Vol. 46, No. 11 (1997)
1997-06-05
GENERAL
1997, 46 (11): 2080-2094.
doi: 10.7498/aps.46.2080
Abstract +
Based on the construction theorem of quantum invariant,the results of Lewis and Riesenfeld are rededuced in a much simpler way and extended significantly.Meanwhile,it is pointed out that the Lewis Riesenfeld phases are in general not of physical meaning unless the invariants take specific forms which have been worked out.As an example,the spin system in a magnetic field is discussed in detail.
1997, 46 (11): 2095-2103.
doi: 10.7498/aps.46.2095
Abstract +
Generally,dynamical analyses of the original systems are limited to some extent by the observational methods.In this paper,by using the method of multivariate singular systems analysis (M SSA),which combines simultaneously information sampling the complete range of the spatial cross correlation function in signals with complex spatio temporal structure,we study the changes of the correlation dimensions and the largest Lyapunov exponents of the multivariate time series in an- observation window.And the characterization of prediction is discussed also with the multi-layer- perceptron.It is shown that when the number of the variates is increased,the complexity is also-- increased and the stability and the characterization of prediction are different.
ATOMIC AND MOLECULAR PHYSICS
1997, 46 (11): 2104-2110.
doi: 10.7498/aps.46.2104
Abstract +
The B spline method for calculating the correlation energy of helium atoms is proposed.The result is compared with that by Slater basis functions.The virtue defect and practicability of B spline technique are analysed.It is shown that the B spline technique can be used widely in the calculation of electronic interaction.
1997, 46 (11): 2111-2116.
doi: 10.7498/aps.46.2111
Abstract +
In hollow cathode discharge laser induced fluorescence experiment,when a strong external magnetic field is applied in the direction of observation and “magic angle” excitation method is adopted,to ArI5p[3/2]2,we find that the stronger the magnetic field,the faster the collision depopulation rates,but the slower the collision disalignment rates.On the whole,the decay rates of the curves become slower with the increase of the magnetic field strength.The natural lifetime of ArI5p[3/2]2 was measured to be 120±5ns under the condition without an external magnetic field.
1997, 46 (11): 2117-2123.
doi: 10.7498/aps.46.2117
Abstract +
Interaction between the detecting field and the ion cloud in an actual Paul trap is described by the Duffing equation.For small damping,the unstable periodic solutions embedded in chaotic attractor and their stability conditions are obtained.Theoretical analysis reveals that the instability of chaotic motion can be controlled by adjusting the control parameters to fit the conditions.Excellent agreement is found between the analytical results and experimental data.
1997, 46 (11): 2124-2129.
doi: 10.7498/aps.46.2124
Abstract +
From the nuclear Schrdinger equation of a diatomic molecule with the vibration rotational interaction term,we derive a wave function which is related not only with vibrational quantum number,but also with rotational one.The Franck Condon factors of the two band systems A1Π→X1Σ+ and b3Σ+→a3Π of BF are calculated by use of the derived wave function with the rotational quantum number ranging from J=0 to J=200.The results obtained can be used in the cases under low or high temperature condition,and also that under the condition of strong shock wave.
1997, 46 (11): 2130-2137.
doi: 10.7498/aps.46.2130
Abstract +
Surface enhanced Raman scattering (SERS) of halate ions in silver colloids is studied by near infrared (NIR) laser excitation.Ions of ClO－3 and BrO－3 in silver colloids give rise to SERS bands at about 226 and 158cm－1,respectively while IO－3 ions on colloidal silver surface result in two Raman bands at about 750 and 334cm－1.These results indicate that the interactions of ClO－3 and BrO－3 ions with silver surface are through their lone pair electrons of Cl and Br.Nevertherless,IO－3 ions bond to silver surface through their negatively charged O－.The interaction strength of halate ions with silver are measured to be BrO－3>ClO－3≈IO－3.The enhancements of the Raman modes of pyridine caused by addition of halate ions increase in the order ClO－3－3－3.The enhancement mechanisms in NIR SERS are discussed.
