Vol. 42, No. 9 (1993)
1993-05-05
GENERAL
INVERSE OPERATOR METHOD FOR SOLUTIONS OF NONLINEAR DYNAMICAL EQUATIONS AND SOME TYPICAL APPLICATIONS
1993, 42 (9): 1375-1384.
doi: 10.7498/aps.42.1375
Abstract +
In this paper, the inverse operator method (IOM) is described briefly. We have realized the IOM for the solutions of nonlinear dynamical equations by the mathematics-mechanization (MM) with computers. They can then offer a new and powerful method applicable to many areas of physics. We have applied them successfully to study the chaotic behaviors of some nonlinear dynamical equations. As typical examples, the well-known Lorentz equation, generalized Duffing equation and two coulped generalized Duffing equations are investigated by the use of the IOM and the MM. The results are in good agreement with those given by Runge-Kutta method. So the IOM realized by the MM is of potential application valuable in nonlinear physics and many other fields.
1993, 42 (9): 1385-1394.
doi: 10.7498/aps.42.1385
Abstract +
Based on the mean field and Bogoliubov approximations, we linearize the Hamiltonian of a nonequilibrium Bose condensed system, which is created by an external coherent pump field, and coupled to a reservoir. It is found that the dynamical algebra of the linearized Hamiltonian is Heisenberg and SU(1,1) Lie algebra if the coupling to reservoir is not taken into account. By using the methods of coherent state, we obtain its eigenvalues and eigen-functions-direct product of displaced squeezed-number-states and generalized SU(1,1) coherent states. Then we introduce the retarded Green's functions of elementary excitations to calculate its spectrum in the coupling situation, and further give the state functions of exciton system in weakly coupling situation.
GENERAL FORMS OF FIELD EQUATIONS AND FREE PARTICLE'S EQUATIONS OF MOTION FOR THEORIES OF GRAVITATION
1993, 42 (9): 1395-1402.
doi: 10.7498/aps.42.1395
Abstract +
The general forms of field equations and free particle's equations of motion for theories of gravitation are derived from the generalized Lagrangian densities of matter fields and free gravitational fields with the aid of invariant property in the (εmn,ξμ) transformations. The General Relativity, the ECSK theory and the general type R+R2+T2 theory of gravity with torsion are shown all to be the special case of the theory given in this paper.
ATOMIC AND MOLECULAR PHYSICS
1993, 42 (9): 1403-1409.
doi: 10.7498/aps.42.1403
Abstract +
The fluorescence spectrum from a three-level atom in V configuration driven by strong coherent laser fields and the time-dependent squeezing effect in the fluorescence fields with different mixtures of the spectrum lines are investigated analytically.
1993, 42 (9): 1410-1415.
doi: 10.7498/aps.42.1410
Abstract +
The interaction of thermal alkali atoms on hot tungsten and platinum filaments has been studied experimentally. The positive ion current has been measured as a function of the surface temperature. Electron exchange between the adatom and metal surface and the change of work function of the adsorbed metal surface have been discussed.
1993, 42 (9): 1416-1421.
doi: 10.7498/aps.42.1416
Abstract +
The cross section of inner-shell excitation followed by auto-ionization and total ionization cross section of lithium-like ions by electron impact have been calculated by using a distorted wave Born exchange approximation. The comparison of present data with close-coupling calculation and experimental measurement is satisfactory.
CLASSICAL AREA OF PHENOMENOLOGY
1993, 42 (9): 1422-1430.
doi: 10.7498/aps.42.1422
Abstract +
In this paper, we study the property of the n-plane linear coherent optical-processing system. By using of the similarity theorem of the Fourier transform and the spatial frequency scaling transform, we can show that the value of parameters {zi}n-1 are of little improtance in two special cases. Moreove, we take the coherent optical imaging system and the spatial frequency scaling transform as two examples to demonstrate the validity of the theory proposed ih this paper.
1993, 42 (9): 1431-1437.
doi: 10.7498/aps.42.1431
Abstract +
We consider the property of the n-plane linear coherent optical-processing system in term of the similarity theorem of Fourier transform and the spatial frequency scaling transform. Suppose the initial system has arbitrary {zi}n-1 with zi being the spacing between the ith and (i + l)th planes. First, we can show that the initial system is equivalent to a system with different spacing, {zoi}n-1. Thus the values of system parameters {zi}n-1 are of little importance. Moreover, in this paper, the relation between the integral kernels of two arbitrary n-planc linear coherent optical-processing systems has been considered.
