Vol. 34, No. 6 (1985)
1985, 34 (6): 709-714. doi: 10.7498/aps.34.709
For the practical calculation of multiphonon transition probabilities, we have introduced the concept of multi-frequency models, whereby the phonon frequency spectrum is divided into equal intervals of ω0 and the corresponding phonon energies are approximated by integral multiples of hω0. The present paper investigates the method of steepest descent as applied to such calculations with multi-frequency madels. It is fo-and the that the sum of the contributions from the infinite relevant saddle points gives a series of δ-functions situated at phonon transition energies equal to integral multiples of hω0. This singular structure reflects the discrete structure artificially introduced by the multi-frequency model. Averaging the result with respect to phonon transition energy over hω0 just serves to smooth out the artificially introduced siugular structure; this smoothed result is directly given by the contribution from a single saddle point.
1985, 34 (6): 715-724. doi: 10.7498/aps.34.715
After annealing treatment in dry oxygen, the variations of the surface charges, the interface state densities and the state density distributions in the band gap, of both Au-doped and undoped Si-SiO2 interfaces were studied experimently. The annealing behavior of the negative electric effects of gold was also investigated. Furthermore, this paper presents the compared results of the electric properties of the Si-SiO2 interfaces (including both Au-doped and undoped interfaces) formed by thermo-oxidizing silicon in dry oxygen at various temperatures and gone through annealing in dry oxygen at the same temperatures.
STUDY OF STIMULATED PHOTON ECHO IN DEGENERATE TWO-LEVEL SYSTEM GENERAL THEARY AND RELAXATION INDUCED STIMULATED PHOTON ECHO
1985, 34 (6): 725-736. doi: 10.7498/aps.34.725
The stimulated photon echo in degenerate two-level system has been studied. The stimulated photon echo signal for different polarization arrangement of incident lights was obtained basing on the third-order perturbation theory, where, the density matrix was expanded in an irreducible spherical-tensor operator. The characteristics of stimulated photon echo were discussed. Taking ja = jb = 1/2 system as example, we have also studied the relaxation induced stimulated photon echo, where, the polarization arrangement of the three incident pulses is σ+→σ+→σ-.
1985, 34 (6): 737-744. doi: 10.7498/aps.34.737
The effect of the stochastic field on the degenerate four-wave mixing signal intensity hag been studied basing on the phase-diffusion model. It is shown that the ratio of the correlation time of the laser source to the relaxation time of the induced grating plays an important role. The effect of the stochastic property of laser source on the linewidth of mixing signal has also been discussed.
1985, 34 (6): 745-751. doi: 10.7498/aps.34.745
Three orders of Stokes and six orders of anti-Stokes in several tenth atm H2 SRS are obtained simultaneously. The stimulated Raman process (SRP) and four-wave parametric process in SRS energy transfer are investigated in this pper. The off-axis Stokes ring and on-axis anti-Stokes spot are studied experimentally in more detail here, and the experimental results are discussed by means of parametric and nonparametric-theory of nonlinear optics.
1985, 34 (6): 752-759. doi: 10.7498/aps.34.752
The phase-adjusted focusing laser accelerator requires a laser field with special polarized distribution—a radial polarization. The theoretical work shows, by properlytransforming the TEM00 mode, such a laser field can be obtained and propagate stably in the free space. The experimental result agrees with the theoretical analysis.
SPACE-INVARIANT AND ROTATION-INVARIANT IN A GIVEN ANGLE RANGE PATTERN RECOGNITION AND THEIR FILTER DESIGN
1985, 34 (6): 760-765. doi: 10.7498/aps.34.760
Hsu et al have proposed a method of filter design for space-invariant and rotation-invariant digital pattern recognition in terms of circular harmonic expansion. Based on their method, we suggest a new filter design for space-invariant and rotation-invariant in a given angle range pattern recognition system. Although rotation-invariant angle is restricted to centain extents, the ratio of signal to noise might be increased, meanwhile we need not measure the phase factor of correlation function between target and recognition image in order to determine the rotation angle instead of directly measuring the absolute value of correlation function. We also give one simple example to demonstrate this design and compare it withthat suggested by Hsu et al.
THE SIMPLIFICATION OF X-RAY ANOMALOUS DISPERSION METHOD IN DETERMINING PARTIAL RADIAL DISTRIBUTION FUNCTION (PDF) OF THE AMOPHOUS BINARY ALLOY Fe82B18
1985, 34 (6): 766-773. doi: 10.7498/aps.34.766
The radial distribution function (RDF) of amorphous alloy Fe82B18 was determined by using three different wave lengths of X-ray radiation (Mo, Cu, Co). And their influences on the determination of RDF were compared.The PDF for amorphous binary alloy Fe82B18 were calculated by means of X-ray anomalous dispersion method. In the calculation, the contribution of B-B atom pairs to RDF was neglected. Therefore, the calculation procedure was simplified and the accuracy of calculation increased.
1985, 34 (6): 774-783. doi: 10.7498/aps.34.774
The changes of electronic structures in the metallic superlattices due to disorder have been calculated self-consistently by CPA method for a simple model hamiltonian, using tight-binding approximation and only the random distributions of diagonal matrix elements being taken into account. The local densities of electronic states and the curves of self-energy have been obtained for some values of the parameters.