1997, 46 (11): 2138-2145.
doi: 10.7498/aps.46.2138
Abstract +
The predissociation of H 2 in its Rydberg states has been studied using the multichannel quantum defect theory,combined with the frame transformation and the non iterative eigenchannel R matrix method.The predissociation line positions and the widths are calculated for 3pπ 1πu+(v=3,J=1,2) and 4pσ B″1Σu+(v=2,J=1,2) levels.The predissociation mechanisms are discussed.
1997, 46 (11): 2146-2153.
doi: 10.7498/aps.46.2146
Abstract +
In this paper,dielectronic recombination process is proposed as two independent processes resonant capture(inverse Auger) process and radiative decay process,which can be used- conveniently in the varied plasmas environments.Through the quantum defect theory,a simplified- analytical formula is introduced to calculate the Auger rate and the theoretical results have been- compared with a simplified relativistical configuration interaction calculation.Finally,a method for- applying the formula to the average atom model is given.
CLASSICAL AREA OF PHENOMENOLOGY
1997, 46 (11): 2154-2159.
doi: 10.7498/aps.46.2154
Abstract +
An analytic expression have been obtained by using asymptotic approximations to the type of integral expression that frequently occurs in near field optics.By using the expression,the image degradation and some factors repressurized by imaging system of the near field optics are interpreted respectively.Furthermore,an expression of the degrees of freedom of scanning near field optical microscopy is given.Also the relation between the resolution and the degrees of freedom in the scanning image system of near field optics is analyzed.
1997, 46 (11): 2160-2165.
doi: 10.7498/aps.46.2160
Abstract +
In this paper, a new approach of exact solution of Jaynes-Cummings model under rotationless wave approximation is proposed. The Jaynes-Cummings models of two-level system and three-level system have been investigated. Compared to some other approximate approaches, this approach can give not only an analytic exact solution, which agrees with others results but also a restraint condition, which is usefull for practical experiment.
1997, 46 (11): 2166-2173.
doi: 10.7498/aps.46.2166
Abstract +
Soliton solutions and the properties of a class of generalized nonlinear Schr?dinger (GNLS) equations in N-space are discussed analytically and numerically. The discussion has been done by using a travelling wave method to get one soliton solution and the finite difference method to get the numerical solutions for the GNLS equations. The states of the soliton solutions of the system admitting nonlinearity have been investigated when α→0 and α→∞.The P-R scheme for the system has been studied, and the conditions of stability and convergence for the scheme were obtained.
1997, 46 (11): 2174-2179.
doi: 10.7498/aps.46.2174
Abstract +
We study the chirp characteristics of femtosecond laser pulse propagating in conjugated polymer with larger nonlinear dispersion effect by means of theoretical and simulated methods. From the chirp characteristics of femtosecond laser pulse, the explanation for effective spectrum broadening and self-frequency-shift is given.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
1997, 46 (11): 2180-2187.
doi: 10.7498/aps.46.2180
Abstract +
In this paper, a physical description of the mechanism of microwave generation in Super-Reltron is presented, and the analytical formulas of the beam bunching in the modulation cavity and the prebunching beam emitted in the radiation cavity are derived.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1997, 46 (11): 2188-2197.
doi: 10.7498/aps.46.2188
Abstract +
The direction of the energy flow in perfect crystals near the atomic absorption edge is studied in detail in the symmetrical Laue and Bragg cases. It is found that in the symmetrical Laue case, the direction of the energy flow corresponding to a tie point on the dispersion surface deviates from the normal of the real part of the dispersion surface, only when the contribution of the imaginary part of the atomic scattering factor to the diffraction is comparable to that of the real part. However, in the symmetrical Bragg case, the deviation takes place in the so-called “total reflection” region even when the contribution of the imaginary part of the atomic scattering factor to the diffraction is negligible. When diffraction is induced only by the imaginary part of the atomic scattering factor, the deviation becomes the largest in the Laue case, but the least in the Bragg case.
