Vol. 40, No. 10 (1991)
1991-05-20
GENERAL
1991, 40 (10): 1553-1561.
doi: 10.7498/aps.40.1553
Abstract +
Basing on the classical trajectory motion for an electron circling an atomic nucleus and averaging the motion over initial coordinate parameters of ellipse trajectories for the electron, we get a density distribution in space. This distribution is consistent with probability density of stationary state for hydrogen atom in the classical limit. This comparison shows that a wave function of hydrogen atom in stationary state does not describe an individual atom but an ensemble.
1991, 40 (10): 1562-1566.
doi: 10.7498/aps.40.1562
Abstract +
In this paper, we give the double wave function theory for systems of planar and spherical rotator, obtain rigorously the classical mechanical equations of motion for these two systems study the related problems in the ordinary quantum theory for these sfstems.
1991, 40 (10): 1567-1574.
doi: 10.7498/aps.40.1567
Abstract +
The spectral fluctuation properties of a quantum system are related closely to the dynamical symmetries of the system and its nonlinearity but not dependent upon number of the degrees of freedom. The energy spectrum of Helium atom is calculated, and by analysing the spectral fluctuations it is found that the residual one pair electron-electron interaction is not sufficient to change the dynamical symmetry of the nucleus-electron central field, eventhough the interaction is amplified artificially to a possible extent (as far as the dissociation of the system does not occur). It turns out that the contour plot of the potential intuitively gives the information about the symmetry of the system, indicates the degree of the symmetry breaking as well as the way how the symmetry is lost.
ATOMIC AND MOLECULAR PHYSICS
1991, 40 (10): 1575-1583.
doi: 10.7498/aps.40.1575
Abstract +
Steady-state resonance fluorescence spectrum from a three-level atom driven coherently by two intense optical fields and damped by a squeezed vacuum is obtained, which shows the dependence of the spectrum strongly on the squeezing of the vacuum field and the phase difference between the squeezed component of the vacuum field and the driven fields.
1991, 40 (10): 1584-1589.
doi: 10.7498/aps.40.1584
Abstract +
Previous studies on strong-field autoionization involving high-order ionization processes are mainly investigated for the cases of CW laser irradiations. This paper extends those studies to the cases of square laser pulses with arbitrary widths. Populations of the ground state and the line shapes of the autoionizing resonance are discussed. It is shown that strong-field autoionization and the high-order ionization processes are drastically affected not only by the intensities but also by the time of interaction between atoms and laser field.
1991, 40 (10): 1590-1594.
doi: 10.7498/aps.40.1590
Abstract +
The exponential variation method is applied to the charge exchange in H++ H collisions in the present paper. The angular distributions have been calculated practically for two incident energies, 60 and 125 keV. The present results show that the obvious improvement with respect to BIB approximation can be obtained by the exponential variation method.
1991, 40 (10): 1595-1600.
doi: 10.7498/aps.40.1595
Abstract +
The multiple-scattering expansion method proposed in Ref [6] has been applied to the calculations for the triple differential cross sections of the (e,2e) collisions of atomic hydrogen under the Ehrhardt geometric conditions. The present results are in good agreement with the experimental data.
CLASSICAL AREA OF PHENOMENOLOGY
1991, 40 (10): 1601-1606.
doi: 10.7498/aps.40.1601
Abstract +
Extraction of invariant moments used for pattern recognition is a subject in optics to be further studied. In this paper, an optical method utilizing a single holographic mask is presented for realizing two-dimensional geometric moment transform. The invariant moments of a group of English letters are extracted successfully, which indeed exhibit the invariant features under translating and rotating
1991, 40 (10): 1607-1612.
doi: 10.7498/aps.40.1607
Abstract +
In this paper, the behavior of SU(2) squeezing of the mixed-state in two-level atom are studied by means of the time-evolution operator method. We have obtained new results that the mixed-state atomic squeezing under interacting of the light field is deeper than the general pure-state atomic SU(2) squeezing. Furthermore, the squeezing value of the atom in pseudo-ground state is more greater than that in pseudo-excited state. The relation between the statistical probability of atomic level population and the squeezing is studied by numerical calculations.
