKAMAK PLASMA
1984, 33 (11): 1538-1545. doi: 10.7498/aps.33.1538
In this paper, the results of observation of electron cyclotron emission in CT-6B TOKAMAK device plasma is presented. The ECE was detected by using PME radiometer which can work at fundamental (35GHz) mixing or second harmonic (70GHz) mixing. It was obtained that when the device discharged under low runaway condition, the received signal emission at second harmonic mixing showed that it was the thermal emission associated with electron temperature; while under runaway condition, the receiving of emission at fundamental mixing showed that it was the nonthermal emission of the runaway electrons.
1984, 33 (11): 1546-1555. doi: 10.7498/aps.33.1546
The kinetic ballooning-mode eigenequation, which can be used to study the stability criterion in the second stability regime, is derived. It retains various most important kinetic effects. The corresponding form of this equation for circular tokamak is deduced to include the effects of the magnetic surface displacement and the poloidal magnetic field that become important in the second stability regime. The structures of the modes and the stability criteria for various configuration parameters are studied by using a numerical shooting code. Compared to the ideal MHD case, it is found that a new unstable branch of the mode exists in the second stability regime, having a very weak growth rate. In addition, there are several sorts of marginal stable modes, their behaviours have been studied to examine the effects of the magnetic shear and the poloidal magnetic fields.
1984, 33 (11): 1556-1562. doi: 10.7498/aps.33.1556
The behaviour of electrical conductivity and heat capacity of fast ionic conductor Rb4Cu16I7Cl13 has been studied in the temperature range -170-100℃. The results most likely show that this material undergoes second order phase transitions at about -26℃, -50℃ and -110℃ respectively.
The homopolar charge and heteropolar charge appeared in polarized ferroelectric ceramics result in pyroelectric relaxation effect. Three types of relaxation process given by the phenomenological theory are observed. Since energy is needed for the excitation of homopolar or heteropolar charge, at times long after the temperature change of the ceramic, the pyroelectric charges decay slowly as △Q(t)=(1+r±e(-(α±t)1/2)△Q∞.The theory is in good agreement with all experimental data for dozens of kinds of ceramic which have been measured.
1984, 33 (11): 1569-1580. doi: 10.7498/aps.33.1569
Assuming that the gluon possesses a non-zero effective mass μ, we derive an effective Hamiltonian for quarkonium by non-linear U(l) gauge field theories. For μ=0.2 GeV, 0.4 GeV and 0.6 GeV, we calculate the spectra for charmonium and upsilon, which are in good agreement with experiment. Finally, we discuss the effect of gluon mass on the spectra and potential.
STRUCTURAL ANALYSIS OF Li2O·14Nb2O5 BY COMBINED CONVERGENT-BEAM ELECTRON DIFFRACTION AND HIGH RESOLUTION ELECTRON MICROSCOPY
1984, 33 (11): 1581-1585. doi: 10.7498/aps.33.1581
Structurai analysis of Li2O·14Nb2O5 has been carried out by combined convergent-beam electron diffraction (CBED) and high resolution electron microscopy (HREM) in an analytical electron microscope with a point resolution of 0.4 nm. The space group C2/m is confirmed by CBED. HREM structure image shows that Li2O·14Nb2O5 is made up of 4×4 blocks of oxygen octahedrons The 3×3 channels within the 4×4 blocks and the metal atoms at the centres of the octahedrons which are 0.38 nm apart are clearly resolved. Combined CBED and HREM for structural analysis is an important development in electron crystallography.
1984, 33 (11): 1586-1588. doi: 10.7498/aps.33.1586
Dynamic extinction lines which occur in CBED patterns have been used to determine the presence of twofold screw axis and glide plane in Li2O·3Nb2O5. The space group is found to be P21/a.
In this paper, the transition probability distribution function including two parameters is derived using the whole Wigner function. The Jonscher's empirical formula of dielectric loss can be interpreted. This is a improvement on Ngai's theory of dielectric loss.
1984, 33 (11): 1593-1598. doi: 10.7498/aps.33.1593
This paper reports a degenerate four-wave mixing effect in Fe-doped LiNb03 crystal at low laser power (He-Ne laser, λ=6328?). The experimetal curves about intensity of conjugate wave vs. irradiate time at different pump power is given. The phase-compensated property of the conjugate wave was examined, and the phase distortion image was corrected by means of this property. The experimental results obtained agree with the theory.
1984, 33 (11): 1599-1604. doi: 10.7498/aps.33.1599
2-dimensioal Walsh transformation is realized by coherent optical system Composed of a single transform element. The element is made using a method of scanning-exposure. This optical system has higher efficiency and simple structure. The principle and experimental results are presented.
1984, 33 (11): 1605-1609. doi: 10.7498/aps.33.1605
We describe a novel method to enrich isotopes and isomers via magnetic deflection of optically polarized atomic beam. High electronic polarization with opposite signs for atoms of both isotopes respectively is achieved by selective optical pumping using lasers with different frequencies and polarizations and then the isotopes are enriched by deflecting the oppositely polarized isotopes along different directions by the inhomo-geneous magnetic field in the spin selective magnet. Separation selectivity and throughput are evaluated and the advantages, disadvantages and prospects of possible application of the present method are discussed in comparison with other existing methods. Experimental scheme with lithium or potassium is suggested.
1984, 33 (11): 1610-1618. doi: 10.7498/aps.33.1610
In this paper, based on the normalized electronic field and the eigenvalue equation for the four layer asymmetric structure, the approximate expressions of the normalized effective index and the radiation confirement factor were introduced, and the approximate equations for the near field and far field asymmetric Gaussian Profile were deduced.Using the above-mentioned analysis, the dynamic characteristics of the four layer asymmetric waveguide was investigated. From this, the analytic expressions of the injected carrier concentration profile and the gain profile were obtained, and the modal gain, the threshold current density, the optimal active layer thickness, and the optimal threshold current density can be calculated.The calculated results of a series of relation were discussed. We study further the structure parameter effect on the device.
1984, 33 (11): 1619-1623. doi: 10.7498/aps.33.1619
In the present paper, the cluster model and the charge self-consistent EHT method are used to study the chemisorptions of group VII elements on both Si (111) 1×1 and Ge(111)1×1 surfaces. The chemisorbed sites are determined by minimizing the total energy. For Cl, the absorption takes place on the atop sites for both Si (111) and Ge (111) surfaces. For I, the result shows that the threefold hollow sites of both surfaces are more preferable. For Br, both the atop and the threefold hollow sites seem to be possible on both surfaces. However, for Br/Si(lll)l×1 the atop site is more stable, whereas for Br/Ge (111)1×1 the threefold hollow site is more stable. Finally, the trend of the chemisorptions of the group VII atoms on the two surfaces are discussed and comparison with the recent SEXAFS results presented.
1984, 33 (11): 1624-1628. doi: 10.7498/aps.33.1624
The electronic absorption spectrum of the spherocrystal of bellingerite 3Cu(IO3)2·2H2O, was measured, two strong absorption bands appeared at 9140 cm-1 and 15250 cm-1. The low-symmetric crystal field splitting, which is as great as 6110cm-1, was observed for the first time. Resolving the absorption curve, we obtained 8 Gauss-type absorption peaks at 8590, 10690, 10870, 12190, 13500, 14510, 15330 and 16500 cm-1, respectively. By analyzing its EPR spectrum, we got g=2.141±0.004. The experimental results were discussed quantitatively using the ligand field theory and the radial wave function, of nonfree copper(II). The calculated values were in agreement with the experimental results. Thus the electronic structure of bellingerite crystal was interpreted comprehensively.