Vol. 32, No. 3 (1983)
1983-02-05
CONTENT
1983, 32 (3): 285-293.
doi: 10.7498/aps.32.285
Abstract +
In this article, the wave solutions of multivariate master equation for linear reaction system: A→X have been discussed. Except the density waves which is obtainable from the usual reaction diffusion equation and multiwave solutions, it is not possible to obtain any fluctuation wave branch like that given in ref. [2]. We note that, due to the large difference between the spatial scales of chemical reaction and diffusion, it is doubtful to use the multivariate master equation in analysing the critical behaviour of non-linear system.
1983, 32 (3): 294-300.
doi: 10.7498/aps.32.294
Abstract +
The formation of characteristic layered inclusions in the single crystal of potassium acid phthalate (KAP) is discussed in view of the effect of its microscopic structure. That three types of micro structural channels trap the impurities or other different phase precipitates in solution, via a special pair of the conical planes with the highest growth rate and the fluctuation of the growth conditions in liquor, is the main mechanism of inclusion formation. The above argument is in fair agreement with the experimental results for real crystals.
1983, 32 (3): 301-308.
doi: 10.7498/aps.32.301
Abstract +
The characteristic of optical bistability is analysed theoretically for the photoelectric modulator with a feedback circuit. The effect of the "critical slowing down" for a step input as it operates in the bistable mode is discussed.
1983, 32 (3): 309-314.
doi: 10.7498/aps.32.309
Abstract +
The F-P passive optical oscillator with two feedback circuits is described. This oscillator transforms an input with continous intensity of light into multi-vibrating optical pulses or optical sinusiodal signal output. The principle of oscillation is analysed. The experimental results in agreement with the analysis are presented.
1983, 32 (3): 315-324.
doi: 10.7498/aps.32.315
Abstract +
We present here a model of the reduction of dislocations in LPB layers by the formation of oriented interfacial dislocations parallel to the surface of the substrate due to the glide motion of substrate threading dislocations which is drived by the thermal stress produced by a temperature difference. In the temprature gradient LPE under a steady natural convection flow, there is a temperature difference across the thickness of the substrte. The temperature difference can cause a thermal shear stress in the fixed substrate. Thick GaAs and Ga1-xAlxAs (x oriented dark line defects. The observation of subface etch pits shows that the epitaxial layers have lower dislocation densities than that of the substrates or are even dislocation-free. The observations of interfacial etch grooves and cathodoluminescence show that substrate threading dislocations bent so that segments run along the interface and a interfacial dislocation network is formed. The transmission electron microscopy observation shows that the majority of these interfacial dislocations are 60° type dislocations and the minority are Lomer dislocations. It implies that it is possible to eliminate all substrate threading dislocations with the introduction of interfacial dislocations by thermal shear stress.
1983, 32 (3): 325-337.
doi: 10.7498/aps.32.325
Abstract +
Starting from the Vlasov-Maxwell equations by using the method of Self-Consistent field theory, we set up first the coupling relation between distribution function and density of low-frequency oscillating particles and high-frequency EF, low-frequency MF in fourier representation. Then, in the time-space representation, a set of equations for the nonlinear interaction including the effects of magnetic field generation, pondermotive force and Landau damping were derived through the expansion of the low-frequency linear dielectric function under various approximations. Finally, we also gave the Lagrangian density and conserved quantities and discussed briefly whether the magnetic field can promote the formation of soliton in three dimensions.
1983, 32 (3): 338-345.
doi: 10.7498/aps.32.338
Abstract +
A new mechanism of current driven by a wave is discussed. There is a series of resonant regions in the velocity space of a magnetized plasma interacting with a single wave. When the amplitude of the wave is higher than a threshold, some of the resonant regions will overlap each other and the stochastic effect will appear. If the overlapping region is asymmetric in the longtudinal velocity distribution of the electrons, the plasma current may be driven by the wave as a result of the stochastic effect.
1983, 32 (3): 346-353.
doi: 10.7498/aps.32.346
Abstract +
The exciton transition 4T1→6A1 of Mn2+ ions in quasi one-dimensional antiferro-magnet CsMnCl3·2H2O is very weak in intensity with a shorter lifetime due to the vibration-queching. Replacing H2O by D2O), three important effects have been observed: the exciton line is shifted to the red by 18cm-1, the intensity of the exciton is increased by almost one order, the lifetime is lengthened from 0.58 ms to 9.2 ms. These facts show that the vibration-quenching has been weakened. The experimental results are analysed by means of the theory of multi-phonon radiative and non-radiative transitions. It has been shown that the isotope substitution changes the spectrum of lattice vibration, and brings forth a great influence on the non-radiative transition. The electronphonon coupling intensity does not show any obvious change, and the Huang-Rhys factor remains constant. The phonon modes involved in the multi-phonon radiative transition are different from those involved in the multi-phonon nonradiative process, their average energies are quite different from each other.
1983, 32 (3): 354-359.
doi: 10.7498/aps.32.354
Abstract +
The rapidly quenched La80Al20 alloy is amorphous. At atmospheric pressure, its crystallization temperature and glass temperature are ～280℃ and ～242℃ respec-tivily, according to DTA measurements. The superconducting transition temperature Tc increases from 3.87 to 4.18K, in the hydrostatic pressure range of 1-4770 bars, while its residual resistance decreases significantly. After high pressure-high temperature treatment (25kbar, ～160℃, 40 min), amorphous→crystalline transition of La80Al20 alloy occurs, as disclosed by X-ray diffraction method. The product consists of α-La phase and a new metastable phase, and its Tc increases from 3.9 to 5.7 K. Some preliminary discussion on the experimental results are also presented.
