Vol. 39, No. 3 (1990)
1990, 39 (3): 337-342. doi: 10.7498/aps.39.337
In the higher-dimensional space-time, the metric coefficients g00 and g11 of both the Schwarzschild and Reissner-Nordstr?m metrics satify the relation g00g11 =-1. Byconsidering that rhe relation between the metric coefficients is valid inside a chargedperfect-fluid distribution, and assuming the mass density σ=σ0rbe-λ(r)/2, weobtain an exact interior solution far a static charged sphere in the higher-dimensional space-time.
1990, 39 (3): 343-350. doi: 10.7498/aps.39.343
In this paper, we have proposed a multiple wires homogeneous suspending fashion for gravitational waves antenna, showed that the strain caused by suspending in the antenna can be reduced arbitrarily to avoid the additional noise excited by restricted phonons, and also proved that the influence of this suspending fashion upon the eigen frequency and the Q factor of the antenna can be neglected. Thus, this suspending fashion may be a perfect supporting scheme.
In this paper, through the discrimination of Farrey sequence and the demonstration of bistable states of the forced Brusselator with weak coupling, it is shown that its phase diagram has the same topological structure with that of the circle map.
ATOMIC AND MOLECULAR PHYSICS
1990, 39 (3): 359-366. doi: 10.7498/aps.39.359
In this paper, a theoretical model for vibrational predissociation (VP) of molecular clusters via intermediate states is proposed. It is shown that molecular intermediate states play an important role in inducing VP processes of molecular clusters. Based on this theory, a statistical dynamics model is established to describe and interpret qualitatively and semiquantatively the experimental line-broadening effects in various molecular clusters. Finally, we discuss the effects of a variety of coupling mechanisms on the energetic structures and the state relaxation processes in molecular clusters.
CLASSICAL AREA OF PHENOMENOLOGY
1990, 39 (3): 367-374. doi: 10.7498/aps.39.367
The theoretical analysis and experimental result of steady-state thermal distortion in hollow cylinder lasers are given in this paper. The basic considerations of a 1 kW average power Nd: glass hollow cylinder laser are presented.
The third order optical nonlinearity in 1-d conducting polymers are investigated with a simple model. The relevant physical effects on the nonlinear polarization are analysed. For third harmonic generation our result is in good accordance with the experiment of prestine polyacetylene.
LONG RANGE CORRELATIONS FOR MICROSCOPIC STOCHA-STIC DYNAMICS IN A NONEQUILIBRIUM STEADY STATE (Ⅰ)——CONSTRUCTION OF THE THEORY OF FLUCTUATING HYDRODYNAMICS IN TERMS OF A STOCHASTIC LATTICE GAS MODEL
1990, 39 (3): 381-390. doi: 10.7498/aps.39.381
We consider a system with a single locally conservative field in a slab geometry with different densities maintained at the two surfaces of the slab. On the basis of flutuating hydro-dynamics, we show that the static-density correlations are long ranged and decay as - l/│x-y│d-2 for dimension d≥3 over distances small compared to the size of the slab.
LONG RANGE CORRELATIONS FOR MICROSCOPIC STOCHA-STIC DYNAMICS IN A NONEQUILIBRIUM STEADY STATE (Ⅱ)——PROVE FOR THE CORRECTNESS OF A MICROSCOPIC STOCHASTIC DYNAMICALMODEL
1990, 39 (3): 391-398. doi: 10.7498/aps.39.391
As a particle model, we investigate a stochastic lattice gas with Kawasaki dynamics. We establish the connection with the fluctuating hydrodynamics. In the case of hard core interaction only we prove the validity of fluctuating hydrodynamics and obtain the corrections which are presumably model dependent.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
1990, 39 (3): 399-407. doi: 10.7498/aps.39.399
Obvious heating effects have been observed in RF heating experiments on CT-6B tokamak, in which microwave beams of frequencies 34.34 GHz and 20.1 GHz generated by two gyrotron systems were launched from top and outside of the device, respectively. It is shown that these heating effects arise becouse of the different heating mechanisms. The former is due mainly to the resonance heating of O mode. The latter belongs to down shift-over dense heating. Its heating mechanism may be the nonlinear phenomena occuring near the high density cut off layer of X mode. A kind of nonlinear heating phenomena (secondary heating) has been observed in two experiments, which may come from the different physical mechanisms.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1990, 39 (3): 408-415. doi: 10.7498/aps.39.408
Reflection High Energy Electron Diffraction (RHEED) intensity oscillations during the growth of alternating Ge and Si layers were observed, and the growth behavior during molecular beam epitaxy of Ge/Si ultra-thin multi-layered structures on Si(l00) and Si(lll) substrates has been studied. By using RHEED intensity oscillation, we have fabricated the Ge(2ML)/Si(2ML) and Ge(4ML)/Si(4ML) ultra-thin superlattices by phase-locking method.