1993, 42 (9): 1438-1442.
doi: 10.7498/aps.42.1438
Abstract +
The optical metric of a strong laser plasma is obtained by using the self-consistent density profile and the ponderomotive force potential for one dimensional isothermal expanding plasma. Its physical signification is explained.
1993, 42 (9): 1443-1451.
doi: 10.7498/aps.42.1443
Abstract +
We have studied the influence of the Kerr effect on the average photon numbers, the degrees of second-order coherence, the degree of interbeam second-order coherence and the Cauchy-Schwartz inequality in the system consisting of an nondegenerate two-photon J-C model in a high-Q cavity filled with a Kerr-like medium.
1993, 42 (9): 1452-1458.
doi: 10.7498/aps.42.1452
Abstract +
In this paper, we develope the auxiliary parameters method to treat thermal-insensitive resonators, derive a new analytic solution applying to any multielement resonator, and analy-ize the stability of resonators、 the thermal-stable charater of output mode and power in detail. Furthermore, by introducing the concept of thermal sensitive degree, we obtain the optimal thermal-insensitive conditions :g1g2=1/2, μ1= 0.
1993, 42 (9): 1459-1462.
doi: 10.7498/aps.42.1459
Abstract +
The method of two-stage coherent optical amplification was put forward based on the principle of two-beam coupling. This not only makes it possible that two pieces of low quality crystals can yield the result that one piece of high quality crystal reaches, but also solves the problem that the amplification coefficient can not be greatly increased by means of one-stage amplification. The feasibility of the method was proved by theoretical analysis and experimental demonstration.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
1993, 42 (9): 1463-1470.
doi: 10.7498/aps.42.1463
Abstract +
Current distributions of glow discharge plasma in 3-D space were theoretically analyzed with analytic method. The characterestics of the current continuity and self consistency of the theory were demonstrated. Deficiencies and inconsistencies in the result obtained from other models were also discussed and analyzed. The present results are believed to be useful and significant in the study of low temperature plasma.
1993, 42 (9): 1471-1478.
doi: 10.7498/aps.42.1471
Abstract +
The wave function of free electron in a strong laser plasma is obtained by solving exactly the Dirac equation in a curved space-time with optical metric for the laser plasma. When the laser field is diminshed to zero, the wave function is naturally reduced to relativistic wave function of free electron. The possible application of the wave function is discussed.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1993, 42 (9): 1479-1484.
doi: 10.7498/aps.42.1479
Abstract +
The YBa2Cu3Oy thin film on LaAlO3 substrate was investigated by triple axis scattering. Stress, main defects in the film and the crystallographic relationship between the thin film and substrate were studied. Experimental results show that the thin film on substrate was slmost totally relaxed and very low strain and stress existed in the film. The film behaves as a "free" bulk layer on the subtrate. The larger mosaic width of the film indicates the film has poor crystallinity and includes a lot of lattice misorientation defects. Misorientations between the film and substrate were observed in both the perpendicular and parallel direction of the surface.
1993, 42 (9): 1485-1490.
doi: 10.7498/aps.42.1485
Abstract +
In this paper, strain relaxed InGaAs/GaAs strained-layer superlattice has been studied by X-ray double-crystal diffraction and topography. By simulating the double-crystal rocking curves using X-ray dynamical scattering theory, important imformation such as the structure, the mechanism and degree of strain relaxation, the misorientation between the superlattice layers and the substrate and misfit dislocation density, and so forth are obtained. The misfit dislocation distribution at the interface between the superlattice layers and the substrate and in the superlattice layers are observed by double-crystal topography.
1993, 42 (9): 1491-1498.
doi: 10.7498/aps.42.1491
Abstract +
Based on pair potential of atoms determined by general nonlocal model pseudopotential and molecular dynamics simulation techniques of NPT ensemble, we investigated micrody-namical behaviors of supercooled liquid Mg-Ca alloy, examined characteristics of atomic autocorrelation functions of density with time、 wavevector and temperature. Results show that, with deseasing temperature, correlation length of autocorrelation function increases. In the supercooling range, the system exhibits structure slowing down phenomenon to some extent. In addition, results of model coupling theory, within the supercooling range in the present paper, are applicalle to liquid Mg-Ca alloy.
