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Vol. 46, No. 12 (1997)

1997-06-20
GENERAL
MATRIX ELEMENTS OF RAISING AND LOWERING OPERATORS OF AN ISOTROPIC HARMONIC OSCILLATOR
LI GUANG-HUI
1997, 46 (12): 2289-2293. doi: 10.7498/aps.46.2289
Abstract +
A new definition of four kinds of raising and lowering operators of an isotropic harmonic oscillator is given. Their matrix elements and normalizing constants are calculated.
A CONFORMALLY FLAT SOLUTION OF EINSTEIN MAXWELL EQUATIONS FOR A STATIONARY SPHERICALLY SYMMETRIC DISTRIBUTION OF SPHERE POSSESSING BOTH ELECTRIC AND MAGNETIC CHARGES
ZHANG JING-YI
1997, 46 (12): 2294-2299. doi: 10.7498/aps.46.2294
Abstract +
This paper gives a conformally flat interior solution of Einstein Maxwell equations for a stationary spherically symmetric distribution of sphere possessing both electric and magnetic charges. The solution is physically reasonable.
APPLICATIONS OF THE THEORY OF RELATIVISTIC THERMODYNAMICS TO THE SCHWARZSCHILD MATTER SYSTEM IN THE GRAVITATIONAL FIELD
LIU LU-XIN
1997, 46 (12): 2300-2304. doi: 10.7498/aps.46.2300
Abstract +
The matter system in the Schwarzschild gravitational field is discussed in terms of the formal ism of the relativistic thermodynamics. The stellar structure equation is obtained, and both the statical and the moving particle systems are investigated. The solutions derived agree with the Newton theories under the condition of classical approximation.
FREQUENCY CHARACTERISTICS OF THE INPUT THRESHOLDS OF STOCHASTIC RESONANT SYSTEMS
WANG JIA-FU, LIU FENG, WANG JUN-YI, CHEN GUANG, WANG WEI
1997, 46 (12): 2305-2312. doi: 10.7498/aps.46.2305
Abstract +
By simulating the frequency behaviors of the input thresholds in a bistable system and a Hindmarsh Rose neuron, respectively, we study how the input thresholds depend on the frequency of input signal in both non excitable and excitable nonlinear systems in which stochastic resonance may appear. We also present an approximate approach to get the frequency characteristics of input threshold analytically and analyze the unusual minima of the frequency characteristics in excitable systems.
ATOMIC AND MOLECULAR PHYSICS
SOME IMPROVEMENTS ON KELDYSH-FAISAL-REISS THEORY
CHEN BAO-ZHEN
1997, 46 (12): 2313-2319. doi: 10.7498/aps.46.2313
Abstract +
How to insert the final Coulomb interaction into Keldysh-Faisal-Reiss theory is discussed in A guage. The correct low intensity behavior predicted by the improved theory and a brief comparison with that predicted in E guage, then, are shown. Finally, a comment on the numeric result is- given.
LOW ENERGY TRIPLE DIFFERENTIAL CROSS SECTIONS FOR ELECTRON IMPACT IONIZATION OF HELIUM
ZHANG SUI-MENG, CHEN ZHANG-JIN, SHI QI-CUN, XU KE-ZUN
1997, 46 (12): 2320-2324. doi: 10.7498/aps.46.2320
Abstract +
Based on the BBK theory, the influence of momentum correlation in the final state on the triple differential cross sections (TDCS) is considered. Then the TDCS for electron impact ionization of helium at a symmetric coplanar energy sharing geometry are calculated. An excellent agreement with the recent absolute measurement of helium is found in the present calculation, compared with other theoretical models.
CLASSICAL AREA OF PHENOMENOLOGY
PHOTONIC BAND STRUCTURE OF FACE CENTERED CUBIC LATTICE IN CHIRAL MEDIUM
JIN CHONG-JUN, QIN BAI, YANG MIAO, QIN RU-HU
1997, 46 (12): 2325-2329. doi: 10.7498/aps.46.2325
Abstract +
In this paper we develop the plane wave method for calculating photonic band structure in chiral medium through magnetic component, and on this basis, calculate the photonic band structure of the face centered cubic (fcc) lattice made of chiral medium. Result shows that the cut off frequency, below which no propagating modes exist, appears in the two kinds of fcc lattices, i.e.,the array of chiral “spherical atoms” in dielectric material and the array of dielectric “spherical atoms” in chiral matrix. The result is compared with that obtained through electric component, and the difference between them is discussed.
