Vol. 48, No. 10 (1999)
1999-05-20
GENERAL
1999, 48 (10): 1781-1792.
doi: 10.7498/aps.48.1781
Abstract +
Starting from two-line soliton solution of an integrable (2+1)-dimensional system in bilinear form,one can find a dromion solution that is localized in all directions for a suitable potential.The in-teraction between two dromions is studied in detail through the method of figure analysis for (2+1)-dimensional NLBQ equation and KP equation.Except for a phase shift,there are no changes on the shape and velocity of the dromions after interactions for these models.The interactions of dromions for these models are not only elastic (there is no exchange of energy)but also irrotational (there is no exchange of angular momentum).
1999, 48 (10): 1793-1799.
doi: 10.7498/aps.48.1793
Abstract +
A falling-in physical particle in metric and electromagnetic tensor field of Schwarzschild and Kerr-Newman black hole is studied.It is concluded that the physical particle will not make the outer horizon smaller.This is coincident with the area theorem.It is well known that δA≥0 andδκ≤0 are the necessary condition for changing from nonextremal to extremal Kerr-Newman black hole.We demonstrate that the surface gravity (temperature) of a Kerr-Newman black hole cannot be reduced to zero in a finite sequence of physical interactions.This is coincident with the third law of black hole thermodynamics.We also consider the trend of area change in the evolution of near-extremal black hole.The effect of negative heat capacity and the entropy renormalization are discussed.
1999, 48 (10): 1800-1803.
doi: 10.7498/aps.48.1800
Abstract +
A lattice Boltzmann method for two-dimensional convection-diffusion equation is presented in the paper.The tunable parameters in Chapman-Enskog expansion of the local-equilibrium distribution function are determined in the form of convective coefficient and diffusive coefficient.Some discussion on the method is made.
1999, 48 (10): 1804-1809.
doi: 10.7498/aps.48.1804
Abstract +
A new method of controlling unstable fixed points in discrete nonlinear systems is suggested in this paper.The method of choosing combination coefficients and feedback coefficients is give.This method is applied to Logistic map and analogous Henon map.Good results have been obtained.
1999, 48 (10): 1810-1817.
doi: 10.7498/aps.48.1810
Abstract +
We apply the wavelet multiscaling decomposition algorithm,which has been developed for noise reduction,to the extraction of periodic signal,noise and other chaotic signal from chaotic back-ground.This algorithm utilizes the characteristic that wavelet transform has an outstanding local fea-ture in time-frequency domains and it is a linear transform.Therefore it can distinguishes signals with different scales.In contrast to the previous methods our method uses the feature of signal scales and dose not demand restrictive assumptions that we must know the mathematical model of the chaotic background and that the amplitude of signal is smaller than that of the chaotic background.The re-sults of computer simulation are given for extracting the sine signal,white noises (distributed uni-formly or in Gaussion shape) and Chua's chaotic signal from Lorenz chaotic back ground.
1999, 48 (10): 1818-1822.
doi: 10.7498/aps.48.1818
Abstract +
Chaotic behaviors in a self-mode-locked Ti:sapphier ring laser are reported.The Regular,peri-od-doubling,quasi-periodic and chaotic behaviors are observed under some control conditions.The ex-perimental observations are in agreement with the theoretical predictions by V.L.Kalashnikov et al.
1999, 48 (10): 1823-1830.
doi: 10.7498/aps.48.1823
Abstract +
Using the criterion of the free energy,we prove that the mechanical equilibrium condition for liquid droups on the condenser surface depends on the angle of contact (α).For α＞90°the chemical potential of liquid drops on the condenser surface is less than that of spherical drops with the same curvature.And the critical radius of the former is also less than that of the latter if they are at the same saturation level.For this reason the heat-transfer capability of liquid drops condensed on the walls of a vessel is stronger than that of the condensed liquid film.The suitable value is determined for the angle of contact.
1999, 48 (10): 1831-1838.
doi: 10.7498/aps.48.1831
Abstract +
With the consideratioin of both defocused and abaxial cases,the analytical expressions for the 3D transfer function of optical low coherence tomography are derived in this paper.The theoretical stud-ies are concerned with the resolution-related factors,which furnish evidences for the designation and optimization of the systems.According to our study,the axis resolution would increase linearly with the spectral bandwidth,while the signal level would decrease linearly.In the case of defocused scan-ning,although longer focus length and narrower beam aperture could result in an absolute decrement of the resolution,they give an even better defocused imaging property in the whole scanning region.The detected waveform and the actual image of the optical coherence tomography are also given.
NUCLEAR PHYSICS
1999, 48 (10): 1839-1844.
doi: 10.7498/aps.48.1839
Abstract +
The emission of light particles (LP),charged particles (CP),intermediate mass fragments (IMF) and the largest fragment(MAX) for 129Xe is investigated in the frame of lattice gas model.Definite turning points for the slopes of average multiplicity of LP,CP and IMF,mean mass of the largest fragment(Amax)and mean excitation energy per nucleon(E*/A)of the dissociation source against temperature are shown at 5—5.5MeV,where the largest variances of the distributions of LP,CP,IMF,MAX and E*/A are observed also.Furthermore,the slopes of these variances with temperature show discontinuities at the same temperature.All these features indicate that the largest critical fluctuation is simultaneously accompanied by the critical phenomenon and phase transition at the turning temperature in the lattice gas model.
