Vol. 40, No. 1 (1991)
1991-01-05
GENERAL
1991, 40 (1): 1-7.
doi: 10.7498/aps.40.1
Abstract +
By using the direct method of Hirota, explicit multi-soliton solutions are found for the generalized nonlinear Schr?dinger equation with higherorder corrections which describes the ultra-short pulse propagation along monomode optical fibers.
1991, 40 (1): 8-13.
doi: 10.7498/aps.40.8
Abstract +
We point out that there exist the soliton solutions of the KdV equation running to the left, as well as static and the interaction solutions between left running and right running solitons. The larger the amplitude of the left running soliton is, the slower it moves.
1991, 40 (1): 14-24.
doi: 10.7498/aps.40.14
Abstract +
As a form of density matrix, the Wigner function is the distribution in quantum phase space. It is a 2×2 matrix function when one uses it to describe the non-relativistic fermion. While describing the relativistic fermion, it is usually represented by 4×4 matrix function. In this paper we obtain a Wigner function for the relativistic fermion in the form of 2×2 matrix, and the Liouville equation satisfied by the Wigner function. This equation is equivalent to the Dirac equation of charged fermion in QED. Our equation is also equivalent to the Dirac equation in the Walecka model applied to the intermediate energy nuclear collision while the nucleon is coupled to the vector meson only (or taking mean field approximation for the scalar meson). We prove that our 2×2 Wigner function completely describes the quantum system just the same as the relativistic fermion wave function. All the information about the observables can be obtained with our Wigner function.
1991, 40 (1): 25-32.
doi: 10.7498/aps.40.25
Abstract +
In this paper, we find the exact solution for the generalized time-dependent harmonic oscillator by making use of the Lewis-Riesenfeld theory. Then, the adiabatic asymptotic limit of the exact solution is discussed and the Berry's phase factor for the oscillator obtained. We proceed to use the exact solution to construct the coherent state and calculate the corresponding classical Hannay angle.
1991, 40 (1): 33-38.
doi: 10.7498/aps.40.33
Abstract +
The results of both the computer and laboratory experiment show that the nonliner function in the dynamic system bears a special property, that of jump stochasticity. This special property makes the nonliner function to produce a number of jump stochasticity curves which are different from that of itself.
ATOMIC AND MOLECULAR PHYSICS
1991, 40 (1): 39-42.
doi: 10.7498/aps.40.39
Abstract +
Fine structrue of the band at 363.52 nm in multiphoton ionization spectrum of SiH4 has. been observed using dye laser with 6×10-4nm scanning step. In the case of three-photon resonant excitation, SiH4 is treated as a a symmetric top. Most rotational lines have been resolved and acounted for as a Q-branch of v2 perpendicular band, and B＇= 3.04±0.01 cm-1 is thus obtained.
CLASSICAL AREA OF PHENOMENOLOGY
1991, 40 (1): 43-48.
doi: 10.7498/aps.40.43
Abstract +
The relaxation time of excited state of FeTTP in CHCl3 has been measured by laser frequency domain technique. The relaxation time of the first excited state is obtained to be 0.82 ps by the numerical fitting for the experimental curve.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
1991, 40 (1): 49-55.
doi: 10.7498/aps.40.49
Abstract +
The stability of m = l,n = l internal kink mode in tokamak plasma with anisotropic energetic circulating particle component is analyzed by using the generalized energy principle. The stabilizing effect from the barely circulating particles is proved. The similarity and difference of the stabilizing effect on the internal kink mode from the energetic trapped particles and energetic circulating particles are compared, based on physical picture.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1991, 40 (1): 56-63.
doi: 10.7498/aps.40.56
Abstract +
The GexSi1-x/Si superlattice with 23 periods was grown by molecular beam epitaxy. The X-ray diffraction pattern was measured using a computer-controlled X-ray diffractometer with Cu Ka radiation. Interference peaks due to the superlattice structure were observed up to the 13th order. The superlattice period and the Ge average composition can be determined from the interference peak angles based on a modified Bragg's law, which was derived by including the X-ray refraction at the superlattice surface and interfaces. The structural parameter can be determined by analyzing the X-ray diffraction pattern based on the optical multilayer reflection theory. The intensity ratio of the 2nd peak to the 1st peak is quite sensitive to the variation of the thickness ratio of the two components. By comparing the calculated value of I2/I1 to the experiment, we can determine the thicknesses of Si and GexSi1-x layers, and finallv x. The diffraction pattern calculated using the optical mutilayer reflection theory was in accordance with the measured ones.