1991, 40 (10): 1613-1623.
doi: 10.7498/aps.40.1613
Abstract +
A scheme is proposed, in which the pulse train of squeezed light is generated via forward four-wave mixing through a nonlinear medium with third-order polarizability, coherently pumped by a train of pulses of modelocked laser. One of the quadrature noise compoments of the squeezed light is measured with a balanced homodyne detector using a pulse train as the local oscillation. The theoretical results show that the fairly high-intensity output of squeezed light can be achieved, and the noise-power spectrum of the light is almost completely squeezed and exhibits the form of a train of pulses, but the shape of squeezed spectrum is reversed with respect to that of the pulse train of the input light.
1991, 40 (10): 1624-1631.
doi: 10.7498/aps.40.1624
Abstract +
The single-particle trajectories of relativistic electrons are studied in a magnetic field con-figuration consisting of a uniform axial guide field and a helical periodic wiggler field. The steady-state trajectories and the first order perturbed trajectories are analysed carefully. Based on the numerical simulations about the experiments which have been made at Shanghai Institute of Optics and Fine Mechanics, the effect of the betatron oscillations due to the transverse varing of wiggler field is first shown in the case that there is a axial guide field. In this case the betatron oscillations equations are drived. Its period and the relation between phase in X dirction and in Y dirction are obtioned. Further more, numerical simulations are made. The results of analytical calculation are in good agreement with the numerical simulations.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
1991, 40 (10): 1632-1637.
doi: 10.7498/aps.40.1632
Abstract +
The resonant absorption of light in cold plasma for linear density profile has been calculated analytically both for long and short scalelengths by calculating the reflectivity from the plasma and vaccum interface. The results in long scalelength case are in agreement with the well-known results but with a higher order in accuracy, and that in short scalelength case are consistent with numerical calculation.
1991, 40 (10): 1638-1641.
doi: 10.7498/aps.40.1638
Abstract +
In terms of Hasegawa-Wakatani equations,the nonlinear coupling of the electrostatic drift wave and the shear Alfven wave in magnetized plasmas has been investigated. The dipolar vortex solutions of the nonlinear equation system are obtained. These solutions belong to the intrinsic electromagnetic vortices, the corresponding magnetic field perturbations and the longitudinal current are continuous on the boundary of the vortex.
1991, 40 (10): 1642-1651.
doi: 10.7498/aps.40.1642
Abstract +
In this paper, an one and a half dimensional (1(1/2)-D, one space dimensionand two velocity dimension) plasma cloud-in-cell simulation code (CIC) has beendeveloped. It is used to study SRS in laser-plasma targets from the Shenguang-12# Nd-glass laser facility (λ=1.053μm,τ= 850ps IL= 3×1014—3×1015W/cm2). The results on the linear growth rates of the scattering electromagnetic waves and Lan-gmuir waves and nonlinear saturation are obtained in detail. Other results such as the time development of the electron distribution function and temperature and fraction of hot electron are also presented. In addition,temperature of thermal electron (1.4-2.5keV) in the underdense coronal plasma region is determined by spectrum analysis of SRS light, as well as contour figure for density distribution and averagedensity (0.12-0.14nc, n=1/4nc). These results agree with experiments.
1991, 40 (10): 1652-1659.
doi: 10.7498/aps.40.1652
Abstract +
The linear gyrokinetic equation near gyrofrequency in the presentation of three independent electric field components is derived by following the method of Chen and Tsai. This equation is suitable for investigation of radiofrequency heating in the inhomogeneous plasmas-The solutions of the equation for axisymmetric tokamaks is given.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1991, 40 (10): 1660-1665.
doi: 10.7498/aps.40.1660
Abstract +
By investigating orbital overlap population (OOP) resulting from the interaction between adatom and substrate Si atom, and total density of states of the cluster, it is found that Si(lll) 31/2×31/2- Sn has a half filled surface band which makesthe surface metallic. But for Si(lll) 31/2×31/2-Al, its bonding surface states are occupied fully with electrons and the antibonding surface states are empty, which makes the surface appear to be semiconducting. These calculation results are consistent with the experimental ones. A clear description on the interactions between Al, Sn and surface Si atom is also presented in this paper.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1991, 40 (10): 1666-1676.
doi: 10.7498/aps.40.1666
Abstract +
By means of the decomposition-decimation method based on the renormalization-group technique, we have studied the properties of electronic energy spectrum for the two-dimensional Fibonacci quasicrystals. It is found that the spectrum has a multifurcating structure which is very different from the monofurcating structure of one-dimensional Fibonacci quasicrystals. By using the four-fold symmetry of the Fibonacci quasilattice under study, we have reduced the Hamiltonian and then performed a numerical simulation, the results of which are consistent with the analytical ones.
