Vol. 45, No. 9 (1996)
1996-05-05
GENERAL
1996, 45 (9): 1425-1429.
doi: 10.7498/aps.45.1425
Abstract +
Using a one-dimensional damped and parametrically driven diatomic nonlinear coupled pendulum lattice ,we find for the first time in the macro-experiment that the amplitude of localized soliton is stable, quasiperiodic, periodic or random depending on the driven parameter. Theoretically, these experimental results can be explained by the solution of a quintic nonlinear Schr?dinger equation.
1996, 45 (9): 1430-1437.
doi: 10.7498/aps.45.1430
Abstract +
The free carrier absorption spectra for Hg1-xCdxTe epilayers are derived by considering the composition-in-depth nonuniformity and Te precipitates in the epilayers. The results show that the absorption behaviour of epilayers exhibits many differences with that of the bulk materials. The Te precipitates may exist when the calculated transmission is much higher than the experimental data.
NUCLEAR PHYSICS
1996, 45 (9): 1438-1443.
doi: 10.7498/aps.45.1438
Abstract +
The in-plane and out-of-plane emission of unstable light nuclei was measured in the reaction of ４０Ａｒ＋１９７Ａｕ at energy 25MeV/u by means of extensive particle-particle correlation. An in-plane enhancement is observed for mid-rapidity unstable light nuclei, indicating a rotational effect exists in this reaction system. This in-plane enhanced emission becomes stronger with increasing of impact parameter, but becomes a little weaker with increasiong of energy of the excited state.
ATOMIC AND MOLECULAR PHYSICS
1996, 45 (9): 1444-1449.
doi: 10.7498/aps.45.1444
Abstract +
The excited states produced in collisions of N+2 and N+ with Ne have been studied by using emission spectroscopy. The emission spectra show that there are four processes of the excitation in these collision systems,namely:(1)Direct excitation of target;(2)Direct excitation of atomic projectile;(1)Direct excitation of molecular ion;(4)Charge exchange excitation. The emission cross sections for each spectral line are calculated . Acomparison of emission cross sections in collisions between N+2-Ne and N+-Ne is made. Some differences are found and the primary results have been discussed qualitatively.
CLASSICAL AREA OF PHENOMENOLOGY
1996, 45 (9): 1450-1456.
doi: 10.7498/aps.45.1450
Abstract +
By making a study of spectral coherence and spectrum modification induced by spectral correlation of optical field, we try to find whether it is possible to modulate a spectrum. This artical gives an example of reducing spectrum width and performs a numerical calculation. We find that the spectral coherence method can exploit much more light energy while spectrum width becomes nattow, the rate of exploiting light energy being much large than that of a filter.
1996, 45 (9): 1457-1462.
doi: 10.7498/aps.45.1457
Abstract +
Hologram is analysed from a new point of view ——the microstructures of elementary hologram. The elementary analysis theory is developped to decompose the information of thrww-dimensional scattering object recorded in hologram to that of a elementary point of the object. The mocrocoding patterns of the object information under typical recording conditions are discussed.
1996, 45 (9): 1463-1478.
doi: 10.7498/aps.45.1463
Abstract +
The symmetry between the field and atomic dipole squeezing(SFAS)has been exposed in the resonant JCM. The influence of some nonlinear interactions,including the nonresonant interaction, the virtual-photon processes,the intensity-dependent coupling and the interaction of a Kerr-like medium with the cavity on the SFAS has been discussed . At(2m+1)-quantum resonance,the relationship between the field and atomic squeezing has been examined.
1996, 45 (9): 1479-1486.
doi: 10.7498/aps.45.1479
Abstract +
By measuring the excitation spectra of the 4f5d bands and the fluorescent decays of the 5ＤJ—7Ｆ0（Ｊ＝２，１，０） transition probability depending on temperature in MyM′1-yFClxBr1-x:Sm2+(M=Mg,Ca,Sr,Ba)series, we have studied the dependence of the energy separation between the 4f5d bands and the 5ＤJ level, the 5ＤJ—7Ｆ0（Ｊ＝２，１，０） transition probability on the composition grade(x) and (y) and the effect on hole-burning efficiency. We draw conclusions as below: In MyM′1-yFClxBr1-x:Sm2+ series, the 4f5d bands will be more close to the 5ＤJ level with the increase of the Br concentration and the concentration if snakk radium alkaline earth ion, and this situation makes the 5ＤJ—7Ｆ0 electron transition probability increase. By reasoning, the hole-burning efficiency of Sm2+ are expected to by enhanced.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
1996, 45 (9): 1487-1491.
doi: 10.7498/aps.45.1487
Abstract +
The characteristics of high-order relativistic harmonic generation excited by intense laser pluse in underdense plamas is inverstigated. With quasistatic approximation, the growth and saturation of Nth-order relativistic harmonics are analyzed, and the ratio of high-order power to fundamental wave power is described and calculated.
