Vol. 32, No. 8 (1983)
In this paper, we study the space speckle motion induced by deformation of the object surface. According to the Fresnel-Kirchhoff Integration, three fundamental equations of the speckle motion induced by deformation of the surface are obtained. From these fundamental equations and those obtained in ref. , a general formula of the speckle motion is derived. The experimental results are in agreement with this formula. The physical explanation of these fundamental equations is presented.
1983, 32 (8): 982-989. doi: 10.7498/aps.32.982
Green's function of the wave equation for a perfect crystal is obtained by means of Fourier integration. Using Green's formulae, the expression of X-ray transmission wave field, D0 Dh, have been derived. With incident spherical and plane wave, Dh,D0 value are found and compared with previous results of other authors. Relationship between thickness of the sample and D0, Dh is discussed.
A MATRIX THEORY FOR OPTICAL PASSIVE RESONATORS (IN CYLINDRICAL COORDINATES) (I)——MATRIX EQUATION OF THE SELF-CONSISTENT FIELD
1983, 32 (8): 990-1001. doi: 10.7498/aps.32.990
In this paper, we discuss the matrix equation of the self-consistent field in an optical passive resonator, which was proposed in the previous paper on the basis of a matrix theory for the light propagation. A new understanding of the self-consistent field, the concept of the transform of element modes and the method of analysis of the element mode structure of the self-consistent field are presented here. It has been proved in general that the above mentioned matrix equation can be truncated into finite order so as to be solved approximately. The rigorous formula used to determine the superior limits of the errors of the eigenvalues followed from using the finite order matrix equation is given in general, and some other formulae, which are more convenient than it, are also given.It is shown that the matrix theory for optical passive resonators is very suitable for calculating modes containing the high-order modes whose diffraction losses are very close to unity. The author believe that this theory should also be suitable to analysis and design of complicated resonators.On account of the coordinates used, the theory presented here is only suited to systems with ideal axial symmetry.
A MATRIX THEORY FOR OPTICAL PASSIVE RESONATORS (IN CYLINDRICAL COORDINATES) (II)——CALCULATION FOR AXIAL SYMMETRIC STABLE RESONATORS
1983, 32 (8): 1002-1016. doi: 10.7498/aps.32.1002
Attempts are made to explore the way of solving the problem of calculating modes in optical passive resonators on the basis of the matrix equation in the previous papers, and to determine the superior limits of calculation errors resulting from truncating the matrix equation. For convenience of comparison between the results of ours and those obtained previously by other methods in literatures, we have calculated the characteristics of the modes in various stable resonators with two symmetric reflectors for Fresnel numbers N ≤ 1, and have determined the superior limits of the calculation errors using both the trial method of mathematics (the matrix has been truncated into various order to solve the matrix equation) and the rigorous formulae derived in the previous paper in general. It is shown that the superior limits followed from these formulae are resonable for all modes, including high order modes, but they are far larger than real errors. So that a new formula, which is more suitable for determining the superior limits of errors in our calculation than the previous one, has been adopted.Some new characteristics of the modes are obtained.It is obvious that, by means of the matrix equation, all modes in a resonator, whose losses are not very close to unity, with various radial mode numbers p and an arbitrary given angular mode number l can be caculated at a time, It has been found that a satisfactory accuracy can be achieved for the modes in resonators 0 ≤g≤0.95 in our calculation,provided the matrix equation is truncated into (N + 1) order, where N≥ 8N(1+g)1/2-l/2.
THE MODE OF SOUND IN GASEOUS SUPERFLUID FILM OF SPIN POLARIZED HYDROGEN ATOMS (H↓) ABSORBED ON HELIUM FILM
1983, 32 (8): 1017-1026. doi: 10.7498/aps.32.1017
The mode of sound in gaseous superfluid film of spin polarized hydrogen atoms (H↓) absorbed on helium film is discussed. Principally, it ia the fourth sound in two dimensions resulting from compressibility of the gaseous film and different from the usual third sound resulting from the variances of thickness of helium film.
In this paper, a theory of "clumps" in drift-wave turbulence is developed, based on the stochastic treatment of trajectories developed by Misguich and Balescu. It is shown that there exists a clump effect in a magnetized turbulent plasma as well as in an un-magnetized one. The existence of this effect makes the actual diffusion across the magnetic field much smaller than the diffusion predicted by Dupree's theory. Ah explicit expression for the clump life-time is derived this life-time is proportional to the diffusion (across magnetic field) characteristic time and depends logarithmically on the initial relative position of particles.