TRANSVERSE DIFFRACTION EFFECTS OF LIGHT FIELDS ON THE GAIN WITHOUT POPULATION INVERSION
ZHANG HAN-ZHUANG, GAO JIN-YUE
1997, 46 (12): 2330-2343. doi: 10.7498/aps.46.2330
Abstract +
We discussed transverse diffraction effects of probe and driving fields on the gain in the model of Raman driven four level atomic system. The calculated results showed that the spectrum of the probe field has different structure compared with that in plane wave approximation due to the transverse diffraction effects of light fields, and the optimum focal position of a focus lens for the maximum gain is in the vicinity of a sample cell.
AN EASY WAY FOR CONSTRUCTING FREDKIN QUANTUM GATE
ZHAN MING-SHENG, ZHANG DENG-YU
1997, 46 (12): 2344-2347. doi: 10.7498/aps.46.2344
Abstract +
We propose a method for constructing Fredkin gate by using basic 2 bit quantum gates,which is based on A.Darenco's work.Compared with H.F.Chau's scheme,this scheme is easier to construct and to understand,as well as to put into practice.
PHASE OPERATOR AND PHASE STATES FOR FINITE ENERGY SYSTEM
TAN WEI-HAN, LIU JUAN
1997, 46 (12): 2348-2358. doi: 10.7498/aps.46.2348
Abstract +
In view of the divergent expectation value of photon number in Pegg-Barnett phase state,in this paper the phase operator,phase states for finite energy system are defined.Its orthogonality,completeness and application in the phase fluctuation calculation are studied.
SMALL AMPLITUDE SOLITON SOLUTIONS OF THE COUPLED NONLINEAR SCHR?DINGER EQUATIONS IN BIREFRINGENCE OPTICAL FIBER
DUAN YI-SHI, YU ZHONG-YUAN, WU ZHEN-SEN
1997, 46 (12): 2359-2362. doi: 10.7498/aps.46.2359
Abstract +
Small amplitude soliton solutions are obtained which satisfy the coupled nonlinear Schr?dinger equations governing optical pulses propagation in the birefringence optical fiber.
ULTRAFAST OPTICAL KERR EFFECT AND OPTICAL INDUCED ABSORPTION OF EMERALDINE BASE
YANG WEN-JUN, SONG YAN-LIN, LUO CHUAN-QIU, CHEN HUI-YING, SHANG XIAO-MING, WANG CONG-FANG, WANG JING-JING, ZOU YING-HUA
1997, 46 (12): 2363-2368. doi: 10.7498/aps.46.2363
Abstract +
The transient optical Kerr effect (OKE) and optical induced absorption of emeraldine base (EB) in dimethylformamide solution have been investigated with femtosecond laser pulses.Only a ultrafast component of OKE of EB solution is observed and its dephasing time is given by theoretical fitting.The third-order nonlinear optical susceptibility of EB solution is also determined.Two-photon absorption is proved to be the predominant mechanism causing the observed optical limiting behavior.
