Vol. 30, No. 7 (1981)
1981-04-05
CONTENT
1981, 30 (7): 857-865.
doi: 10.7498/aps.30.857
Abstract +
Applying BBGKY equation obtained from Liouville's equation to a system with many components, the irreversible chemical reaction-diffusion equation can be deduced.
1981, 30 (7): 866-877.
doi: 10.7498/aps.30.866
Abstract +
Recently, Wu and his coworkers formulated an infinite order perturbation theory for solving the Green's function of a disordered system, using a diagrammatic technique. In this paper, the method of matrix partition is used to obtain the same series of recursion relations, thus providing an algebraic proof for the theory.
1981, 30 (7): 878-886.
doi: 10.7498/aps.30.878
Abstract +
This paper is the first part of a theory of the coherent propagation of light in semiconductors. When the interaction between electrons is neglected we obtain the Bloch equation describing the matrix elements of interband transitions induced by coherent light in semiconductors. The interband transitions in the system are analogous in form to those of an inhomogeneously broadened two-level system, but a particular type of multiphoton process will occur under the action of intense light.
1981, 30 (7): 887-894.
doi: 10.7498/aps.30.887
Abstract +
The degrees of LEO (Long Range Order) and magnetic moments of the Fe atoms in a Fe-Si-Al alloy have been determined by neutron diffraction. The results indicate that after heat-treatments with different cooling rates, the alloy gains different degrees of LRO, which may be regarded as the main cause giving rise to significant, differences in the magnetic permeability.
1981, 30 (7): 895-907.
doi: 10.7498/aps.30.895
Abstract +
The K-series X-ray intensities of eight pure elements (from Al to Ge) and the L-series X-ray intensities of four pure elements (from Ni to Ge) excited by 15-30 keV electrons have been measured. Using the modified and simplified "full diffusion" electron diffusion model the ratios of the characteristic X-ray intensities) of these pure elements have been calculated. The back scattering effect is included in this model itself and the absorption correction factors are obtained from the stepped intensity-depth distribution derived from this model. Moreover the continuum fluorescence effect is also considered. The calculated values are in agreement with the experimental data, therefore the reliability of the model is verified.
1981, 30 (7): 908-915.
doi: 10.7498/aps.30.908
Abstract +
68 space groups of the tetragonal system have been analysed for the case of crystals containing one heavy atom in the asymmetric unit. Possible heavy atom positions which lead to multiple solution of the light atoms are tabulated together with the corresponding pseudo-symmetry, the multiple solutions of light atoms and the distribution rule of the components of structure factors among different parity groups.
1981, 30 (7): 916-920.
doi: 10.7498/aps.30.916
Abstract +
Information drawn from the heavy atom plays an important role in the determination of crystal structures containing heavy atoms. To what extent would the determination proceed successfully depends on how the heavy atom information should be used. In this paper a new procedure is proposed to make full use of the heavy atom information and make the combination between heavy atom method and direct method more efficient.
1981, 30 (7): 921-927.
doi: 10.7498/aps.30.921
Abstract +
The heavy atom phases are extremely important in solving crystal structures containing heavy atoms. Successive Fourier approximation and Karle recycling procedures starting with the heavy atom phases are two major methods of solving structures containing heavy atoms. However, difficulties may some times happen when the contribution of heavy atoms is too small to dominate sufficient number of phases or if the distribution of heavy atoms possesses a higher symmetry than that of the whole structure. It is worthy to investigate in these cases whether or not the heavy atom information can still be used to simplify the process of structure determination greatly. In this paper a method is proposed that the heavy atom phases may be used to restrict the permutation of the starting phases leading to a great reduction in number of the starting phase seta. This method incorporating with that proposed by the authors can improve greatly the efficiency of direct methods in solving structures containing heavy atoms.
1981, 30 (7): 928-935.
doi: 10.7498/aps.30.928
Abstract +
It is found in Eef. [1] that a band of scattered light is produced when a laser beam passes through an α-LiIO3 single crystal under the action of a DC field along the c-axis. The electric vector of the scattered light has special direction which differs from that of the incident beam. In this paper, we have further investigated the characters of this scattering of light. The fine structure of the band has been studied. No frequency shift between the scattered and incident beam larger than 15 MHz has been. observed. The distribution of intensity of the band is asymmetric with respect to the transmitted light spot, one side is stronger than another. We have found that the distributions of intensity of the scattering band are inverse for the two types of absolute configuration of α-LiIO3 single crystals, that is the stronger side of the band for the D type crystal corresponds to the weaker side for the L type crystal. We have also studied the relationship between locations of bands and that of the transmitted light spots, and found it is dependent on the orientations, of the incident and exit surfaces of specimens with respect to the c-axis of the crystal.
1981, 30 (7): 936-944.
doi: 10.7498/aps.30.936
Abstract +
Using microwave network theory, this paper presents an analysis of open resonators in the form of waveguide with slowly-varying cross-section. A general formula for determining the trasmission Q value of the open resonator with any longitudinal profile is given. The value of Q resulting from the lossy wall is estimated. The correction of the resonant frequencies is discussed. As examples we derived the formulas to calculate the Q value for dual-cone open resonators and that for cylindrical open resonators.
