Vol. 43, No. 4 (1994)
1994-02-20
GENERAL
1994, 43 (4): 521-529.
doi: 10.7498/aps.43.521
Abstract +
The nonlinear theory of interaction between light and matter has been established by using q-oscillator as a model for the light field. The formal solution of Schr?di-ngar equation is obtained, and the first crder approximation of emission and absorption probability are acquired by perturbation theory. We also discussed the Rabi problem for resonance condition. When q→1, the theory reduces to the common linear theory.
1994, 43 (4): 530-539.
doi: 10.7498/aps.43.530
Abstract +
The sheet resistance of square microareas with an area of 100 × 100μm2 can be determined by using a modified Van der Pauw's method. In this method, the tip positions of the four probes are controlled respectivly at the four corners out side the inner tangential circle of square microareas by direct inspection using a microscope with a magnification of 8 × 10. The measurement results are independent of wanderings of probes and it is not necessary to determine the precise positions of probes in order to make corrections for the boundary effect. These conclusions are proved in this paper by using FEM and have been confirmed by the determination of sheet resistance of gold microbumps.
NUCLEAR PHYSICS
1994, 43 (4): 540-546.
doi: 10.7498/aps.43.540
Abstract +
We define explicitly a fission path from u single sphere to partial overlapping up to separated spheres to describe three fragments with 120° (oblate), along a line (prolate), and to describe cascade with the first asysinetric fission and the second sysmetric fission. It is easy to compare the three modes for one deformation parameter. The barrieres are calculated by the temperature dependence of liquid drop model, adding the proximity potential to take into account the finite range effects of the nuclear force in a crevice, adding shell energy which is local shell effect interyra-ting all over the surface, and the fission probabilities are calculated, which lead to qualitative understanding for the best mode of ternary fission.
1994, 43 (4): 547-554.
doi: 10.7498/aps.43.547
Abstract +
This work is the first attempt to decompose the positron annihilation lifetime spectrum into the form of a frequency spectrum by Fast Fourier Transform (FFT) technique. Each real peak in the frequency spectrum indicates a lifetime component. The peak position corresponds to the annihilation constants, the peak area is proportional to the intensity of the component. The principle of this method is described in this paper. We thoughtfully consider the effects of the instrumental resolution function and the statistical error. A program is compiled with Turbo C and successfully operated on PC ALR-286. The analysis results for some simulated spectrum are satisfactory. The work indicates that the advantages of this method are its simplicity, rapidity, less effect of the instrument resolution function and no guessing what the components are before analysis.
ATOMIC AND MOLECULAR PHYSICS
1994, 43 (4): 555-559.
doi: 10.7498/aps.43.555
Abstract +
The surface fluorescence of Rhodamine B (RhB) adsorbed on colloidal silver was investigated. It was found that the 572.5 nm fluorescence band of RhB quenched sharply. However, at the same time the enhancement factor of the other fluorescence band of RhB at 530.0 nm was up to 60 when Ag sol was added.The time-effect fluorescence spectra of RhB adsorbed on Ag surface have been observed by OMA, showing that the quenching and enhancement processes of these two bands were inversed each other at any moment of observation.
1994, 43 (4): 560-565.
doi: 10.7498/aps.43.560
Abstract +
Experimental studies of collision between electron and H2+ ions producing excited atates have been performed by OMA using the crossing beam. The Balmer α,β emission spectra have been measured. The excitation cross sections have been calculated. And the dissociative recombination has been discussed qualitatively.
1994, 43 (4): 566-569.
doi: 10.7498/aps.43.566
Abstract +
The C60/C70, sample was prepared by carbon electric arc method, and its crystal morphology was studied by optical microscopy, SEM and TEM. The results indicate that the growth of C60/C70 crystal obeys the rule of faceted growth, and it grows, into regular quadrilateral, pentagon and/or hexagon-like crystals finally.
CLASSICAL AREA OF PHENOMENOLOGY
1994, 43 (4): 570-579.
doi: 10.7498/aps.43.570
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In this paper, the entropy properties of the field in the two-photon Jaynes-Cu-mmings model with an additional Kerr medium are studied, the effect of nonlineari-ty interaction of the Kerr medium with the model field on the field entropy are discussed. With the help of quantum interference in phase space between two part of the bifurcation of the Q function of the field, the physical mechanism of properties of the field entropy are explained.
1994, 43 (4): 580-590.
doi: 10.7498/aps.43.580
Abstract +
A semiconductor laser is driven by a electrical circuit of gain switch, the variations of its pulse width and power vs bias current and driving pulse are studied. The optimal parameters are found. The shortest pulse width of this semiconductor laser is 26 ps. Also, using analytic?! model and numerical calculation, the experimental results are simulated successfully.
