Vol. 40, No. 9 (1991)
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1991, 40 (9): 1377-1387. doi: 10.7498/aps.40.1377
We suggest a model of q-deformed rotating oscillator which possesses the symmetry of quantum group and point out that this model can be used to describe the vibrational and rotational structures of many microscopic systems. We construct the representation of q-oscilla or algebra and give energy values of q-oscillaor in this representation. It is shown that the q-oscillator spectra can be used to describe infrared spectra, Raman spectra and vibrational structure of electronic transitions of diatomic molecules.
1991, 40 (9): 1525-1532. doi: 10.7498/aps.40.1525
A new decoration method is proposed which can achieve an exact mapping between the quenched bond randomly diluted spin-1 Ising model on a regular lattice in the subspace: exp(K)cosh (J) =1 and a certain class of mixed-spin quenched site randomly diluted decorated-lattice problem. Using this mapping in conjunction with the annealed model solution for the decorated-lattice problem, we have obtained the approximate results for the quenched bond randomly diluted spin-1 Ising model on the honeycomb lattice. The critical temperature and the magnetization of the diluted system as functions of bond concentration are calculated in detail.
1991, 40 (9): 1533-1538. doi: 10.7498/aps.40.1533
Multiple Quantum (MQ) relaxation times of carbon-proton spin coupling system in chlo-roform(CHCl3), where the scalar relaxation mechanism of the second kind dominates the relaxation processes, were measured via their relevant MQ line widths in One Dimensional (ID) MQ Raman Magnetic Resonance(RMR). The cross correlation coefficient between carbon and proton spins and their coupling constants to the chlorine spin as well as their relative sign were deduced.
1991, 40 (9): 1388-1395. doi: 10.7498/aps.40.1388
The steepest descent perturbation theory is extended to the calculation of the energy and eigenfunction of the excited state of a quantum system. In case of the orthogonality of the trial function for the excited state to those for lower-energy state or ground state in the same symmetry class is preserved, the variational collapse to lower energy state can be avoided in this proposal. An iterative procedure is given for generating better eigenvalue and eigenfunction of the excited state without requiring an infinite summation over reference states as in conventional perturbation theory. This new perturbation method can be applied to calculate the excitation energy and wave function of excited states for any many-body quantum system to a high degree of accuracy without so much computational effort as in conventional method.
This paper introduces the generalized SU(2) coherent state of spin system. Its squee ing and antibunching, and generation are discussed. It is shown that under the contraction of group SU(2) to the harmonic-oscillator group, the generalized SU(2) coherent state transforms to the generalized Glauber coherent state, the related results of the contraction are also given.
SU(2) AND GLAUBER COHERENT STATES OF COOPER PAIRS IN SUPERCONDUCTOR——STUDIES OF THE QUANTUM CHARACTERS OF COOPER PAIRS AND JOSEPHSON SUPERFLUIDITY
1991, 40 (9): 1402-1410. doi: 10.7498/aps.40.1402
It is shown, using the quasi-spin operator, that the BCS superconducting ground-state wave function is the direct product of single Cooper-pair SU(2) coherent state wave functions, and in certain conditions, is SU(2) coherent state wave function of the Cooper-pair system. If two superconductors, both in BCS ground state, are coupled together, the coupled system is also in SU(2) coherent state. Under the contraction of group SU(2) to harmonic-oscillator group, the SU(2) coherent states contract to Glauber coherent states. The quantum fluctuations, distributions, and second correlations of Cooper pairs and Josephson superfluidity in the two cases are discussed.
1991, 40 (9): 1411-1416. doi: 10.7498/aps.40.1411
The fine structure of boron's Kα X-ray spectrum was investigated by means of a soft X-Ray Curved Crystal Spectrometer with high resolution. The Fourier selfdeconvolution technique, with a new type of dynamic-apodization function, was used to resolve intrinsically overlapped bands, increasing the resolving power and keeping good ratio of signal to noise. The results show the evidence of boron's (in B2O3) Kα X-ray spectrum fine structure with two peaks, at wavelength 67.657? and 67.536? respectively, which verify the theory of sp2 hybrid orbit of boron.