1983, 32 (8): 1035-1042. doi: 10.7498/aps.32.1035
We have discussed the spontaneous magnetic field in a spherically symmetric laser plasma. The expression for the spontaneous magnetic field due to TE wave is derived. This solution is contrasted with results of S-polarized wave in a planar plasma. By means of our theoretical result, the performance of the spontaneous magnetic field observed in recent experiments can be explained.
1983, 32 (8): 1043-1052. doi: 10.7498/aps.32.1043
The influences of various factors of dielectric target in certain pick-up tubes, storage devices and electro-optic display devices on the resolution are studied in this paper. By considering the general case of anisotropic dielectric target, the optical transfer function (OTF) from surface charge raster pattern to potential or optical pattern of dielectric target is deduced. The resolution limit of the dielectric target is analyzed quantitatively. The leakage of electricity on surface and the influence of the other medium film layer introduced on target surface on the resolution are discussed in detail. For example, the MTF curves of silicon target in pick-up tubes, polystyrene target in video tape and anisotropic medium target of DKDP crystal in large screen projection TV are calculated by TQ-16 type computer, then the resolutions of these targets are found accordingly. The results obtained well coincide with the experimental curves and data in literatures. Finally, the calculation results are further confirmed by experiments on DKDP crvstal.
1983, 32 (8): 1053-1060. doi: 10.7498/aps.32.1053
A single-crystal X-ray diffraction analysis has been performed on fergusonite BiVO4 synthesized by pulling method. At room temperature the crystal belongs to monoclinic system, with space group B2/b, z = 4, and cell parameters a = 7.247?, b=5.096?, c = 11.702? and r =134.18o. The structure has been analysed by two and three-dimensional Patterson procedure, and calculated through three-dimensional electron density. A full-matrix, least square refinement gave R=0.067, Rw =0.058 for 335 independent reflections. An absorption and secondary extinction correction gave final R = 0.058. The Bi and V atoms occupy a respective set of 4e special positions and the O atoms two sets of general positions. The oxygen atoms take part in four-fold coordinations around vanadium in the sense that they form regular VO4 tetrahedra. The structure also shows eight-fold oxygen coordinations around bismuth and form distorted Bi-O dodecahedron. The space groups for temperatures above and below Tc are found to be I41/a and 12/b (or B2/b) respectivelv. The phase transition from tetragonal to monoclinic does skip over a possible intermediate orthorhombic modification. The phase transition is apparently driven by a lone-pair distortion of the Bi-O polyhedron. Bi3+ and V5+ displace alternatively up and down along the c axis, resulting in a layer-like Character for monoclinic BiVO4 The character has been proved by optical observations. The BiVO4 crystal cleaves easily to give smooth (cleavage) faces parallel to plane perpendicular to the c axis.Three kinds of samples, i.e crystals with cell-like structure and disc shape, crystal ribbon with natural cleavage and powder crystal grain, were used for optical observation, and the relationship between the transmittance of BiVO4 and optical wave-length was studied.
1983, 32 (8): 1061-1067. doi: 10.7498/aps.32.1061
Phase transitions of Li3VO4, Li4SiO4 and isothermal section of the pseudo-ternary systems Li3VO4-Li4SiO4-Li4GeO4 have been investigated by means of DTA and X-ray diffra-ction techniques. It has been found that the high temperature phase of Li3VO4 can be stabilized to room temperature by addition of Li4SiO4 (or Li4GeO4) in Li3VO4-Li4SiO4 (or Li3VO4-Li4GeO4) binary systems. New Li+-conductors with high Li+-conductivity has been obtained. Experimental results show that stabilization of high temperature phase exhibiting high ionic conductivity could be one of the way for exploring new Li+-conducting materials.
THE VARIATIONS OF QUASIPARTICLE NUMBER OF SUPERCONDUCTING LEAD FILM IN NONEQUILIBRIUM PHASE TRANSITION
1983, 32 (8): 1068-1072. doi: 10.7498/aps.32.1068
We measured the variations of quasiparticle tunneling current It of the detector junction of a Pb-I-Pb-I-Pb junction with the injection current Ii in the range Vtt and Ii is approximately parabolical, after the appearance It increases much faster. The difference △It = It-It0, where It0 is the tunneling current in equilibrium state, decreases with the decrease of temperature.