X-ray diffraction showed that the conventionally solidified A165Cu20 Co15 alloy consistes mainly of 2-D decagonal quasicrystal (T phase). SEM reveals that T phase formed the perfect morphology of prismoid with 10/m or 10/mmm symmetry. The bounded planes of primoid correspond to the strong spots in the electron diffraction pattern of T phase.
1990, 39 (3): 420-423. doi: 10.7498/aps.39.420
Diamond-like carbon (DLC) films, prepared by RF plasma CVD, were implanted at a dose of 5×1015Ar/cm2 with various ion energy of 50, 100, 140, 180 keV. Before and after ion implantation, IR absorption spectra, Raman spectra, optical gap Eopt, hydrogen contents and resistivities were measured. The results show that C-H bonds are destroyed and sp2 and sp3 components are decreased during implantation. While the ratio of (sp2/sp3) increases with ion energy. The Eopt, resistivities and hydrogen contents decrease with ion energy increasing. Ho-wever, at 180 keV, the above parameters have no evident change. These results are also discussed in this paper.
1990, 39 (3): 424-428. doi: 10.7498/aps.39.424
The infrared divergence response theory is applied to reorientational relaxation process of OH- in KCl: OH to study the behaviour of low temperature ultrasonic absorption in this system. Our calculation results showed that the thermally activated relaxation process makes the main contribution to the ultrasonic absorption for T>4.5K; as for T<4.5K, the tunneling relaxation process can not been neglected.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1990, 39 (3): 429-436. doi: 10.7498/aps.39.429
Light absorption of polydiacetylene chains has been investigated using Green's function. In tight-binding approximation, we defined a Hamiltonian at first, then computed two-electron Green's function using random phase approximation, discussed some properties of excited-states for PDA's, calculated light absorption spectra and compared with experiments.
1990, 39 (3): 437-445. doi: 10.7498/aps.39.437
The electronic structure of CdSe, CdTe and SnSe are studied using the first-principle scalar-relativistic LMTO-ASA method in the local-density approximation. In the calculation, extra "empty" spheres are introduced on high-symmetry interstitial sites in zinc-blende crystal structure and NaCl crystal structure, and a correction for the leading non-spherical component of the crystal potential is incorporated. The calculated results are compared with the experiment and other non-self consistent calculation.
1990, 39 (3): 446-456. doi: 10.7498/aps.39.446
For the quasi one-dimensional electron systems with coulomb interaction, a new model is presented. The form of effective Coulomb potential is derived. Based on the correlated wave function theory, the many-body wave function is obtained on the basis of the collective oscillation behavior of the electron gas. The pair correlation functions and correlation energies of the different electron densities are obtained. The pair correlation functions obtained in this paper are positive definite and satisfy the normalization condition.
1990, 39 (3): 457-463. doi: 10.7498/aps.39.457
In this paper, starting from the relation between two distinct topological structure, we propose a simple self-consistent method based on the Maxwell-Garnett theory, in order to improve the Bruggeman's effective medium theory (mean-field-type approximation). We derive a general expression for the effective conductivity of a two-phase random composite system. The theoretical results on electric and thermal conductivity for some real materials are in good agreement with experimental data.
