Vol. 46, No. 12 (1997)
1997, 46 (12): 2289-2293. doi: 10.7498/aps.46.2289
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
1997, 46 (12): 2294-2299. doi: 10.7498/aps.46.2294
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
1997, 46 (12): 2300-2304. doi: 10.7498/aps.46.2300
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.
1997, 46 (12): 2305-2312. doi: 10.7498/aps.46.2305
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
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.
1997, 46 (12): 2320-2324. doi: 10.7498/aps.46.2320
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
1997, 46 (12): 2325-2329. doi: 10.7498/aps.46.2325
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.
1997, 46 (12): 2330-2343. doi: 10.7498/aps.46.2330
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.
1997, 46 (12): 2344-2347. doi: 10.7498/aps.46.2344
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.
1997, 46 (12): 2348-2358. doi: 10.7498/aps.46.2348
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
1997, 46 (12): 2359-2362. doi: 10.7498/aps.46.2359
Small amplitude soliton solutions are obtained which satisfy the coupled nonlinear Schr?dinger equations governing optical pulses propagation in the birefringence optical fiber.
1997, 46 (12): 2363-2368. doi: 10.7498/aps.46.2363
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
1997, 46 (12): 2369-2375. doi: 10.7498/aps.46.2369
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
1997, 46 (12): 2376-2383. doi: 10.7498/aps.46.2376
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 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
1997, 46 (12): 2389-2393. doi: 10.7498/aps.46.2389
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
1997, 46 (12): 2394-2400. doi: 10.7498/aps.46.2394
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.
1997, 46 (12): 2401-2407. doi: 10.7498/aps.46.2401
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.
1997, 46 (12): 2408-2417. doi: 10.7498/aps.46.2408
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-.
1997, 46 (12): 2418-2425. doi: 10.7498/aps.46.2418
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
1997, 46 (12): 2426-2430. doi: 10.7498/aps.46.2426
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
1997, 46 (12): 2431-2441. doi: 10.7498/aps.46.2431
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.
1997, 46 (12): 2442-2453. doi: 10.7498/aps.46.2442
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.
1997, 46 (12): 2454-2460. doi: 10.7498/aps.46.2454
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