RESONANT ABSORPTION AND SECOND-HARMONIC GENERATION AT A RIPPLED CRITICAL SURFACE IN THE LASER PLASMA
1981, 30 (7): 945-952.
doi: 10.7498/aps.30.945
Abstract +
When laser beam is incident on an inhomogeneous isotropic plasma, the variations in density profile perpendicular to main density gradient may develop, producing a rippling of critical surface. We have discussed resonant absorption and second-harmonic generation at the rippled critical surface in the case of normal incidence. Analytic expressions for absorption and transformation coefficients are derived. It is possible to explain reasonably the deviation of linear theory from experimental results with this mechanism.
1981, 30 (7): 953-961.
doi: 10.7498/aps.30.953
Abstract +
As the total circumstance radiation which falls on the target being taken as the equivalent radiation of a blackbody at temperature T0, the effect of environment radiation change on the sensibility equation of thermal imaging system is studied, and consequently the ratio emissivity ε of the target can be determined theoretically through the change of environment radiation. This paper gives the method and the measurements of temperature of the environment equivalent blackbody T0 Also a new method is given about the thermometer measurement of the ratio emissivity of the target. When the environment radiation is not neglected, the problems are methodically and theoretically discussed about how to use a ratio radiometer to measure the real temperature T of the target and how to use the radiometer to measure the spectral reflectivity of visible light from ground target.
BRIEF REPORT
1981, 30 (7): 962-967.
doi: 10.7498/aps.30.962
Abstract +
We investigated the near resonant scattering and collision induced fluorescence of sodium atoms with doublet excited states in a weak laser field. By changing the frequency of the incident light and measuring the integral intensities of the components of the scattered light, the near resonant excitation cross-section of each sublevel was obtained as functions of the frequency detuning. Their variations are qualitatively explained by the interaction potential between the sodium atom and various collisional perturbing species. We have measured the variation of the induced D1 and D2 fluorescence with laser power, density of sodium atoms and pressure of buffer gas. It is shown that the relation is linear. The experimental results are in agreement with the theory.
1981, 30 (7): 968-971.
doi: 10.7498/aps.30.968
Abstract +
The problem on gauge transformation of the tensor potentials (A and B) associated with the dislocation field is treated. It is shown that the expressions of this transformation may take the form B′=B+▽F, A′=A-ρ?/(?t)▽G,x′=x-ρ?/(?t)F, where xi=eiklAkl. F and G are some arbitrary vector functions of position and time, but they must satisfy the relations F=▽×G,▽2F-1/Gt2-(?2/?t2)F=0. Furthermore, it is proved that the gauge conditions presented in [1] are compatible with the inhomogeneous wave equations for A and B
1981, 30 (7): 972-975.
doi: 10.7498/aps.30.972
Abstract +
The TiAl-VAL-MAl3 sections of the Al-Ti-V-M (M = Ni, Fe) systems at room temperature have been determined by X-ray diffraction method. (1) The TiAl3-VAl3-NiAl3 pseudoternary system is composed of the e(NiAl3) phase region, d phase region (the d phase is a continuous series of solid solutions formed from the compound TiAl3 with the compound VA13), and ε+δ two-phase region. (2) The TiAl3-VAl3-FeAl3 pseudoternary system is composed of the θ(FeAl3) phase region, δ phase region (the phase is the same as in the TiAl3-VAl3-NiAl3 system), and θ+δ two-phase region. No new phase has been found other then those already encountered in the four corresponding binary systems and the three corresponding ternary systems.
1981, 30 (7): 976-982.
doi: 10.7498/aps.30.976
Abstract +
The bromo-Qinghaosu (C17H27O5Br) crystal belongs to the monoclinic system, space group is P21, with a = 10.341?, 6 = 9.160?, c = 9.353?, β = 90°, Z = 2. The intensity data were collected on the Philips PW-1100 diffraetometer. Initial positional parameters (for double solution) were determined by a Patterson method. There are two heavy atoms bromine in the unit cell, it is centrosymmetric, that raises the problem of ambiguity. We have obtained a set of unique solution by means of chemical knowledge and direet method, respectively. Absolute configuration of molecule was determined by anomalous scattering method. Atoms coordinate parameters, ratio factor, isotropic and anisotropic temperature factors were refined by full-matrix least square method.
1981, 30 (7): 983-988.
doi: 10.7498/aps.30.983
Abstract +
Several possible parametric decay channels are studied in high field and dense Tokamay range. It is found that for the high power nearly perpendicular incident, electron cyclotron wave parametric processes may occur before it encounters the linear mode-conversion-layer. The pump wave decays into an ion Bernstein wave or a lower hybrid wave is most probable.
1981, 30 (7): 989-991.
doi: 10.7498/aps.30.989
Abstract +
A new theorem have been deduced from the completion of Hannsse's theorem. It states: "If reactants in the intermediate reaction are not more than two kinds and the numbers of molecule taking part in any one reaction are not more than two, then it is not possible that a steady state arrives at a limit cycle".
1981, 30 (7): 992-998.
doi: 10.7498/aps.30.992
Abstract +
Coherent Potential Approximation (CPA) for a n-component liquid alloy is derived by taking the limit of a generalized lattice-gas model, criminally formulated by Yonezawa and Watabe. We have taken the transfer integral tAB between atoms A and B as the geometrical mean of tAA and tBB. In the absence of short range order, our results are consistent with that obtained by Shiba using a coherent locator method.
1981, 30 (7): 999-1002.
doi: 10.7498/aps.30.999
Abstract +
It was the first time to investigate defects in YAG single crystal grown by Czochralski method by means of X-ray transmission topography. Several grown-in defects, such as growth striations, singular facets and dislocation bands perpendicular to the grown striation, were revealed. The configuration and formation of these defects were discussed in brief.