1983, 32 (3): 360-365.
doi: 10.7498/aps.32.360
Abstract +
This article is a brief summary of our study on poisoning and regenerating at the surface of LaNi5 by impurities, which are H2S, SO2 and CS2 contained in the hydrogen used. The AES, XPS analysises show that the feature of the poisoning for three sulfides are different: LaNi5 poisoned by H2S produces the surface compounds, such as La2S3 and NiS. The chemisorption and physisorption occured due to SO2 and CS2 poisoning respectively.In addition, surface catalystic property of active nickel on LaNi5 can be shown by evalution of the changes in the intensity of nickel peak in the Ni(2p3/2) spectrum. Pure hydrogen cycle method is effective for regeneration of LaNi5 poisoned by SO2 and CS2, but this is not true for H2S-poisoned samples. These results are very useful in explaining the mechanisms of rare earth intermetallic hydrides surface poisoning and regenerating.
1983, 32 (3): 366-375.
doi: 10.7498/aps.32.366
Abstract +
By using the irreducible tensor operator method, two corollaries have been derived from generalized Wigner-Eckart theorem and the results associated with the corollaries are obtained. For the. d2 ions in a trigonally distorted cubic crystal field, the effective method dealing with overall problems of D, g‖, g⊥ and absorption spectrum has been suggested on the basis of unified model, in which all possible interaction of Vc and (Vtr + Hs) have been considered.In application to vanadium corundum, successful results in agreement with the experiments are obtained by overall fitting of the theoretical values to the observed values of D,g‖, g⊥ and absorption spectrum.The problems concerned in our model and methods have been discussed.
1983, 32 (3): 376-392.
doi: 10.7498/aps.32.376
Abstract +
In this article, the aberration theory of the combined electromagnetic focussing cathode lenses is described, and the two previous representative papers concerning the aberration theory of cathode lenses, the first contributed by Ximen Jiye (1957) and next by B. B. Bonschtedt (1964), are emphatically analyzed and commented. It is shown that the formulae of aberration coefficients for the cathode lenses given by them, although different in form, can be transformed from one to another; and it is enough to prove that the criticism of B. E. Bonschtedt addressed to Ximen Jiye, is improper.It is worth noicing that the aberrations of cathode lenses must be considered atthe image plane with regard to ε(x1)-a certain initial energy of electron in axialdirection, then the formulae of all the transverse aberrations including the first order and third order aberrations for the combined electromagnetic focussing cathode lenses can be derived. It is expected that these formulae will be closer to practice than those derived formerly.
BRIEF REPORT
1983, 32 (3): 393-399.
doi: 10.7498/aps.32.393
Abstract +
We have calculated the project range for ions on amorphous targets made of ternary or quarternary alloys. Our calculations are based upon Vagard's law, which establishes that the project range in multi-component system can be obtained by linear combination of those of its composing binary alloy compounds. The calculated project ranges of systems, H+→GaAlAs, InAs and InGaAs, Be+→ GalnSb and InAsSb, and B+ →Cd0.2Hg0.8Te, agree well with the experimental or calculated results published in literatures. The dependences of project range on implanting energy and composition in the processes H+→ GaInAsP and GaAlAsSb, and ions→ PbSnTe are also calculated.
1983, 32 (3): 400-405.
doi: 10.7498/aps.32.400
Abstract +
The crystal of dimethyl sulphoxide complex of yttrium [Y(NO33·3DMSO] belongs to the monoclinic system, α= 13.604(4)?, b= 12.669(4)?, c= 11.554(2)?, β= 100.14(4)° and Z=4. The space group is P21/n. The diffraction data were collected using PW-1100 four-circle diffractometer. The number of independent diffraction data amounts to 3615. The structure was solved by heavy-atom method. Structure parameters were refined by full matrix and block diagonal least square method to a final R = 0.080. The result of structure analysis establishes that the polyhedral coordination of " three-headger triprism" is formed by nine oxygen atoms surrounding the Y cation. The distances between the yttrium and the coordinating oxygens are Y-ODMSO = 2.285?, Y-ONO3-= 2.460?.
1983, 32 (3): 406-410.
doi: 10.7498/aps.32.406
Abstract +
Sodium deposition in β-, β"-Al2O3 and Nasicon (Na3Zr2Si2PO12) was studied by using EPMA. Based on the mechanism of ion transportation and electrolytic deposition with a diminished carrier concentration, a kinetic equation for sodium deposition has been derived, which can fit well the time dependence of the sodium counts during electron bombardment. Since an abundant source of mobile Na+ ions exists in the large single crystal, the rise of the curve of beta-Al2O3 extends over a long period of time. However, the crystallites in the Nasicon polycrystal are small (+ ion therefore may be provided insufficiently at the electron bombarded point for a prolonged deposition due to the hindrance of the grain boundaries in the ion transport process. The deposition attains its saturation limit rapidly.
1983, 32 (3): 411-416.
doi: 10.7498/aps.32.411
Abstract +
By employing the method of ligand field theory, we calculated the additional potential energies of d electron states of V3X(X = Si, Ga, Ge, Sb, Sn) superconducting compounds, these energies are induced by the D2d) crystal field. We obtained the analytic relation between the. lattice constant and the relative displacement of d sublevels △E⊥, which is the characteristic quantity for the model of d band relative displacement. The numerical values of △E⊥ and the magnetic susceptibilities calculated by using them are also presented.
1983, 32 (3): 417-422.
doi: 10.7498/aps.32.417
Abstract +
A method for measuring the positron 3γ annihilation, with Ge(Li) detector is introduced, in which the relative yields of 3γ annihilation is measured by the counts of the 511 keV peak only. We call it the "peak method", and compare it with the "peak-valley method."