1991, 40 (10): 1677-1682.
doi: 10.7498/aps.40.1677
Abstract +
The initial dynamics of photogenerated carriers in a-Si:H/a-SiNx:H multilayers has been investigated with time-resolved laser spectroscopy. The mechanisms of thermalization and recombination of these carriers are analysed. The results also reveal that the decay time cutoff, the mobility edge and the band-tail width vary non-monotonously with respect to nitrogen content with a turning point near x = 0.85, which may result from the changes of the internal electric field and the structure of multilayer with nitrogen content.
1991, 40 (10): 1683-1688.
doi: 10.7498/aps.40.1683
Abstract +
Basing on the density functional theory and LMTO-ASA band method, we study the properties of an average hybridization energy Ez of sp3 hydrid orbital, near the interface in semiconductor superlattice. It is shown that the Ez can be considered as a reference energy level for calculating the valence-band offsets △Ev at heterojunctions. The results indicate that the theo-retical values of the △Ev obtained with this method for several hererojunctions are in agreement with other theoretical and experimental results.
FLUX TRANSITION PROPERTIES OF RF-SQUID IN THE DIS-SIPATIVE MODE IN THE PRESENCE OF LARGE FLUCTUATION
1991, 40 (10): 1689-1693.
doi: 10.7498/aps.40.1689
Abstract +
In the presence of large thermal fluctuation, conditions that RF-SQUID in the dissipa-tive mode can be properly operated are analysed, the flux transition distribution densities are obtained, thus the mean value and the width of transition are derived. Finally we find that the-effective critical current of RF-SQUID loop is greatly reduced by large fluctuation and the transition width can be determined with a simple equation.
1991, 40 (10): 1694-1702.
doi: 10.7498/aps.40.1694
Abstract +
The magnetization curves of YBCO crystal prepared by melt-textured growth method were measured from 1.5K to 89K. Flux jumps were observed for H‖ c at 1.5K, 7K and 10K. Peak effects were observed for H‖ c in the temperature range of 15-83K. The anisotropies of magnetization curves and magnetic critical current are analysed in detail. The properties of connection between grains and the pinning mechanism are discussed.
1991, 40 (10): 1703-1711.
doi: 10.7498/aps.40.1703
Abstract +
The wave equation for nonlinear magnctostatic surface waves (MSSW) on ferromagnetic film is derived with perturbation theory under the condition of transverse magnetisation, and its solution is found. The nonlinear dispersion relation shows that a high wave power results in a reduction of frequency band of MSSW. The variations of group velocity dispersion and nonlinear frequency shift with the wave frequency and film thickness are also studied. The results show that the bright pulse envelope solitons can not exist in our case.
1991, 40 (10): 1712-1716.
doi: 10.7498/aps.40.1712
Abstract +
The coercive force, Hc and magnetostriction, λs, have been measured for nonequilibrium Fe1-xPdx alloys, with increasing x, Hc decreases but λs, increases. The decrease of Hc may be related to the decrease in the average anisotropy due to the reduction of crystal grain size. After annealing above 600K, Hc increases rapidly because of the precipitation of the ordered FePd phase.
1991, 40 (10): 1717-1722.
doi: 10.7498/aps.40.1717
Abstract +
A Z echo NMR pulse sequence is proposed for using in measurement of pure dipole or quadrupole spectrum. The Z echo NMR powder lineshape is not only independent of chemical shielding anisotropy but also, under strong radio-frequency field condition, independent of rf field inhomogeneity. This method is superior obviously to nutation NMR technique. The conclusions were analyzed theoretically and confirmed by experimental results.
1991, 40 (10): 1723-1728.
doi: 10.7498/aps.40.1723
Abstract +
The effect of dopant boron in bulk nickel on sputtering yield has been investigated by the Rutherford backscattering spectroscopy technique. It was shown that a decrease in sputter-ing yield with respect to pure nickel target can be described qualitatively by Painter and Ave-rill's model, but the decrease in our experiment appeared larger than that estimated by P-A model. The obvious effect of textured surface upon the reduction of sputtering of B-doped Ni target has been shown. It is conjectured that this reduction of net sputtering yield is very probably the result of a surface topography-binding energy combined effect.