SMALL SIGNAL ANALYSIS OF WAVELENGTH CONVERSION IN SEMICONDUCTOR LASER AMPLIFIERS BASED ON GAIN SATURATION
SUN JUN-QIANG, HUANG DE-XIU, YI HE-QING
1997, 46 (12): 2369-2375. doi: 10.7498/aps.46.2369
Abstract +
Wavelength conversion due to gain saturation in a semiconductor laser amplifier(SLA) is theoretically analyzed and also-studied experimentally based on small signal model.An analytic expression is developed describing the relationship between-conversion efficiency and characteristic parameters of SLA. The numerical simulation results show that the frequency response of the converter is not only limited to the carrier lifetime, but also affected by the saturation power, gain and waveguide internal loss of SLA.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
NUMERICAL STUDY OF ION TRANSPORT IN ECR MICROWAVE PLASMA WITH A CYLINDER MODEL
GONG YE, WEN XIAO-JUN, ZHANG PENG-YUN, DENG XIN-LU
1997, 46 (12): 2376-2383. doi: 10.7498/aps.46.2376
Abstract +
In this paper,we use the Monte Carlo method to simulate the complete course,in which the ions pass through the neutral,sheath,and the shield regions of a virtual cathode formed by the secondary electrons near the workpiece surface,and finally are absorbed by the surface of the workpiece with negative bias in ECR microwave plasma.The nonlinear cylinder Poisson equations is solved successfully with “trial” method,and the smoothed and self limits spectrum of potential and distributions of energy and angle at the surface of workpiece are obtained.The magnetic filed,gas pressure and secondary effects on the potential of sheath are also discussed.
A NEW TYPE ACCELERATOR
ZENG GUI-HUA, XU ZHI-ZHAN
1997, 46 (12): 2384-2388. doi: 10.7498/aps.46.2384
Abstract +
A new type of accelerator scheme is proposed, which employs the combination of an intense laser field and a self-generated magnetic field. Theoretical analyses and numerical evalutions are performed.Results show that an electron injected can be efficiently accelerated in the combined field under the cyclotron resonance condition.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
A METHOD FOR CALCULATING THE FORM SCATTERING FUNCTION OF NONSPHERICAL PARTICLE
XU MAN-HUA, WEI MING-JIAN
1997, 46 (12): 2389-2393. doi: 10.7498/aps.46.2389
Abstract +
In measuring the particle-size distribution by small angle X-ray scattering the particle form must be known.In general the form of particles considered to be spherical ,but in practice, the form of particles was very complexity.We statistcally separate the forms of particles into sphere-like; flat-like and rod-like ones. The general method for calculating the form scattering function has been given, and we have calculated the form scattering function for sphere-like particles, and given an adjustable parameter δ that can be used in general analysis.
MEASUREMENT ON THE THERMO OPTIC COEFFICIENT dn/dT OF SEMICONDUCTOR PbS NANOPARTICLES AND THE STUDY ON THEIR OPTICAL LIMITING EFFECTS
YU BAO-LONG, ZHU CONG-SHAN, GAN FU-XI
1997, 46 (12): 2394-2400. doi: 10.7498/aps.46.2394
Abstract +
We have measured the thermo-optic coefficient dn/dT and the thermal-induced index of refraction n2 of PbS nanoparticles in organosol with the single beam Z-scan technique. The optical limiting properties of PbS nanoparticles were studied under continuous wave laser illumination. Finally, the results obtained were analyzed and discussed.
A NEW METHOD FOR CALCULATING BIT ERROR PROBABILITY IN OPTICAL SOLITON COMMUNICATION SYSTEM
HUANG HU-QING, LI FEI
1997, 46 (12): 2401-2407. doi: 10.7498/aps.46.2401
Abstract +
In this paper we use the method of steepest descent (also called saddlepoint method) to evaluate bit-error probability of the ultra-long distance optical soliton communication systems with lumped amplifiers and then compare these results with the Gaussian approximation.
NONLINEAR INTERNAL FRICTION BEHAVIOR IN MnCu ALLOY DURING THERMOELASTIC MARTENSITIC TRANSITION
LIU JUN-MIN
1997, 46 (12): 2408-2417. doi: 10.7498/aps.46.2408
Abstract +
With forced-mode measurements,the dependence of internal friction on the rate of change of temperature and vibration frequency in MnCu alloy undergoing thermoelastic martensitic phase-transition was investigated.Based on the results of the experiment a new empirical relationship was proposed-.