ATOMIC AND MOLECULAR PHYSICS
1999, 48 (10): 1845-1851.
doi: 10.7498/aps.48.1845
Abstract +
Modulation Transfer Spectroscopy (MTS) has been proved to be a very effective method in laser stabilization.The asymmetric sidebands shift the line center of the MTS spectrum,and then re-duce the long term stability and reproducity of laser frequency.In this paper the formula for the line shape of MTS is derived based on the density matrix equations.The formula is applied for the calcu-lation of either the symmetric or asymmetric sidebands.Using this formula,The frequency shift due to the asymmetricity of the sidebands i s estimated.
1999, 48 (10): 1852-1857.
doi: 10.7498/aps.48.1852
Abstract +
The pressure-broadened cross section (kinetic energy of the collision range:30 cm-1—1000cm-1) and the avarage relaxation cross section (temperature of the interaction system:125K,175K,300K) for pure rotational dipole transition of HCl in Ar are calculated,by employing infinite or-der sudden approximation (IOSA) and Ar-HCl H6(2) analyti potential energy surface of Hutson.Comparing the IOSA results with Close-Coupling results and experiments,we find that IOSA can give satisfactory results for j=0←j=1 transition line of the molecules which have large rotational constant.Unfortunately,modfication must be performed for using IOSA in the exitation of transition lines.
1999, 48 (10): 1858-1863.
doi: 10.7498/aps.48.1858
Abstract +
A distorted -wave Born exchange (DWBE) approximation is used to calculate the resonance-ex-citation double autoionization (REDA) for the Li Isoelectronic sequence.Comparison shows good a-greement between the present calculation and experimental data and other theoretical results.In this paper,our research is focused on the effect of the configuration-mixing and radiation channel on the REDA,and the REDA contribution to the ionization process.Also their variation with ion charge Z is given.
CLASSICAL AREA OF PHENOMENOLOGY
1999, 48 (10): 1864-1868.
doi: 10.7498/aps.48.1864
Abstract +
In this paper the laser linewidth without rotating wave approximation is studied by keeping the ratio of the atomic natural decay rate to the radiation frequency to two orders.It is shown that while the linewidth is confined to the Schawlow-Townes formula,the non-rotating wave terms would cause the linewidth to increase since the non-rotating wave terms decrease the average photon number.The degree of increasing in linewidth depends not only on the square of the ratio of the atomic natural de-cay rate to radiation frequency,but also on the average photon number in rotating wave approxima-tion.The influence of the non-rotating wave terms on the laser linewidth is much larger than on the photon number fluctuations.
1999, 48 (10): 1869-1874.
doi: 10.7498/aps.48.1869
Abstract +
Based on the second moments method and orthogonal basis mode expansion,analytical expre-sions for the M2-factor and mode coherence coefficients of sinh-Gaussian beams have been derived,thus the coherent-mode decompositions of sinh-Gaussian beams have been made.A simple method has also been proposed to produce sinh-Gaussian beams in the laboratory.
1999, 48 (10): 1875-1883.
doi: 10.7498/aps.48.1875
Abstract +
In this paper,we have studied experimentally the properties of the mode structure and modes evolution of a slab waveguide CO2 laser with a far field intensity distribution of a single spatially sup-pressed peak. It has been found that the laser mode is a new single mode of a slab waveguide CO2 laser,which has a different mode structure from the known mode of slab waveguide gas laser.
1999, 48 (10): 1884-1890.
doi: 10.7498/aps.48.1884
Abstract +
A kind of tunable frequency-selective converter based on nondegenerate four-wave mixing (ND-FWM) in semiconductor laser amplifier (SLA) is proposed in this paper.The coupling model of the frequency-selective converter in SLA is established first,and then the converting mechanism and characteristics are analyzed.The influences of its property parameters on the output efficiency,and the frequency shift are primarily discussed.And the property of the output noise of the frequency-se-lective converter has been studied as well.The superior performance of the converter,such as short response time,high conversion efficiency,and large conversion range,makes it favorable for use in DWDM networks where high speed and tunableness are required.
1999, 48 (10): 1891-1897.
doi: 10.7498/aps.48.1891
Abstract +
Based on the diffraction integral theory,the near far-field characteristics of a laser-beamtrans-formed random phase plate have been studied theoretically and numerically ain a rather general case.The spot smoothing,profile controlling and speckle inhibiting by introducing the random phase plate have been analyzed in detail.Some new results obtained here are useful for practical applications of the random phase plate.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1999, 48 (10): 1898-1903.
doi: 10.7498/aps.48.1898
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In this paper,numerical calculations of magnetically induced twist effeet in planar nematic liquid crystal are presented.The transmission of polarized light passing through magnetically induced twist distribution in planar nematic liquid crystal is calculated with “4*4”matrix algorithm.On the ex-perimental side,the optical phase retardation method is used to detect the magnetically induced twist effect in planar nematic liquid crystal 5CB(4′-n-penty1-4-cyanobiphenyl) at 27℃.Theoretical cal-culation and experimental results illustrate that polarized light can be used to study the twist effect in thin sample of planar nematic liquid crystal.