ATOMIC AND MOLECULAR PHYSICS
1991, 40 (9): 1417-1423. doi: 10.7498/aps.40.1417
By introducing dressed potential and Floquet partial wave expansion of the wave functions, the Schr?dinger equation is made separable. In case of strong laser field, the radial wave equations can be solved step by step approximately through the weak coupling method in which an appropriate perturbation term is selected. As an example, with a circularly polarized laser field, the scattering wave function, S-matrix and the cross section are obtained. Important conclusions are: multiphoton processes will appear under strong laser field; m-th multi-photon processes must be connected with a corresponding class of resonance lines with energy near m?w. The formula of line intensity is also obtained.
CLASSICAL AREA OF PHENOMENOLOGY
DIFFRACTION AND INTERFERENCE EFFECT OF DOUBLE GRATINGS WITH A ROTATION-ANGLE UNDER PARTIALLY COHERENT ILLUMINATION
1991, 40 (9): 1424-1424. doi: 10.7498/aps.40.1424
In this paper, the diffraction and interference effect of double gratings with a rotation-angle under partially coherent illumination is studied, it is a generalization of Lau- Talbo-Moire effect. A general analytic expression of light intensity distribution at the observation plane is obtained by means of ambiguity function method. Some special cases are discussed and verified by experiments.
A way is presented with which the optical field states exhibiting much deeper squeezing can be achieved through a simple superposition of the vacuum and the squeezed states with smaller squeezing. The enhancement effect of squeezing and the antibunching effect exhibiting in the superposition states depend on the average photon number of the squeezed states and, are very remarkable for the field exhibiting much smaller squeezing.
1991, 40 (9): 1443-1447. doi: 10.7498/aps.40.1443
This paper presents the diffraction efficiency of two-wave mixing in Fe-LiNbO3 (up to-76%) through low frequency modulating one light beam, which is twice greater than the diffraction efficiency (30%) without modulation. Our theoretical analysis of moving grating is. used to explain the experimental results.
1991, 40 (9): 1448-1455. doi: 10.7498/aps.40.1448
Tunable VUV laser (ω4=2ω1+ω3) in the range of 124.80-125.06nm is gene-rated by four-wave sum mixing in Hg vapor with Ar as buffer gas, when one of the pump beams (ω1) is tuned exactly to 61S0—71S0 two-photon resonance and another pump beam (ω3) on the blue side of 71S0—91P1 transition. The experimental results are analysed with the small signal four-wave sum mixing theory. The factors affecting the best phase matching condition and the methods to expand the tunable range of VUV output in the weak pump case are discussed.
1991, 40 (9): 1456-1459. doi: 10.7498/aps.40.1456
The dynamic processes of ultrashort Kerr effect in CS2 have been studied by laser frequency domain method. It is found that there are two kinds of relaxation processes which are lps and 0.lps respectively. The physical mechanism is discussed in this paper.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1991, 40 (9): 1460-1467. doi: 10.7498/aps.40.1460
This paper reports the study of the intensity ratio method for measuring anomalous scattering factor, by means of which the anomalous scattering factor of Ga atoms in GaAs near K absorption edge was well determined. This paper also discusses and deals with the problems that may appear when this method is used.
1991, 40 (9): 1468-1473. doi: 10.7498/aps.40.1468
Fe20Al80 amorphous powders were prepared by ball milling through 180 hours. X-ray diffraction and transmission electron microscope experiments indicate the powder sample is amorphous and also show the average particle size and crystallization products. The paramagne-tism and crystallinity of amorphous material are determined by M?ssbauer effect measurements.
1991, 40 (9): 1474-1484. doi: 10.7498/aps.40.1474
Starting from the Hamiltonian of Jahn-Teller effects and electron-electron correlation, we have studied the influence of electron correlation on the structural phase transitions due to the Jahn-Teller effects. By choosing different values of the parameters in the Hamiltonian, we concluded that there exist three possibilities as follows: (1) The system posesses only one structural phase transition, which corresponds to the symmetry breaking. (2) The system has a symmetry-breaking phase transition at high temperature, while the broken symmetry will be revived by decreasing the temperature. (3) The system has no phase transition throughout the whole temperature range.