1994, 43 (4): 591-596.
doi: 10.7498/aps.43.591
Abstract +
The general propagating solitary wave solution in semiconductor-doped glass fibers, in which the nonlinearity is of saturation-type, is given. The properties of the solitary waves in various cases are discussed and the formation conditions of the bright and dark solitons are analzed.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
1994, 43 (4): 597-603.
doi: 10.7498/aps.43.597
Abstract +
Experimental results on plasma instability and potential confinement configuration in MM-4U tandem mirror are presented. The measured axial potential profile shows that the axisymmetric negative plasma potential tandem mirror confinement configuration has been established; the obtained plasma density profile is similar to the potential profile. The relationships between the plasma parameters and the eng-neering parameters have also been studied prelimilarily. The low frequency instability was observed at low plasma density in the central cell. By means of the linear spectral analysis techniques, the instability mode has been determined. It is suggested that the instability is excited in the low density plasma when the electron beam drift velocities exceed the ion acoustic speed.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1994, 43 (4): 604-608.
doi: 10.7498/aps.43.604
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This paper reports the anomalous infrared spectra of nanometer-sized Fe2O3 particles under certain conditions: some IR absorption peaks obviously shift, theirrelative intensities are changed; all peaks are remarkably broadened; and a broadbackground-absorption band appears. It is suggested that these anomalous IR chac-teristics indicate thata structural phase transition occurs, which results from the polaronic effect due to the increasing of electron-phonon coupling. This effect not only contains the contribution of LO phonons, but also the contribution of softmodes produced by interfacial atoms or molecules.
1994, 43 (4): 609-615.
doi: 10.7498/aps.43.609
Abstract +
Molecular dynamics simulations were performed to obtain the two-dimensional pair correlation functions of Si(001) surface and deeper layers. The atoms interact via a potential developed by Stillinger and Weber, which includes both two-body and three-body contributions. The results show that the atoms in deeper layers still remain at their(001) atomic plane lattice sites, while the atoms in surface layer are rearranged, and a large part of them form bonding and the bond length is 0.2, 40nm. The relaxation problems have also been discussed.
1994, 43 (4): 616-621.
doi: 10.7498/aps.43.616
Abstract +
This report presents the results on the investigation of the effect of ricionoleic acid on the structures of the liquid crystal state of mixed phospholipid-cholesterol liposomes by means of the Small Angle X-ray Scattering (SAXS) and 31P Nuclear Magnetism Resomance(31P-NMR). The study shows that the ricinoleic acid helps to stabilize the structure of the mixed phospholipid-cholesterol liposomes and that the polyphase liposome with ricinoleic acid prepared from phosphoric buffer solution containing polyvinylpyrrolidone (PVP) is in the cubic-hexagonal phase.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1994, 43 (4): 622-626.
doi: 10.7498/aps.43.622
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In this paper the electronic densities of states(DOS) of Nb bulk, local densities of states (LDOS) of clean Nb(100) surface and surface energies relative to the bulk have been calculated by using LMTO method. The DOS of bulk Nb calculated in this paper is in agreement well with other method, the calculated surface energies support the result of low energy electron diffraction (LEED)dynamic calculation. Moreover, after analysing the LDOS, we suggest that there are surface states for the clean Nb(100) surface, which are above the Fermi, energy level.
1994, 43 (4): 627-631.
doi: 10.7498/aps.43.627
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In this paper, we give the principle and the empirical formulas of the preparation for nanometer sized a-Si3N4 particles by laser induced chemical vapor deposition (LICVD). Under certain technological parameters, our experiments have obtained high quality nanometer a-Si3N4 particles whose average diameter is 6.5nm. We disperse these particles in organic solvent so as to study its energy level structure with ultravolet-visible spectrum. The photoluminescent experiments show its peak-like spectrum structure and the splitting of energy band, which relate to super micro-particles. We also describe the picture of the physical structure of nanometer a-Si3N4 particles and demonstrate that silicon"wrong bond"≡Si-Si≡and silicon dangling bond≡Si30 play a dominant role in the spectrum character for Si-riched nanometer a-Si3N4 particle.
1994, 43 (4): 632-636.
doi: 10.7498/aps.43.632
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In this paper, low frequency voltage noise property in impurity-doped blue bronzes is investigated. It is found that these low frequency voltage noise can be strongly enhanced by impurities or defects, for which the amplitude and shape of the oscillations are closely related to the initial conducting current of sample during cooling. The results indicate that the origin of the broad-band noise in charge-density-wave system may result from the macroscopic defects or impurities.