HYDROSTATIC PRESSURE STUDIES OF DEEP LEVELS AND RELATED CURRENT MECHANISMS IN Hg1-xCdxTe n+-P PHOTODIODES
1990, 39 (3): 464-471. doi: 10.7498/aps.39.464
Theoretical and experimental studies have been made about the electrical characteristics of Hg1-xCdxTe n+-p photodiodes with x=0.5 at room temperature and at hydrostatic pressures up to 2GPa. The observed "anomalous" pressure dependence of the current-voltage characteristics of p-n junctions, which exhibits in the small bias region, has been satisfactorily explained using a theory which takes into account the pressure dependence of deep levels and its effect on deep level-assisted tunneling current. By fitting the dark current to this theory, two deep levels, D1(=Ev + 0.75Eg) and D2( = Ev+0.5Eg), as well as their respective electron and hole lifetimes, were obtained. The pressure coefficients of deep levels in undoped Hg1-x Cdx Te were also obtained.
1990, 39 (3): 472-478. doi: 10.7498/aps.39.472
The relation between magnetic ordering and superconductivity of YBa2Cu3O7-δ was studied by M?ssbauer effect with 57Fe as probe in Cu lattice. The experimental results can be under-stood qualitatively by non-phonon superconductivity mechanism.
DETERMINATION OF THE ANISOTROPY CONSTANTS Ku AND K1 OF GARNET BUBBLE FILMS BY MEASURING TORQUE CURVES
1990, 39 (3): 479-485. doi: 10.7498/aps.39.479
The dependence of the magnetic torque of single crystal GGG (Gd3Ga5O12) substrates on their geometry and some related physical parameters were studied. A method was proposed to deduce the substrate contribution in determining the uniaxial anisotropy constant Ku and magnetocrystalline one K1. Both Ku and K1 can be acquired from the magnetic torque curves by employing the two-variable regression and using computer. As example, the measured curves of Ku and K1 as a function of temperature were presented.
1990, 39 (3): 486-490. doi: 10.7498/aps.39.486
By means of linearized Holstein-Primakoff transformation and Green function theory, the spin wave dispersion curves are obtained for superlattices consisting of two kinds of Heisenberg antiferromagnetic layers. It is interesting that the results are different in cases that a super-cell contains odd or even number of atomic planes, implying differences in physical properties.
1990, 39 (3): 491-494. doi: 10.7498/aps.39.491
Birefringence image of a large hexagonal lamellar inclusion have been observed in GGG single crystal. The strain field of inclusion and long-rang strain field are analyzed with Brace-Kohler compensator. The theoretical calculation and computer simulation are in agreement with the result of experiment.
1990, 39 (3): 495-500. doi: 10.7498/aps.39.495
The far infrared reflection spectra of Hg1-xMnx Te with different composition in the temperature region of 4.2-300 K are reported. It is demonstrated that there are a gap mode as well as a local mode associated with impurity Mn in HgTe. The gap mode has a frequency of 97 cm-1. The theoretical analysis of the gap mode has been proceeded.
1990, 39 (3): 501-506. doi: 10.7498/aps.39.501
Individual sputtering angular distributions and partial sputtering yields of Ni and Pd from Ni-Pd alloy have been measured at different temperatures, by using the Rutherford back-scattering spectrometry (RBS). The experimental results indicate that the partial sputtering yields of both Ni and Pd have a great change near the Curie temperature (the temperature of magnetic phase-transition of Ni-Pd alloy). Furthermore, the change of Pd partial sputtering: yield is greater than that of Ni. Ni is the preferentially sputtering element, but its preferential sputtering extent decreases during the magnetic phase-transition as taget temperature increases. The phenomena seem to be caused by the reduction of surface binding energies during the magnetic phase-transition, the surface segregation and the enhanced diffusion induced by-ion bombardment.
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
1990, 39 (3): 507-510. doi: 10.7498/aps.39.507
The effect of ageing on resistivity, thermoelectromotive power vs Pt and specific heat of the Ni-14.5Cr-1.5Si(wt%) alloy was studied. After quenching, this alloy experiences a transformation from disorder to short range order. Results showed that the resistivity inereased signifitantly by ageing, but the thermoelectromotive power and specific heat increased only slightly. X-ray diffraction analysis showed that this is caused by the formation of the δ-second phase, which is a Ni2Si compound.