Kinetics of second phase Ba6Ti17O40 formation in the mixture of BaTiO3 and excess TiO2 were studied by high-temperature X-ray diffraction method. The reaction curves were obtained at various temperatures for the formation of Ti-rich phase Ba6Ti17O40, and the reaction rate constant K and the activation energy Q were calculated. Finally, the mechanism of second phase Ba6Ti17O40 formation and the effect of excess TiO2 are discussed.
1991, 40 (9): 1492-1500. doi: 10.7498/aps.40.1492
The wetting transition in binary Sullivan systems at two phase coexistence has been studied analytically. The results show that the order of the wetting transition is sensitively dependent on the details of the model. The present method can be used conveniently to study the wetting transition in binary Sullivan systems at multiphase coexistence.
XPS STUDY OF Cu PRECIPITATIONS AT THE SURFACE OF CRYSTALLINE Cu-Zr ALLOYS AFTER ANNEALING IN HYDROGEN
1991, 40 (9): 1501-1504. doi: 10.7498/aps.40.1501
Crystalline Cu-Zr alloys of various composition were annealed (200-400℃) in ultra-high vacuum and in hydrogen, and their surface composition was analyzed by X-ray photoelec-tron spectroscopy. Contrary to the mostly observed oxygen induced surface segregation of Zr we found strong Cu segregation after annealing Cu-rich sample in hydrogen atmosphere. Scanning electron micrographs show surface Cu precipitates, apparently formed due to the effect of the heat of chemisorption of hydrogen on Cu.
1991, 40 (9): 1505-1513. doi: 10.7498/aps.40.1505
On the basis of the diagnostics about the axial distribution of plasma electron temperature and electron density in an axial flow RF PCVD reactor by using electrical probe, a model for two-dimension fluid kinetics concerned with major PCVD parameters is proposed. A kinetic analysis about how deposition profiles are influenced by major PCVD parameters is presented by means of the analysis of plasma parameters. The model has been applied to study the deposition process of SnO2 films obtained from a gases mixture of SnCl4 and O2. The theoretical calculation are in good agreement with the experiments of deposition.
1991, 40 (9): 1514-1519. doi: 10.7498/aps.40.1514
The compositional depth profile of GexSi1-x/Si strained layer superlattice has been obtained by AES combined with argon ion sputtering, which indicates the concentrations of Ge and Si vary with depth periodically. The secondary electron image shows some periodic pattern consisting of alternate bright and dark bands around the center of the sputtered crater. The characteristics of Auger depth profile as a method for superlattice structure analysis, as well as its limitations, are discussed.
1991, 40 (9): 1520-1524. doi: 10.7498/aps.40.1520
The microstructure and properties of ion plated titanium nitride film can be improved by adding rare earth element yttrium. Y-modified titanium nitride (Ti(Y)N) film exhibits an excellent corrosion resistance and binding strength to the substrate of A3 steel. The microstructure characteristics of Ti(Y)N/A3 system have been investigated by X-ray diffraction, ion probe mass analysis and cross section transmission electron microscopy. The results show that yttrium is enriched at the interface of Ti(Y)N/A3 system and the modification of Y at the interface leads to a very good metallurgical transition band from the substrate to the film and the preferential orientation along close-packed TiN(lll) crystal plane, which may be the major reasons for the improvement of the properties of the Ti(Y)N film.
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
1991, 40 (9): 1539-1545. doi: 10.7498/aps.40.1539
By the method of remelting and recrystalization, the GaAs single crystal doped with Te grew from the floating melt in microgravity environment in space. The GaAs single crystal broke in the middle, showing that the long floating melt was not stable. No impurity striations were found in the middle part of the crystal, which indicated that buoyancy-driven convec-ion disappeared, but they were observed on he outer layer of the crystal, showing that there existed Marangoni convection. The control of segregation mechanism of impurities in the short melting zone and the volatilization of Te impurity from the melt resulted in the decrease of impurity contents and nonuniform macroscopic distribution of impurities in the crystal. The dislocation defect in the crystal was due to the thermal stress caused during rapid growth and the collapse of vacancy clusters at the side of interface seed crystal.
GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS
1991, 40 (9): 1546-1552. doi: 10.7498/aps.40.1546
A universal method for determining if there exists an event horizon in a stationary space-time and showing its location is given in this paper. It is useful for studying Hawking effect in every static or stationary space-time.