1997, 46 (11): 2198-2205.
doi: 10.7498/aps.46.2198
Abstract +
The multilayer relaxation of Al(100),(110),(111) and (210),(211),(310),(311) and (331) surfaces is calculated using the modified embedded atom method. The results are in good agreement with the experimental data and first-principle calculations. Especially, the results for Al(100) and (111), which show “anomalous” behaviors in surface relaxation, that is both exhibit- expansions between the first two layers, are consistent with the experimental data. It is suggested- that these expansions are mainly due to the increase of electronic s state and the decrease of p state in the bonds between the first two layers.
1997, 46 (11): 2206-2214.
doi: 10.7498/aps.46.2206
Abstract +
In this paper, textured (100) diamond films are successfully grown on single crystalline (100) silicon substrate by bias enhanced hot filament chemical vapor deposition from a gas mixture of methane and hydrogen. The films show the well defined facet and are identified to be textured films by means of scanning electron microscopy, Raman spectroscopy and X-ray diffraction analysis. The effects of various parameters have been systematically investigated and the optimum conditions of films growth have been obtained.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1997, 46 (11): 2215-2222.
doi: 10.7498/aps.46.2215
Abstract +
Static electron transport in the material 3C-SiC is analyzed by using single particle Monte Carlo method at high field and high temperature. The physical model used in the simulation is developed by considering the energy gap structures and the main scattering mechanisms in details. The results show the excellent high field and high temperature properties of the material. The scattering mechanisms at high temperature and high field are discussed by analysing the results.
1997, 46 (11): 2223-2232.
doi: 10.7498/aps.46.2223
Abstract +
We introduced a new technique called “Transient Thermoelectric Effect (TTE)”, which was based on carrier-diffusion as irradiated by a pulsed laser. The observed TTE voltages decayed exponentially with time, showing a multi-relaxation process with characteristic relaxation times τi(i=1,2,3,…) for thermal diffusions of photo-induced conduction carriers, analyses of these results could give valuable information about carrier mobilities, effective masses and Fermi surfaces. The principle and the main analysis method were also described in detail.
1997, 46 (11): 2233-2240.
doi: 10.7498/aps.46.2233
Abstract +
The dynamic behaviors of supercurrent in mesoscopic Josephson junction in the presence of a dc bias voltage V0-and of correlated two-mode SU(1,1) coherent states of quantum electromagnetic field, as well as current-voltage steps and Shapiro dc current, are investigated.It is shown that the time evolution of supercurrent exhibits collapse and revival phenomenon, but for non-correlated two-mode coherent states it does not exhibit such a phenomenon. And the current-voltage steps of correlated two-mode SU(1,1) coherent states of quantum electromagnetic field are different from that of classical electromagnetic field and that of non correlated two-mode coherent states.
1997, 46 (11): 2241-2249.
doi: 10.7498/aps.46.2241
Abstract +
The compounds of Gd2（Fe1-xCox）15Ga2(0≤x≤1.0) and Gd2（Fe0.8Co0.2）17-yGay(0≤y≤8) were prepared by arc melting. Their structure and magnetic properties have been studied by means of X ray diffraction and magnetic measurements. Experimental results show that single phase compounds with the 2∶17-type structure were obtained for all samples. It was found that the unit cell volume of Gd2（Fe1-xCox）15Ga2 compounds decreases, while the Curie temperature Tc increases monotonously with increasing Co concentration. The saturation magnetization Ms at 1.5K first increases with increasing x, then decreases, showing a value of maximum at x=0.2. For Gd2（Fe0.8Co0.2）17-yGay,the unit cell volume increases, the Curie temperature and the saturation magnetization at 1.5K decrease monotonously with increasing Ga content. The substitution of Co or Ga for Fe in Gd2Fe17 compounds results in a change of magnetocrystalline anisotropy of Fe or Co sublattice from easy plane to easy c-axis at room temperature. This is likely related to the preferential site occupancy of Ga atom.
