Vol. 31, No. 9 (1982)
1982, 31 (9): 1141-1151. doi: 10.7498/aps.31.1141
In general, two dimensional dynamic NMR spectrum can be obtained by means of three-pulses experiment. But the informations from this experiment may sometimes be obscured if the scalar coupling in the nuclear system appears. In this work, a theoretical 2D dynamic NMR spectrum of weak coupled two spin system is calculated in Liouvelle space. The analytic solutions of density matrix in AX(I=1/2) system is given. It is shown that (1) after applying of gradient pulse, a z-component, a zero-quantum coherence and a double-quantum coherence will be left in the density matrix; (2) the effects of scalar coupling is different from those of exchange and relaxation and the former only contributes to the zero-quantum coherence and double-quantum coherence. Therefore, one can expect that the interference from the scalar coupling would be eliminated in some appropriate experiment.
This paper investigates the Bremsstrahlung in plasmas from the point of view of quantum statistics, thus eliminating the divergence which exists in the classical theory. We have treated the ion shielding effect rather strictly and obtained an expression clearly showing its influence. Finally, the corresponding absorption coefficient is given.
THE SLOWING DOWN OF FAST PARTICLES PASSING THROUGTH FUSION PLASMA AND THE ENERGY GAIN OF FUSION REACTION
1982, 31 (9): 1166-1175. doi: 10.7498/aps.31.1166
The extended Landau theory about slowing down of electron traversing through matter has been applied to the investigation of slowing down of fast charged particles passing through fusion plasma. It is shown that there are some obvious differences between the solution of Fokker-Planck equation and our results. These differences come from different descriptions for larger energy exchange events in collisions. As a con crete application of the present theory, the energy gain of the fusion reaction produced by mixed deuterium and tritium beam has been calculated and the significance of improving particle confinement time has been shown.
STUDY ON PRESSURE DEPENDENCE OF SUPERCONDUCTIVITY OF C-15 LAVES PHASE ALLOYS: (Hf, Zr, Ta)V2 AND (Hf, Zr, Nb)V2 SYSTEM
1982, 31 (9): 1176-1182. doi: 10.7498/aps.31.1176
The superconducting transition temperatures, Tc, and their pressure dependences ?Tc/?P of some C-15 Laves phase compounds, (Zr0.5Hf0.5-xTa)V2 (x≤0.2) and (Hf0.5Zr0.5-xNbx)V2(x≤0.2) system, have been studied. A description of the experimental apparatus and results is given. Unlike the cases of (Hf1-xTax)V2 and (Zr1-xTax)V2, introduction of Ta in (Zr0.5Hf0.5-xTax)V2 depresses Tc but causes a remarkable higher ?Tc/?P. So the superconducting transition temperature Tc of Zr0.5Hf0.45Ta0.05V2 is higher than that of (Zr0.5Hf0.5)V2 at high pressure. In view of the band theory method with angular momentum representation, a new relation for the pressure dependence of elect-ron-phonon coupling (i.e. ?lnη/?lnV) is derived. It emphasized the relative importance of high angular-momentum-partials variation of the conduction band electron wave function on ?lnη/?lnV. This formulation is helpful in understanding the above-mentioned experimental results and also gives a resonable explanation to the facts that Tc of some elements, e. g. Cs, Ba and La, are substantially enhanced by pressure.
1982, 31 (9): 1183-1190. doi: 10.7498/aps.31.1183
The superconducting transition temperatures Tc of systems V2Hf1-xNbx,V2Zr1-xNbx and V2Hf0.5Zr0.5-xNbx were studied. We found that Nb content influences SC Tc of V2Hf0.5Zr0.5-xNbx in a different way from that of V2Hf1-xNbx and V2Zr1-xNbx. X-ray photoelectron spectroscopy of V2Zr, V2Hf and V2Hf0.5Zr0.5 showed that the coexistence of Zr and Hf atoms in A sites of AB2 compounds results in a new type of electron density transfer enhancing the interaction of atoms. This fact supports the following explanation to Tc behavior: 4d-5d coordination of V2(HfZr) may favor the hybridization of 4d conduction band thus causing higher Tc.