1996, 45 (9): 1492-1500.
doi: 10.7498/aps.45.1492
Abstract +
By numerically solving the tow-dimensional time-dependent non-linear Fokker-Planck equations, the distribution functions are calculated and the D-T fusion reactivity are evaluated. For the tritium parallel injection case, the reactivity variation induced by the non-Maxwellian distribution is analyzed. It is pointed out that it is appropriate to define. The calculation resutlts show that η increases from 1 to maximum and then decreases during NBI heating. Either high input power or high beam energy can make η to decrease to a value less than 1. When η decreases to 1, Ｔ∥Ｔ is raised to about 10keV.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1996, 45 (9): 1501-1505.
doi: 10.7498/aps.45.1501
Abstract +
Porous materials silica aerogels and xerogels were obtained through a sol-gel process from TEOS. Samples derived from different preparation circumstances were investigated via small-angle X-ray scattering. The power-law dependence of the scattered intensity, a characteristic of fractal structures, was observed for all the one-step aerogels. While for the xerogels and aerogels derived from a two-step sol-gel process, the power-law dependence of the scattered intensity was not observed. The xerogels are found to consist of a number of large spherical particles which were densely packed together.
1996, 45 (9): 1506-1512.
doi: 10.7498/aps.45.1506
Abstract +
High density electropulsing and vacuum annealing treatments of amorphous alloy Ｆｅ７３Ｎｉ５Ｓｉ８Ｂ１４ have been carried out. The microstructural change and crystallization behavior after treating were investigated by M?ssbauer spectroscopy and TEM techniques. The experimental results show that the "electron wind " induced by high density current promotes the structure of amorphous alloy to be more relaxed and crystallized as compared with annealing treatment. And, The accelerating effect is further enhanced with an increase of current density.
1996, 45 (9): 1513-1520.
doi: 10.7498/aps.45.1513
Abstract +
The heat capacity Ｃpof ThO2 can be calculated as the phonon part of Ｃp for other actinide dioxides used as fuel in nuclear reactors. Precise determination of the phonon part of Ｃp of actinide dioxides is helpful to find out the contributions of other factores to Ｃp. In this paper we have, through studying the heat capacity of ThO2, developed a general method applicable to the study of Ｃp of other solids. In the developed method the three type-different experimental measurements made on a solid-heat capacity, thermal expansion and Debye-Waller factor-can be brought together for comparison. The application of this method to the study of Ｃp of ThO2 has enabled us to propose a better description of Ｃp of ThO2 than the generally accepted expression.
1996, 45 (9): 1521-1525.
doi: 10.7498/aps.45.1521
Abstract +
The interference between the light diffracted incidence surface wave and reflection surface wave is observed. The wave vector varies with propogation distance and the variation of surface phase causes the vatiation of viberation mode of liquid surface. The formulation of surface wave chromatioc dispersion is reconstructed and theoritical results of interference by reflection surface wave are derived. The surface tension of water and its variation with temperature are detected.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1996, 45 (9): 1526-1535.
doi: 10.7498/aps.45.1526
Abstract +
By using the linear muffin-tin orbital (LMTO) method, the surface electronic structure of ZnS(111) slab model is calculated, the total, local and partial densities of states for these models are presented. The structure stability and surface state are discussed. Theoretical density of states is in good agreement with the experimental result obtained from the synchrotron radiation photoemission spectra of the ZnS(111) surface.
1996, 45 (9): 1536-1542.
doi: 10.7498/aps.45.1536
Abstract +
Taking the average bond energy Em as reference level, and empitical pseudopotential scheme is employed to calculate the band alignment(including valence band, conduction band, and band gap) of three semiconductor heterojunctions:GaAs/Ge,AlAs/GaAs and AlAs/Ge and the complete and more accurate calculation results are obtained. In our calculation, the valence -band offset values ΔＥｖ of the above three heterojunctions are ０.５７，０.５０ and １.０７ｅＶ,respectively．
1996, 45 (9): 1543-1550.
doi: 10.7498/aps.45.1543
Abstract +
The quantitative analyses for our proposed potential-barrier model are given in this paper. The results quantitatively explain how the semiconductiong BaTiO3 ceramics transforms from PTC effect to GBBL capacitor. The designs of PTC resistors and GBBL capacitors from this model are made, and the design properties are much better than that of present experimental data. The mathods improving the properties of relevant devices are discussed. The model provides a theoretical basis for the design, manufacture and property improvement of semiconducting BaTiO3 ceramic devices.