1983, 32 (8): 1073-1078. doi: 10.7498/aps.32.1073
The departure of electronic distribution from local electrical neutrality and the additional energy due to such a departure in compositionally modulated structures are calculated using a simplified Thomas-Fermi equation. With this energy, we have derived the variation of the biaxial modulus with the modulation period. The result agrees at least qualitatively with experimental findings of supermodulus effect in such structures.
1983, 32 (8): 1079-1081. doi: 10.7498/aps.32.1079
In this paper, we report the I-V characteristics of rolling-quenched Al-Si-Ge strips. The results show the occurrence of voltage steps and hysteresis behavior in the superconducting transition region.
A NOTE ON THE NEGATIVE TEMPERATURE COEFFICIENT OF RESISTIVITY OF A Fe-25Mn-5Al-0.2C ALLOY IN LOW TEMPERATURE
1983, 32 (8): 1082-1085. doi: 10.7498/aps.32.1082
An anomalous behaviour of the negative temperature coefficient of resistivity of a crystalline bulk Fe-25Mn-5Al-0.2C alloy was observed at low temperatures. Below 50 K the resistivity is roughly proportional to InT. It seems that the anomaly is due to some land of magnetical mechanism.
NEW FORMULAE FOR CALCULATING MELTJNG TEMPERA-TURE, GRüNEISEN PARAMETER AND ISOTHERMAL PRESSURE OF METALS UNDER HIGH PRESSURE
1983, 32 (8): 1086-1092. doi: 10.7498/aps.32.1086
In this paper, a new melting equation is derived. Based on this equation, a formula for calculating Grüneisen Parameter and an isothermal equation of state are obtained through the Lindeman equation. We show that the new equations are reasonable by comparing them with known theoretical and experimental results.
THE CRYSTAL STRUCTURE OF D,L-PHENYLALANINE ETHYL ESTER CHLOROPLATINITE [C_6H_5CH_2·CH(NH_3)~+CO_2C_2H_5]_2·[PtCl_4]
1983, 32 (8): 1093-1097. doi: 10.7498/aps.32.1093
The space group of the crystal of the title compound is P2/a, with unit cell constants a=12.006, b = 8.398, c= 14.261? ,β= 93.98°. the cell contains two formula units of [phCH2CH(NH3)+CO2C2H5]2? [PtCl4]. The structre was determined from 1759 observed reflections and refined by the block-diagonal least-squares method to R = 0.038. The platinum atoms occupy one set of symmetrical center special positions. The [PtCl4]2- ion is coplanar with Pt-Cl bond, the bond lengths are 2.304(3) and 2.294(3)?, The discreate phenylalanine ethyl ester does not coordinate to the platinum atoms. The [PtCl4]2- ion and [phCH2CH(NH3)+CO2C2H5] ions are connected by ionic fores and hydrogen bonds between the nitrogen and chlorine atoms. Therefore this compound is an adduct of phenylalanine ethylester with anion of chloropladnite.
1983, 32 (8): 1098-1103. doi: 10.7498/aps.32.1098
The transmit tance curve of the LiNb3O8 crystal is determined. It is clear that the existence of oxygen vacancy is the basic reason of blackening of the crystal and the black colour can be bleached by annealing. It is shown that the cause of the hydrogen bond formation is a chemical reaction of the atmospheric water vapor with the melt. Vacumm annealing is a method to eliminate the hydrogen bond. Crystal growth in pure oxygen atmosphere is suggested. Three principle indices of the LiNb3O8 crystal and the directions of corresponding principle axes with respect to crystallographic axes are determined. And the refractive index of the LiNb3O8 crystal is compared with that of the LiNbO3 crystal. The relationship of the principle indices with the crystal structure is discussed.
1983, 32 (8): 1104-1108. doi: 10.7498/aps.32.1104
In order to understand the mechanism of the ionic conductivity enhancement during pre-crystallization process, we have performed 7Li NMR investigations on amorphous ionic conductor Li2B2O4. The temperature dependence of 7Li NMR spectra is studied. It is found that 7Li NMR spectra in crystalline, amorphous samples and amorphous sample with small amounts of crystallites are very different from each other. An additional peak is observed to overlap 7Li NMR absorption line on amorphous sample with small amounts of crystallites. This phenomenon is similar to that in LiCl (or LiI) containing dispersed secondphase particles. 7Li NMR investigations on amorphous ionic conductor B2O3-0.7Li2O-0.7LiCl is also made, the results are similar to that mentioned above. It is concluded that they are all caused by the interfacial effect between amorphous matrix and the crystallites.