1982, 31 (9): 1191-1197. doi: 10.7498/aps.31.1191
In this paper, we present the method and the experimental results of direct measuring of the true surface temperature for a body in the environment using the IR thermometer.The calculation of the equivalent blackbody temperature TB of the environmental radiation and the emissivity ε of the target on the basis of the temperature data of the IR thermometer is discussed.
1982, 31 (9): 1198-1205. doi: 10.7498/aps.31.1198
An n-Fe2O3 film was grown on a n-Si substrate which had undergone surface treatment to form a double layer semiconductor electrode. The influence of the interface state on the electrode properties was studied. From photoluminescence measurements, we found that an interface state with high density of states exists lying above the top of the Fe2O3 valence band at 1.61 eV. The Fermi level is pinned by this interface state.Using energy band profiles, we give an explanation for the photoluminescence, as well as a theoretical calculation and analysis for the capacity-voltage curves and photo-current-voltage curves. These theoretical calculated curves agree well with the experimental data. This double layer semiconductor electrode with an interface state with high density of states is a promising material for solar cells of good stability and high photoelectric conversion efficiency.
1982, 31 (9): 1206-1214. doi: 10.7498/aps.31.1206
Cebaite Ce2Ba3(CO3)5F2 is a new mineral discovered in China. Its electron diffraction spots can be divided into two groups according to the intensity. The stronger one results from the substructure which is similar to that of Huanghoite and can be described by a hexagonal subcell with parameters α0=5.06?, c0=9.63?, while the other group comes from the superstructure which belongs to monoclinic system. The parameters of the real unit cell are α=21.2? b=5.06? c=13.l? β=95°. The possible space groups are C2/m, Cm and C2. The basic vectors of the substructure and those of the superstructure in the real space are as follows :Some frings with spacing smaller than the original one and some broad black bands often appear in lattice images formed by h00 systematic reflexions. The cause of this is discussed. It is also discussed whether there is any superstructure with longer period in this mineral.
THE ENERGY-MOMENTUM PSEUDOTENSOR OF THE GRAVITATIONAL FIELD AND THE GRAVITATIONAL RADIATION EMITTED BY AN AXISYMMETRIC SYSTEM
1982, 31 (9): 1215-1222. doi: 10.7498/aps.31.1215
In this paper, we have calculated the total gravitational radiation emitted by an axisymmetric system per unit time. Direct calculation using Hu Ning's expression for the τ(n)αβ and Bondi's cylindrical wave solution has led to -(dE)/(dt)=1/2∫x0c02sinθdθ. This result is identical with Bondi's formula that has been obtained without using any expression for the ταβ and shows that the total power radiated is always positive. The result obtained from Zheng Yu-kun's expression for the ταβ, however, does not agree with Bondi's formula and indicates that total power radiated is not always positive.
1982, 31 (9): 1223-1234. doi: 10.7498/aps.31.1223
The objects with core (or with halo) are typical configuration in various astrophy-sical problems. The equilibrium and stability of the relativistic polytropes with a compact core have been discussed in this paper. Comparing with the normal polytropes, the relativistic loaded polytropes have many unique properties, some primary ones are:1. The distribution of density has a steep spike near the centre.2. The stable solution of polytropes with finite radius may exist only when the core satisfy some restricted conditions.3. When the polytropic index n≥3, the stable solution of equilibrium can also exist.