1999, 48 (10): 1904-1910.
doi: 10.7498/aps.48.1904
Abstract +
Using first principles total energy calculations,the surface energies of Mo and W before and af-ter adsorbing Rh thin films in [111] and [110] orientations are calculated.The calculation results indicate that clean (111) surfaces of both Mo and W cannot transform to {110} facets,in agreement with experimental observations.When the coverage of Rh arrives at one physical monolayer,Rh/Mo(111) still cannot facet to {110},while under a favorable energy condition for the transforma-tion,Rh/W(111) may facet to {110}.
1999, 48 (10): 1911-1916.
doi: 10.7498/aps.48.1911
Abstract +
The multifractal approach was used to describe the failure process of organic thin film electrolu-minescence observed with fluomicroscope dynamically.It was found that the failure of the electrolu-minescence resulted from the bubbles generated at the interface between the organic layper and the metal electrode.The bubbles became more and more numerous during the device working.Multifrac-tal spectra showed that the longer the working time or the higher the loaded voltage of the device,the narrower the spectrum.This result was in good agreement with the experimental observation.
1999, 48 (10): 1917-1922.
doi: 10.7498/aps.48.1917
Abstract +
Based on the ahievement of epitaxial growth in several Perovskite oxide films,we discuss the importance of substrate temperature (Ts) and substrate material in the epitaxial growth of per-ovskite oxide thin films.Influences of Ts on growth orientation and epitaxial threshold temperature were observed.The results indicate that during the growth of the oxide films the phase formation and growth dynamics should be taken into considera tion.The threshold temperature for epitaxial growth depends on the substrate materials.This demonstrates the influence of substrate material on the initial nucleation and epitaxial growth.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1999, 48 (10): 1923-1929.
doi: 10.7498/aps.48.1923
Abstract +
The electronic structure in UV-VUV region of PbWO4 crystaly is studied in a molecular-cluster model within the framework of the fully relativistic self-consistent Dirac-Slater theory,using a nu-merical discrete variational (DV-Xα) method.From the calculation,the fundamental gap is found to be around 4.4eV,the top of valence band is formed almost purely by O 2p and has certain Pb 6s component in the band,W 5d is at the bottom of the conduction band,Pb 6s narrow band is just be-low the valence band.These results are in reasonable agreement with experimental data measured in the fundamental absorption region using VUV synchrotron radiation.
1999, 48 (10): 1930-1937.
doi: 10.7498/aps.48.1930
Abstract +
The variation of interchain potential in poly (vinylidene fluoride) polymer during chain rotation was calculated.In the case that center chain rotates while all other chains keep static as discussed by “six-site-potential” theory,the potential curves show four high potential barriers owing to the steric effect of fluorine atom from adjacent molecule,which is in contrast to the six-fold sysmmetry pre-dicted by the “six-site-potential” model.It was found that if all chains rotate synchronically, the barrier height will reduce dramatically.The result also indicates that the polarization reversal is ac-complished with the change of lattice constant.The finally obtained barrier height is about 7.5kJ/mol.In comparison with the thermal energy of chain rotation at room temperature (about2.5kJ/mol),the potential well is too shallow to form stable spontaneous polarization.It was specu-lated therefore,the formation of spontaneous polarization in these materials should include some ex-ternal factors.
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
1999, 48 (10): 1938-1943.
doi: 10.7498/aps.48.1938
Abstract +
In consideration of the influence of a planar polythiophene configuration,we study the localized vibrational modes around an electronics bipolaron by using a two-dimensional SSH model.Fifteen lo-calized vibrational modes have been found,among them,four infrared active localized vibrational modes and four Raman active ones could be used to interpret the four observed intense infrared ab-sorption lines at 1020,1120,1200 and 1323 cm-1,and the four Raman active absorption peaks at 700,1047,1175 and 1220 cm-1,respectively.
1999, 48 (10): 1944-1949.
doi: 10.7498/aps.48.1944
Abstract +
VCE method was extended to treat antiferromagnetic-paramagnetic transition,so that it is not only able to calculate the Curie temperature but also the Neel temperature.The formulas for calculat-ing critical temperatures of random-bound layered Ising model,which describes the phase transition in magnetic alloy film,were provided.Some Tc-χ phase diagrams for magnetic alloy film were investi-gated and discussed.
1999, 48 (10): 1950-1956.
doi: 10.7498/aps.48.1950
Abstract +
The etching properties of amorphous hydrogenated carbon films deposited from benzene vapor in a multipole electron cyclotron resonance (ECR) plasma-enhanced chemical vapor deposition system have been investigated.Etch rates of these carbon films as a function of the process variables,includ-ing gas pressure and microwave power were measured,and compared with other resist materials.The results show that the film has high etching resistance against oxygen,and etch rate of the film not only closely correlated with etching process parameters,but also with the deposition conditions.This film could be used as a resist in dry etching process.