1991, 40 (1): 64-69.
doi: 10.7498/aps.40.64
Abstract +
The crystal stucture and phase transition of PrP5O14 have been studied by X-ray diffraction methode. The crystal belongs to monoclinic system at room temperature. The structure parameters are as follows: a = 8.777(l)?, b = 9.029(2)?, c= 13.068(2)?, β=90.35°(l), z=4. The space group is P21/c. The final R is 0.046. The monoclinic system transforms to an orthor-hombic phase at 130±5℃. The point-group changes from 2/m to mmm. The monoclinic system contains mmmF2/m ferroelastic domain. The lattice parameters with orthorhombic phase are a = 8.813(7)?, b = 9.075(2)?, c = 13.119(10)?. The space group is Pncm. Finally, the relationship between the crystal structure and ferroelastic behavior are discussed.
1991, 40 (1): 70-77.
doi: 10.7498/aps.40.70
Abstract +
XRD technique was employed to examine Sm-modified PbTiO3 piezoelectric ceramics with typical ultra-high electromechanical anisotropy. By introducing crystal plane orientation density ρ(hkl) and establishing wall translation model for 90°ferroelectric domain switching, a quantitative analysis and discussion on the domain texture change within the ceramic disks poled at various electric forces has been carried out. The results indicate that 90°domain walls in the modified PbTiO3 ceramics show a strong spatial orientation preference, and little changes in their orientation can result from poling treatment but noticeable wall displacement appears. Another noteworthy result is that the thickness electromechanical coupling coefficient Kt develops with poling field almost at the same pace as the orientation density gain △ρ(002) of the crystal plane (002).
1991, 40 (1): 78-83.
doi: 10.7498/aps.40.78
Abstract +
The surface morphology and interior flaws of KTiOPO4 (KTP) crystals grown in pota-sium polyphosphates flux solution were observed with optical microscopy. The fluctuation pattern of bulk supersaturations across the layer-like floss in the crysrals was obtained with scanning electron microscope and energy spectrum analysis. Based on the above results, the causes and process for the formation of macro inclusion-layer-like floss due to the high in-homogeneity of solute distribution on the grown face under some inappropriate growth conditions were elucidated. The flossless and transparent KTP crystals have been grown rapeatedly when the cocentrations of solution were located in the region of critical bulk supersaturation for steady growth, namely the σ was everywhere larger than the lower limit (～1.3) of the region.
1991, 40 (1): 84-88.
doi: 10.7498/aps.40.84
Abstract +
The experimental results of polarized Raman scattering in KBr: Pb2+ single crystal after a long X-irradiation at 77K are reported in this paper. Based on the recently developed Behavior Type analysis method, it is confirmed that the peak at 186 cm-1 in Raman spectrum of KBr: Pb2+ corresponds to the vibration mode A′ of HD center with the symmetry of point group C1k(010).
1991, 40 (1): 89-92.
doi: 10.7498/aps.40.89
Abstract +
The surface microstructures of spherical Pt single crystals are studied by reflection electron microscopy, and the defect configurations in the crystals are also analysed. Dislocations and low angle grain boundaries appear in the initial stage of the solidification of liquid drops. In the following annealing, the dislocation density decreases and single crystals are formed owing to the movements of dislocations in the grains to the subgrain boundaries, and those in the subgrain boundaries to the surfaces of crystals.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1991, 40 (1): 93-101.
doi: 10.7498/aps.40.93
Abstract +
The electronic structures of high Tc superconductors YBa2Cu2ScO7, including two cases of Sc substituting Cul and Cu2 sites, are studied. Sc-Cu2 replacement has effects on electronic structure of Cu-O layers, which may possibly destroy the high temperature superconductivity. However, our calculations show that it is more likely for Sc to substitute Cul site. It is shown that the overlapping splitting between the major bonding partial wave of Sc and its remaining four 3d orbitals is as large as 4eV. Thus one can detect experimentally, by near infrared fluorescence, whether Sc substitute Y or Cu sites in Sc-Y-Ba-Cu-O materials.
1991, 40 (1): 102-108.
doi: 10.7498/aps.40.102
Abstract +
In order to explain why the enhancement or reduction of dimerization of polymer is only determined by the range of electron interaction, the diagonal and off-diagoal matrix elements of screened Coulomb interaction are calculated, and it is shown that the off-diagonal matrix elements are getting more and more important when the interaction range decreases. The Competition between the off-diagonal and diagonal interactions causes the transition from enhancement of dimerization to reduction.
1991, 40 (1): 109-116.
doi: 10.7498/aps.40.109
Abstract +
A model Hamiltonian is presented to describe halogen-bridged mixed-valence platinum complex (HMPC), the Green function is used to calculate the electrical conductivity of doping HMPC, the dope induced defect states are discussed in detail, the results are in agreement with experiments satisfactorily.