THERMODYNAMIC AND KINETIC ASPECTS OF SOLID STATE AMORPHIZATION REACTION IN Ni/a-Si MULTILAYER SYSTEM
1993, 42 (9): 1499-1504.
doi: 10.7498/aps.42.1499
Abstract +
The interfacial solid state reaction was studied in the Ni/a-Si multilayer. The thermody-namic and kinetic aspects of the solid state amorphization was explained according to the calculated metastable free energy diagram. A kinetic reaction model for the solid state amorphization reaction of Ni/a-Si multilayers is developed.
1993, 42 (9): 1505-1509.
doi: 10.7498/aps.42.1505
Abstract +
he diffusion mechanism of the Ni in amorphous Si was studied by in situ X-ray diffraction technique in amorphous Ni/Si multilayer. The temperature dependent diffusivity of Ni in amorphous Si was obtained in the form of Arrheneius relationship. A trap-retarded interstitial diffusion mechanism is suggested to explain the diffusion process of Ni in amorphous Si.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1993, 42 (9): 1510-1514.
doi: 10.7498/aps.42.1510
Abstract +
The electronic structures of the strained superlattice (SLS) (InAs)1 (InP)1 (001)under two strain conditions (free-standing model and InP-substrate model) and the strained bulk materials corresponding to the molecular layers in the SLS as well as the unstrained bulk materials are calculated with the ab initio LMTO band structure method. The average bond energy of molecular layers in the two SLS are determined with the frozen-potential approach. The results show that the average bond energies are well aligned across the interfaces and this alignment is not almost affected by the condition of strain. Thus, the average bond energy can be considered as a very reasonable reference energy level for determined the valence band offset in SLS. The strain effects on the band structures of molecular layers in SLS and on the △Ev values are investigated. Results given by frozen potential approach and using Em as a reference level in this paper are in good agreement with the available experimental datum from XPS measurement.
1993, 42 (9): 1515-1521.
doi: 10.7498/aps.42.1515
Abstract +
We have investigated the effect of the competition between the electron-electron and elec-tron-phonon interactions on the ground state of MX complex and its third-harmonic generation (THG). On the basis of Hubbard model, the Hartree-Fock(HF) approximation is valid in studying the system when the strength of electron-electron interaction U is less then 2t0(t0is the hopping between M dz2 and X Pz orbitals). As a result, we discover that (i) With U increasing, the system changes from charge density wave (CDW) to spin density wave(SDW). (ii )This phase transition takes place at U～1.2t0 and is a first-order one. (iii) At the critical point, the band gap reaches minimum, thus a large THG is obtained. Based on these results, some proposal is put forward to search for nonlinear optical materials.
1993, 42 (9): 1522-1528.
doi: 10.7498/aps.42.1522
Abstract +
The matrix of optical array with aperture in the element is presented by the Fresnel diffraction intergral. The synthetical imaging aberration of the array is dicussed, the condition of eliminating such aberration is satified with α,β, γ,δ conditions. The reference plane should be shifted with the moving of the aperture in the element.
1993, 42 (9): 1529-1531.
doi: 10.7498/aps.42.1529
Abstract +
The photoluminescence spectra of (110) modulation-doped GaAs-AlGaAs het-erostructures grown under high and low carbon background were measured at 4.2K. For high carbon specimen the luminescence peak from the recombination of 2D electrons in channel with holes bound to neutral acceptors was observed, while for low carbon specimen only lines related to bulk GaAs were observed.
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
1993, 42 (9): 1532-1536.
doi: 10.7498/aps.42.1532
Abstract +
We have studied electronic bound states and the localized modes around the soliton after turning on the next-neighbor hopping interaction, based on SSH model. The results show that (1) the electronhole symmetry of the energy band structure implied by SSH model is broken ; (2) the number and location of the bound states trapped by the soliton have changed; (3) a new localized mode have been found; (4)the frequencies of modes have shifted and their localization are strengthened.
GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS
1993, 42 (9): 1537-1542.
doi: 10.7498/aps.42.1537
Abstract +
We try to develop the Weyl gauge theory in a new direction. The Hawking effect in black hole physics can be universally regarded as a compensate effect under the coordinate-scale transformation. The relevant quantum temperature is a pure-gauge potential of the compensate field.