In this paper, based on a physical picture of the unified theory of the low frequency fluctuation, dissipation and relaxation phenomenon, some transport features of a non-Markovian process are explored. It is found that: (1) due to the effect of infrared divergence the diffusion coefficient, the mobility, and the viscosity as well as the generalized MD relation (MD) (i.e., Nernst-Einstein relation) and the generalized DV relation (DV) which exist among these coefficients, in general, are dispersive and the degree of the dispersion depends on a single parameter n, the infrared divergence exponent. If n goes to zero, all results immediately reduce to the classical forms; (2) the MV relation, neither depending on the nature of the transport process nor on the structure of the medium, seems to be generally valid and (3) the functional form of the generalized diffusion coefficient is identical with that of the generalized mobility, and that of the MD relation with that of the DV relation. The prediction of the dispersive diffusion is in good agreement with the recent experiment. The MD relation has been surmised ought to exist. If it exists, the prediction of dispersive mobility would be true.
1985, 34 (6): 796-800. doi: 10.7498/aps.34.796
The resonant curve of a rectangular surface water wave resonator can bend to lower frequency or to higher frequency, depending upon the depth of equilibrium water level. Besonant curves of finite amplitude water surface wave for various water level are measured. The crossover height at which the bending doesn't occur is determined.
MAGNETIC PROPERTIES OF THE RANDOM MIXTURE OF THE ONE-DIMENSIONAL SYSTEM WITH ANISO-TROPIC HEISENBERG EXCHANGE
1985, 34 (6): 801-808. doi: 10.7498/aps.34.801
In this paper, we extend the method proposed in ref.  for the calculation of the partition function of the anisotropic Heisenberg spin system, and calculate the specific heat and magnetic susceptibility for random binary mixture of the one-dimensional system with anisotropic Heisenberg exchange.
1985, 34 (6): 809-812. doi: 10.7498/aps.34.809
Measurements have been made at 4.2-30 K for the thermal conductivity of a poly-crystalline Fe-25Mn-5Al-0.2C sample with negative temperature coefficient of resistivity. It is found that the phonon conductivity is anomalously proportional to T. The suggested explanation is that this phenomenon results from the noneffectiveness of the scattering of phonons by electrons, when electrons have short mean free path caused by addition of Al.
1985, 34 (6): 813-819. doi: 10.7498/aps.34.813
After bombarding the Mo (001) and Mo (110) surfaces contained trace amount of carbon and oxygen with nitrogen ions of the energy of 1 keV and the beam current of 6 μA for 10-15 min, a very strong Auger pcak of nitrogen appeared in AES.The LBED observation showed that surface structure was disordered from room temperature to 350℃ annealing. When the sample was heated to the temperature range530-650℃, three types of LEED pattern, i. e.,c(2×2)-N, p(2×2)-N and (4(21/2)×21/2 R45°-N, O formed on Mo(001). In the case of Mo (110) only one type LEED pattern of c(7×3)-N was observed.The fact that the LEED structure of surface related to thermal desorption indicates that ordered structure depends on coverage of notrogen and temperature, and provi--des some information about phase transformation on the surface.
1985, 34 (6): 820-822. doi: 10.7498/aps.34.820
The peak effect of the Pb-40 wt% In alloy specimen in a longitudinal magnetic field is observed. The critical thickness d0 is estimated.
1985, 34 (6): 823-827. doi: 10.7498/aps.34.823
β-BaB2O4 crystal is a new-type ultraviolet SHG crystal as found in our Institute for the first time. In this paper, on the basis of our theoretical work of "An anionic group theory of non-linear optical effects of the crystals" and the theory of odd-ordered crystal field produced by A-site cation, we have calculated SHG coefficients of β-BaB2O4 crystal by using CNDO/S approximations. The calculated values agree satisfactorily with the experimental data, for both absolute values and relative sign of the above coefficients. The result shows that the conjugate π orbitals of anionic group (B3O6)3-give major contribution to the SHG coefficients. Moreover, it also shows that the CNDO/S-approximation is a suitable method for calculating molecular orbitals of cova-lent-bonded (B3O6)3- group in crystals.
1985, 34 (6): 828-832. doi: 10.7498/aps.34.828
The microwave-radio frequency multi-quantum transition in optical pumping experiment is studied for different r.f. power. The microwave-r.f. subharmonic multi-quantum trasition has also been observed.
1985, 34 (6): 833-840. doi: 10.7498/aps.34.833
A quantum-statistical model for a three-level cascade atom interacting with radiation fields initially in coherent states is presented. By means of numerical summation and saddle-point approximation, the expectation values of the atomic-level operators and the photon numbers are obtained and discussed, which reveals the phenomena such -as the twophoton transitions and the new collapse and revival.
MONTE CARLO SIMULATIONS OF SU(2) LATTICE GAUGE THEORY WITH THE NEW ACTIONS BY USING THE DISCRETE SUBGROUP
1985, 34 (6): 841-844. doi: 10.7498/aps.34.841
Monte Carlo simulations of the SU(2) lattice gauge theory with SIN action and EXP action are performed by using the icosahetral subgroup. We obtain that the first order phase transition points due to the nature of discrete subgroup are βc′≈9.2±0.2 and βc′= 6.8±0.2 respectively. The plaquette energy and specific heat of present case are in good agreement with that of the SU(2) group. Therefor, we verify that for two kinds of actions mentioned above, using discrete subgroup instead of SU(2) group is reasonable and provides the foundation for further calculations by means of the icosahetral subgroup.
1985, 34 (6): 845-848. doi: 10.7498/aps.34.845
A Monte Carlo simulation of the SU(2) lattice gauge system with a Sp=sin 1-sin (TrUp/2) action on a 10 lattice is performed. The ratio between string tension and scale constant is calculated. It is shown that the average internal energy per plaquette and the peak of specific heat are insensitive to the lattice volumn.