1991, 40 (1): 117-121.
doi: 10.7498/aps.40.117
Abstract +
The "irreversibility line" of high Tc fluorine-doping Bi(Pb)SrCaCuO(F) bulk superconductor has been studied experimentally. It is shown that there are different H*∝(l-t)3/2 relations in various regions of magnetic fields, namely, H*=1590(1-t)3/2 in the field region below 120 Oe and H*= 35700(1-t)3/2 -2480 in the region above 120 Oe. We think that the irreversibility lines in low field and in high field represent the behaviour of weak link and the grain superconductivity respectively. We note that H*(T) is substantially a melting line of the flux lattice. It is in the vortex lattice state below the "irreversibility line" H*(T) and in the vortex liquid state between H*(T) and H(c2) (T) curves.
1991, 40 (1): 122-126.
doi: 10.7498/aps.40.122
Abstract +
The reaction process of formation of the Bi-Pb-Sr-Ca-Cu-O superconductor by means of a three-step reaction method was studied by high-temperature X-ray diffraction meansurement and DTA technique. The 2212 phase began to form at about 740℃ from the mixture of the Bi-Pb-Sr-Ca-O precursor-CuO, and the 2223 phase at about 825℃. The 2212 phase melted incongruently to the 2201 phase and a liquid phase at about 875℃ and the 2223 phase melted a liquid phase at about 935℃. In the crystallization of the 2212 phase, strong c-orientation forms easily.
1991, 40 (1): 127-136.
doi: 10.7498/aps.40.127
Abstract +
In this article, we discuss two important problems about possible superconductivity in organic molecules. One problem concerns the instability of an one-dimensional metal (Peierls distortion). The other is associated with screening of the Coulomb interaction between electrons in organic molecules. First, using Bloch function to describe electronic states, we have shown that some screening of the Coulomb field in organic molecules must occur. The square of screening length is inversely proportional to the density of states at the Fermi level. Next, we have found that for polyacenacene the regular structure is stable with respect to the Peierls distortion, and that bond alternation does not happen. Moreover, polyacenacene has large density of states at the Fermi level, which makes the effective interaction attractive, and the presence of polarizable substituents superconductivity will be possible if other requirements are met.
1991, 40 (1): 137-141.
doi: 10.7498/aps.40.137
Abstract +
Ferromagnetic Resonance spectra of (Fe1-xCrx)84B16 amorphous alloys and the change of spectra with temperature have been observed in the temperature range 106 K to 430 K. The FMR spectra are multipeak. The variation of line width △H with T has been discussed. This is an experimental verification of "independent grain approximation".
1991, 40 (1): 142-148.
doi: 10.7498/aps.40.142
Abstract +
The influence of electrolytic hydrogenation on the magnetic properties of three kinds of soft magnetic amorphous alloys with diffrent composition has been investigated. The experimental results showed that, after hydrogenation, the samples became very brittle and the soft magnetic properties of these alloys were seriously damaged, but the saturation magnetization and the average hyperfine field Hhf increased remakably. The experiments also showed that the hydrogen escaped gradually from the samples when they were left in air at room temperature and the magnetic and mechanical properties as well as the Hhf could recover gradually.
1991, 40 (1): 149-153.
doi: 10.7498/aps.40.149
Abstract +
The electron paramagnetic resonance spectra of the natural single crystal of the tetragonal structure zircon containing impurity Gd3+ have been measured. The fine structure parameters were calculated using a least-squares fitting procedure. The hyperfine structure for odd isotopes 155Gd and 157Gd was clearly resolved, and the values of the hyperfine coupling constant to first order were given.
1991, 40 (1): 154-160.
doi: 10.7498/aps.40.154
Abstract +
The silicon dioxide film of thickness 150? with device quality has been nitrided thermally by conventional long time method and high temperature rapid method. For the films breakdown characteristics and endurance under high field were investigated. These results indicate that after nitridation, the distribution of breakdown field strength narrows, its dependence on electrode area decreases, and the maximum breakdown field strength degrades slightly. At the same time, SiO2/Si interface stability under high field and time-dependent dielectric breakdown characteristics are improved by thermal nitridation. The improvement depends strongly oh both the electrode direction of applied gate voltage and nitridation processing condition. According to the mechanism of current transport, we suggest a breakdown model in which charge accumulation, trapping density and position of its center of gravity are all considered.
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
1991, 40 (1): 161-168.
doi: 10.7498/aps.40.161
Abstract +
The calculation of order parameteres with variant temperature in Ll2 structure has been carried out in this work by means of Monte Carlo method statistical physics. The order interaction of the nearest neighbour J1 and three kinds of order interaction of next neares' neighbour J2= 0, - 0.3J1 as well as 0.3J1 were considered in this calculation. The results show that the calculation value of the critical temperature Tc (order-disorder transition temperature) of the first order phase transformation is in good agreement with that obtained by some other theories, such as quasi-chemical method; and Tc is sensitively affected by J2, that may be regarded as an interpretation about the action of interstitial atoms in Ll2 structure.