A MOLECULAR DYNAMICS STUDY OF SELF-DIFFUSION ON Ag(100) SURFACE
ZHUANG JUN, LIU LEI
1997, 46 (12): 2418-2425. doi: 10.7498/aps.46.2418
Abstract +
Self-diffusion of Ag/Ag (100) is investigated by molecular dynamics with the semiempirical surface-embedded-atom method (SEAM) potential. Many diffusion mechanisms, such as hopping, simple exchange, complicated exchange and a new mechanism named multiple-hopping are observed. Another model for explaining the complicated exchange mechanism is given. From Arrhenius- behavior of the adatom and the statistical results, we obtain the active energies for simple- exchange and hopping mechanisms respectively, they are 0.39 and 0.47eV.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
COHESIVE ENERGIES AND ELECTRONIC STRUCTURES OF Co3Ti AND CoTi
DUAN SU-QING, LIU SHAO-JUN, MA BEN-KUN
1997, 46 (12): 2426-2430. doi: 10.7498/aps.46.2426
Abstract +
Electronic structure calculations using the tight-binding linear muffin-tin orbital (TB-LMTO) method have been performed for two cobalt titanides, viz. Co3Ti and CoTi. The ab initio curves of cohesive energies vs lattice constants and density of states(DOS) have been obtained. The lattice constants and bulk moduli are in good agreement with the experimental values.
VORTEX MOTION AND THE HALL EFFECT IN HIGH TEMPERATURE SUPERCONDUCTORS——A TIME DEPENDANT GINZBURG LANDAU THEORY APPROACH
JIANG WEN-ZHI, LIANG FANG-YING
1997, 46 (12): 2431-2441. doi: 10.7498/aps.46.2431
Abstract +
Vortex motion in high-temperature superconductors is studied starting from a variant of the time-dependent Ginzberg-Landau(TDGL) equations,in which the order-parameter relaxation time is taken to be complex.Using Lawrence-Doniach model and considering a TDGL model modified to take into account the Hall- effect,-we have evaluated and discussed the sign change of the Hall angle and anomalous Hall effect.The results are discussed in light of rather puzzling sign change of the Hall effect which has been observed in the mixed state of the high-temperature Superconductors.
M?SSBAUER SPECTROSCOPY STUDY OF NiFe2O4 NANOSOLID COMPACTED UNDER HIGH PRESSURE
ZHENG FAN-LEI, XU DA-PENG, SU WEN-HUI, SUI YU
1997, 46 (12): 2442-2453. doi: 10.7498/aps.46.2442
Abstract +
NiFe2O4 nanoparticles with on average grain size of 12nm were compacted into nanosolids under the pressure of 0.0—4.5GPa.The M?ssbauer spectra of NiFe2O4 nanosolids at room temperature and low temperatures show that high pressure has a strong influence on the magnetic interaction and interface atomic state inside the nanosolid,though the crystal structure and average grain size of nanosolid do not change under high pressure.Under high pressure,the superparamagnetic relaxation of NiFe2O4 nanosolid is suppressed obviously by the enhancement of the interparticle magnetic dipole interaction and the superexchange interaction among the interface ions in the nanosolid,and the magnetic anisotropy of it is also weakened by the interparticle magnetic coupling in it.At the same time,the symmetry and the degree of short-range order of the polyhedrons are raised gradually with the increase of pressure,and then the atomic structure in the surface and interface zone of NiFe2O4 nanosolid shows a tendency to change into the grain boundary structure of common polycrystalline solid with large grain size.
ENERGY TRANSFER AND UPCONVERSION IN Tm3+ AND Yb3+ CODOPED ZBLAN GLASS
FENG YAN, CHEN XIAO-BO, HAO ZHAO, ZHANG GUANG-YIN, SONG FENG, LI MEI-XIAN
1997, 46 (12): 2454-2460. doi: 10.7498/aps.46.2454
Abstract +
Under the pumping of a 970nm diode laser the Tm3+ and Yb3+ codoped ZBLAN glass emits strong blue and red upconverted light.The luminescence of 1G4 and 3F4 levels results from the conse-quential Yb3+ to Tm3+ energy transfer,whereas the 1D2 level is excited by a further cross energy transfer among Tm3+ ions.The cross-relaxations of Tm3+ ions and back energy transfer of Tm3+ to Yb3+ was also observed.Furthermore,after an investigation of the special characteristic of Tm3+ and Yb3+ codoped system we think that this system is advantageous to the improvement of the net efficiency of upconversion luminesce.