1997, 46 (11): 2250-2257.
doi: 10.7498/aps.46.2250
Abstract +
Some Fe-Si alloys have been prepared using the mechanical alloying method. The structure of the obtained Fe-Si alloys is the same as that of the bcc α-Fe. The final powders mainly consist of some particles with a grain size from a few hundreds of nanometers to several microns,while these particles are composed of some subgrains with a microcrystalline size of about 15—20 nanometers. Their magnetic properties have also been investigated. The values of their specific saturation magnetization (σs) are slightly less than those of the corresponding single crystalline and polycrystalline Fe-Si alloys, while the values of their coercive force (Hc) are nuch higher than those of corresponding Fe-Si alloys in bulk. Their magnetic spectra are all relaxation type except for Fe75Si25, and the values of their μ′ and μ″ are comparable with those of the ferrite composite materials and, in their magnetizing process, the domain wall displacements are predominant.
1997, 46 (11): 2258-2266.
doi: 10.7498/aps.46.2258
Abstract +
This paper discussed a method of designing soft X-ray multilayers for shorter wavelengths and showed that a difference between the designing of longer wavelength soft X-ray multilayers and that of the shorter one.For the latter,the minimum continuous thickness of the metal layer have to be considered.The method of second order designing could be a way to deposit high-quality multilayer mirrors for shorter wavelengths.The measured reflectivity of a Mo/Si multilayer for 4.47nm is also reported.
1997, 46 (11): 2267-2273.
doi: 10.7498/aps.46.2267
Abstract +
The structures of NaY and ultrastability Y-type (USY) zeolite were studied by positron lifetime spectroscopy.Four lifetimes could be obtained in NaY zeolite,the two larger components were assigned to be o-Ps annihilation in the β cage and supercage respectively.In USY zeolite,however,an additional lifetime component τ5 was observed,which was about 92ns in vacuum with continuous distribution from 39ns to 142ns by the Laplace inversion analysis of lifetime spectrum.The second larger lifetimes τ4 also increased to 14ns,compared to that in NaY zeolite.Existence of the longer lifetimes τ4 and τ5 is due to the porous structure of USY.The positron lifetime in USY zeolite was also measured as a function of air pressure ranging from 0 (vacuum) to 0.1MPa.The most interesting was the variation of the largest components τ5 and I5.They both decreased with increasing air pressure.The results can be explained as follows.First,the oxygen contained in the air could quench the Ps and reduce its lifetime and intensity.Second,the increasing density of air could also increase the probability of o-Ps pick-off annihilation and reduce its formation.These would lead to the decrease of its lifetime and intensity.
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
1997, 46 (11): 2274-2279.
doi: 10.7498/aps.46.2274
Abstract +
Buried SiC layers were formed by using a metal vapor vacuum arc (MEVVA) ion source,with C＋ ions implanted into Si substrates under different doses.In the present study, the extracted voltage was 50kV and the ion dose was varied from 3.0×1017—1.6×1018cｍ-2.According to infrared absorption measurements,it was found that the structure of the buried SiC layers depended on the ion dose.Moreover,the results also demonstrated that the buried SiC layers including cubic crystalline SiC could be synthesized at an averaged substrate temperature of lower than 400℃ with the MEVVA ion source.
GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS
1997, 46 (11): 2280-2288.
doi: 10.7498/aps.46.2280
Abstract +
The exact locations of the universe horizon and the outer and inner horizons of the black hole are given in the Vaidya-Bonner-de Sitter space-time.Hawking radiation of charged Dirac particles near the outer horizon and the universe horizon are studied.It is determined that any two of the three horizons cannot coincide.