1996, 45 (9): 1551-1561.
doi: 10.7498/aps.45.1551
Abstract +
An analytical method is presented for investigating the resonant behaviors of composed resonator formed by deporviting the c caxis oriented ＹＢａ2Ｃｕ3Ｏ７－δ (δ≈≈0) thin film on ＬａＡｌＯ3（００１）. The concept of the negative dielectric medium for a superconductor is introduced within the framework of the two-fluid model, which permits us to treat a superconductor as any other penetrable materials so as only its electromagnetic property is concerned. A conformal transformation is further suggested to map the original open boundary value problem to a closed one. This not only makes the original problem readily solved by using the variational technique, but also is powerful for the analyzing a kind of problems such as the propagation characteristics of the superconducting microstripe and coplannar waveguiding structures.
1996, 45 (9): 1562-1569.
doi: 10.7498/aps.45.1562
Abstract +
Growth characteristics of Bi-2212 single crystals using self-flux Bi2O3 have been experimentally studied systematically. Some of the problems encountered in the growth of crystals in the Bi system, such as the amounts of flux, thermal cycle, contamination of the crucible materials, melting incongruency, remarkable anisotropic growth rate and intergrowth of Bi-2201 phase, are discussed in detail.
1996, 45 (9): 1570-1577.
doi: 10.7498/aps.45.1570
Abstract +
In Fe-doped Tl-1223 superconducting phase, Fe-dopants significantly destroy superconductivity . Hall coefficient, thermogravimetric measurements and M?ssbauer effect show that Fe-dopants not only directly destroy the integrity of Cu-O layers to low superconduction transition temperature, but also induce extra oxygen to enter lattice. These extra oxygen defects can strengtheningly bind carriers in Cu-O layers, Such binding effect gives rise to decreasing of the carrier density with Fe-doping level increasing. In addition. the extra oxygen results in a deviation of its neibouring Fe(Cu) from center of Cu-O network, and from a new Fe-O coordination. It is important for high-Tc superconducting mechanism to study the structural details and carrier-binding effect of extra oxygen defect on superconducticity.
1996, 45 (9): 1578-1585.
doi: 10.7498/aps.45.1578
Abstract +
The modulated structure of Bi2Sr2CaCu2Oy single crystals has been observed and studied in detail with an X-ray rotating-anode diffractometer, indicating that the satellites of Bragg reflections are stretched along the c* direction in reciprocial space. It is the result of the stretch that the widened peaks are incompatible with a B-centered orthorhombic bravais lattice , and the intensities of satellites become asymmetry. The superlattice based on the lattice mismatch is not orthorhombic but monoclinic and perhaps forms superlattice twin structure in Bi-2212 single crystals.
1996, 45 (9): 1586-1591.
doi: 10.7498/aps.45.1586
Abstract +
After the treatment of porous Si by "amine immersion and rapid thermal oxidation", the peak position of the photoluminescence spectra has a blue shift to 500nm. Only a little change in photoluminescence was observed after 160d storing in dry air. FTIR spectra indicate that the compositions of such treated sample are mainly silicon and oxygen. ESR signal shows that the blue/green light-emitting sample has rather low density of dangling bonds. These results demonstrete that the quantum confinement effect and surface states play a key role in blue/green light emitting. This method is simple and practicable, to make blue/green light-emitting samples and its success ratio can achieve 70%.
1996, 45 (9): 1592-1600.
doi: 10.7498/aps.45.1592
Abstract +
The photoluminescence of spontaneously ordered Ga0.5In0.5P alloy has been measured at room temperature and under hydrostatic pressure up to 7GPa. The direct-band gap of three ordered samples is lower than that of disordered sample by 115,92 and 43 meV at normal pressure, respectively. Their pressure coefficients are also reduced from 92meV/GPa of the disordered sample to 75,81 and 83meV/GPa for three ordered samples. Both the narrowing of the band gap and the reducing of its pressure coefficients can be well explained using a Γ-Ｌ interaction model. The obtained Γ-Ｌ interaction poteraction potential is 0.19,0.15 and 0.10 eV for three ordered samples, respectively. It confirms that the [111] order in the spontaneously ordered Ga0.5In0.5P alloy is the main reason for the band-gap narrowing. An obvious Γ-X anticrossing has been observed in sample C,but the Γ-X interaction potential(0.011eV)is one order of magnitude less than the Γ-L interaction. It indicates that a weak [001] order coexists with the main [111] order in sample C.