1994, 43 (4): 637-645.
doi: 10.7498/aps.43.637
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In this work, the ground state zero-field spitting of the tetragonal symmetry in KZnF3:Cr3+ has been studied using the Newman superposition model. The existence of Zn2+ -vacancy and the crystal lattice distortion has been verified. It is found that the contribution from the Zn2+-vacancy are non-negligible. Meanwhile, we obtain that the F- ion along [001] axis moves towards the central Cr3+ ion by Δ = 0.0029-0.0043nm. It has been verified also that the tetragonal center with D = - 0.2167cm-1 in KMgF3:Cr3+ is a CrOF5 cluster. To get agreement with the EPR experiment data it is necessary to introduce a contraction of the four fluorine ions in the plane perpendicular to the Cr3+-O2- axies pair, at the same time, the Cr3+ moves towards the O2- and the O2- moves towards the Cr3+ ion, but the displacement of the Cr3+ is larger than that O2- in CrOF5 cluster.
1994, 43 (4): 646-650.
doi: 10.7498/aps.43.646
Abstract +
The photoluminescence (PL) intensity of porous silicon in H2O2 under illtimina-tion increases first, and then decreases with increasing processing time, and the PL intensity reaches its maximum when the processing time is one minute. Under illumination in air, the PL degradation of porous silicon without processing is substa-ntia1, but that for the processed porous silicon gets much smaller. The Fourier-transform infrared (FTIR) absorption shows that the localized vibration related to oxygen increases greatly but all kinds of Si-H bonds decrease obviously. Contrasting the variation of the FTIR with that of the PL in the processes, we conclude that the luminescence does not come from the Si-H bonds on the surfaces of porous silicon.
AC CHARACTERISTICS OF A THIN Ag FILM PERCOLATION SYSTEM DEPOSITED ON A STATISTICAL FRACTAL SUBSTRATE
1994, 43 (4): 651-654.
doi: 10.7498/aps.43.651
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Ac characteristics of a thin Ag film percolation system deposited on a broken surface of α-Al2O3 ceramics are measured. We prove that the ac conductivity and ac dielectric constant obey the power law and the general scaling relation near the percolation threshold. The ac capacitance data as a function of the dc resistivity are obtained and its role is discussed.
1994, 43 (4): 655-659.
doi: 10.7498/aps.43.655
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According to the changes of XPS, IR and lattice constants in bismuth (lead) system superconductor, the location of F substitution in O(2) has been determined. The Tc0 in fluorme doped bismuth (lead) system superconductor can be inproved greatly with the formation of Pb-F and Cu-F, the strengthening of coherence between Cu-O and Bi-O plane, and the increasing of chemical pressure and the density of electronic states.
1994, 43 (4): 660-666.
doi: 10.7498/aps.43.660
Abstract +
By using D. C. magnetron sputtering and selecting the total gas pressure 80 Pa, the deposition time 60 min and the target size 80, four amorphous YBCO/Al2O3 films were prepared with varying parameters, such as magnetic intensity, distance from the target to the substrate, and partial pressure ratio Ar/O2. The Ba and Cu concentrations relative to Y and the film thickness versus substrate position in the four samples were analyzed by Rutherford backscattering (RBS). Results have showed that the relative concentation of barium and copper were quite different at different positions and the film thickness were not uniform under disparate deposition conditions. However, one of the samples has an almost even profile in a region of 17mm around the center of the sample, where the film thickness is approximately equal to 0.13μm and the Y, Ba. Cu ratios are close to 1:2:3.
1994, 43 (4): 667-672.
doi: 10.7498/aps.43.667
Abstract +
Based on experimental data, the photo-induced structural change is interpreted as condensation of triple exciton polarons. The excitonic envelop functions for sin-glet and triplet state are calculated numerically. A possible mechanism of photo-induced structural change is presented and dicussed in detail.
1994, 43 (4): 673-677.
doi: 10.7498/aps.43.673
Abstract +
AlxGa1-xAs Auger sensitivity factors have been determined by using PHI 610 scanning Auger microprobe with pure elemental standards Al, Ag and matrix GaAs. The quantitative results of AlxGa1-xAs measured by the present method are in very good agreement with that by X-ray double crystal measurement. It is shown that by using sensitivity factors obtained from the self-instrument, the accuracy of the quantitative AES analysis can be considerably improved compared with that using elemental relative sensitivity factors given by the PHI handbook or internal standard method.
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
1994, 43 (4): 678-682.
doi: 10.7498/aps.43.678
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In this paper, the experimental procedures are presented for laser cladding WC-TiN-SiC-Co high hard alloy of the carbon steel surface using a CO2 laser with am output power of 2kW. We also give a comprehensive analysis about the phase structure, the phase morphology, the distribution profile of the hardness and the resistance to abrassion of the sample after treatment. The experimental results indicate-that the mechanical properties and the chemical composition in the surface layer of material will basically changed. Furthermore, a preliminary discussion of the strengthening mechanism of high hard alloy formed by laser cladding is alto given.
GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS
1994, 43 (4): 683-688.
doi: 10.7498/aps.43.683
Abstract +
An approximate expression of the diffuse reflectance just beneath the sea surface is developed theoretically by analytical way which is essentially consistent with the results of numerical methods