1982, 31 (9): 1235-1242. doi: 10.7498/aps.31.1235
Based on the previous work, we propose here a designing method of optical resonator with an elliptical refractive index profile of dielectric. Moreover, some influences of thermal effects on the transversal field distribution, the orientation of polarization, as well as output power of b-axis Nd: YAP(Nd+Cr:YAP)CW laser are analysed. With these factors taken into account, we have been able to achieve 163W and 152W laser output with nearly linear polarization beam from 5.8 ×111mm Nd: YAP rod and 6.4×100 mm Nd+Cr:YAP rod with an over-all efficiency of 2.26% and 2.11% respectively. The depolarization of the laser beam is about 1:2900.
1982, 31 (9): 1243-1249. doi: 10.7498/aps.31.1243
In this paper, we treat the dynamical form factor of one-dimensional kink-phonon gas as a whole by projection operator technique. Central peak and damped soft phonon-peak, which reflect the effect of kink-phonon interaction, are obtained. The central peak is considerably different from that calculated directly by using the renormalized average number of kinks.
1982, 31 (9): 1250-1255. doi: 10.7498/aps.31.1250
In this report, the γ-Fe2O3 fine particles with Co-doping was investigated by means of M?ssbauer effect of 57Fe.The experimental result indicates that the effective anisotropy constant of the γ-Fe2O3 fine particles doped with Co is about 30% greater than that of the superfine γ-Fe2O3 powder without Co. It provides a further explanation to the increasing of the coercivity of the ordinary needle γ-Fe2O3 powder with Co-doping.
1982, 31 (9): 1256-1262. doi: 10.7498/aps.31.1256
An investigation on the structures of the metal-metalloid glassy alloys Pd77Si16.5Ag6.59,Co42.9Ni27.3Fe7.8Si8B14 and Co50.7Ni19.5Fe7.8Si6B16 was carried out by means of X-ray diffraction method. The informations about the structure of these glassy metals such as the average atomic distance, the nearest coordination number and the radius of short range order were obtained from the radial distribution functions RDF(r). Besides, the Gaussian distribution formula were used to fit the first peak of RDF(r), and the best expression was found. The coordination number of metal-metal atoms was estimated approximately.
1982, 31 (9): 1263-1266. doi: 10.7498/aps.31.1263
In this paper, the essential features of the pseudo-symmetry in the superstructure of Huanghoite are discussed and the direct procedures of solving the superstructure are given in detail.
1982, 31 (9): 1267-1273. doi: 10.7498/aps.31.1267
In this paper, a one-dimensional 3-temperature calculation model of laser fusion is given, including the physical equations and the calculation method, with several typical examples presented to demonstrate the correctness of our model.
1982, 31 (9): 1274-1277. doi: 10.7498/aps.31.1274
The X and W phases exist in the LaxZnxBa1-xFe12-xO19 ferrites in the high temperature phase region. The Curie temperatures of the X and W phases were obtained at x=0 as 518℃ and 534℃ respectively. The substitution of Ba, Fe ions in the W phase by La, Zn ions is possible in the range of xf and anisotropy field HA descrease with increasing x for the W phase, whereas the saturation magnetization σs increase and the crystal anisotropy constant is approximately a constant value.
1982, 31 (9): 1278-1284. doi: 10.7498/aps.31.1278
In the present paper, we discuss the critical behavior of Thom-system using Catastrophe Theory. The universal critical asymptotic form of the family of free energy functions for Thom-system with one order parameter and two field parameters is obtained. The expressions of critical exponents, the scaling laws, the scaling hypotheses, all are derived from this universal asymptotic form.
1982, 31 (9): 1285-1288. doi: 10.7498/aps.31.1285
The fine structure of the dislocation pits, which are formed by HCl-Fe+++ etching solution, is observed experimentally. The correlation between structure features of the dislocation pits and the directions as well as slip planes of the dislocations is investigated. We discussed the kinetic processes in which the etch pits are formed. The results indicated that different rate of nueleation and velocity of lateral motion on the dissolution steps of 〈112〉and〈112〉 crystal orientations is the main reason which makes the dislocation pits have two kinds of dissolute edges with different features.