Vol. 41, No. 7 (1992)
In this article, the Gaussian curvature of the event horizon of a Kerr-NUT black hole is given. The effect of NUT parameter on the equatorial circumference and the polar circumference of the event horizon is analysed. The problem of embedding the surface in Euclidean 3-space is examined. It is shown that the event horizon of a Kerr-NUT black hole has the geometrical properties which other black holes do not porsess.
1992, 41 (7): 1063-1071. doi: 10.7498/aps.41.1063
In this work, a simple algebraic approach to the second quantization representation (SQR) for systems of many /identical particles is developed. In comparison with the traditional method, our method is simpler and elementary in mathematical operation, as well as is more transparent in exploring the mathematical structure and physical meaning of wave functions and mechanical quantities in SQR.
ZERO MOMENTUM BEHAVIOR OF ONE PARTICLE IRREDUC. IBLE DIAGRAMS FOR QUANTUM FIELD THEORY AT FINITE TEMPERATURE
1992, 41 (7): 1072-1080. doi: 10.7498/aps.41.1072
By using the closed time-path Green's function method, we investigate the zero momentum behavior of one particle irreducible diagrams for quantum field theory at finite temperature. It is shown that the zero momentum limits of the retarded form of these diagrams are no longer ambiguous provided that the "|p0| prescription", which implies the Kubo-Martin-Schwinger condition, is adopted.
1992, 41 (7): 1081-1086. doi: 10.7498/aps.41.1081
In this paper, we prove that forced Oregonator oscillator may be describled by cubic map, for there are three fixed points in four variables differential equations and the transfer function of chaos represents the character of cubic curve. We find the DSP symbolic description of 3-point cycle BK; C, 4-point cycle BK; LC, BK; C, BRK; C and draw a cycle line of BRK; C. We find two of one type in period-doubling bifurcations along a straight line. We studied five chaotic behaviours. Its dimensions are 2.02-2.37. In the middle region of chaos, its dimensions are slightly smaller, i.e., 2.02 to 2.09. Near the 4-point cycle line, its dimensions are 2.16 to 2.34.
ATOMIC AND MOLECULAR PHYSICS
1992, 41 (7): 1087-1091. doi: 10.7498/aps.41.1087
The soliton behavior of K2ZnCl4 crystal near commensurate-incommensurate phase transition point is investigated by dielectric measurement. It is found that the dielectric curve deviate from Curie-Weiss law and the dielectric peak value decrease with the increasing of the impurities. The influence of impurities on phase transition point Tch in heating run is larger than phase transition point Tcc in cooling run. This phenomenon is contrary to the case of Rb2ZnCl4 crystal. The linear and nonlinear response of a multisoliton lattice is well described by a Landau-type theory. Analysis shows that the thermal hysteresis is mainly determined by the action of impurities, but this does not imply that the Peierls lattice pinning potential may not play any role in the thermal hysteresis.
CLASSICAL AREA OF PHENOMENOLOGY
1992, 41 (7): 1092-1096. doi: 10.7498/aps.41.1092
The problem of stability of the equilibrium helical orbit in free-electron lasers with a combined ideal helical wiggler and uniform axial guide field is successfully solved by means of the Lyapunov's stability theory of motion. The unstable region is determined with perturbation of initial energy taken into account by Lyipunov's first method. An appropriate Lyapuov's function is constructed; accordingly, the low and high guide field stable regions are shown rigorously.
1992, 41 (7): 1097-1105. doi: 10.7498/aps.41.1097
In this paper, it is demonstrated theoretically that, under the strong dispersion condition, the optical waveguides made of the media with non-central symmetry where the second order nonlinear susceptibility (SONS) is not zero, e.g.the thin-film waveguides and crystalline fibers, can also support these solitons but the nonlinear-index coefficient (NIC) in the nonlinea schro-dinger equation should be substituted by the effective NIC defined here. The results obtained here can be easily extended to discuss the other nonlinear effects connected with the NIC in the media with noncentral symmetry because of the definition of the effective NIC.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
INVESTIGATION ON THE DEFECTS IN THE POST-DEFORM- ATION HYDROGEN-CHARGED POLYCRYSTALLINE PURE Co BY POSITRON ANNIHILATION
1992, 41 (7): 1106-1110. doi: 10.7498/aps.41.1106
Using positron lifetime and Doppler broadening lineshape parameter measurements, the recovery behaviors of defects in the deformed and post-deformation hydrogen-charged poly-crystalline pure Co have been studied. Experimental results indicate that the cathodic hydrogen-charging of deformed sample further introduce an additional amount of dislocations and vacancies as well as some vacancy clusters into it. However, it appears that mirrovoids and microcracks are not produced. The recovery temperature range of vacancies is 73-260℃; the annealing of dislocations and vacancy clusters occur in the range of 350-670℃. The migration activation energy of vacancy was measured to be 1.09±0.07eV.
1992, 41 (7): 1111-1118. doi: 10.7498/aps.41.1111
Undercooling behavior of Pd43.5Ni43.5P13 alloy was studied in a 20m drop tube. The solidified droplets were spheres with size ranged from 0.2 to 2.5 mm in diameter. The samples were examined by X-ray diffraction, scanning electron microscopy and X-ray energy dispersive spectrum. The results showed that when the alloy solidified in nitrogen at pressure of 1.8×104Pa, a near single phase of Pd-Ni-P fcc solid solution was obtained. This fact suggests that a partitionless solidification may occur during the solidification of the alloy in free fall. In addition, when the droplets solidified in nitrogen at pressure of 8.0×104Pa, an amorphous phase presented in the sample. This indicate that the sample had partially undercooled below the glass transition temperature Tg.
PHOTOACOUSTIC SPECTROSCOPY INVESTIGATION OF NH PHYSISORPTION ON CLEAN AND OXYGEN PRE-ADSORBED Cu SURFACE
1992, 41 (7): 1119-1124. doi: 10.7498/aps.41.1119
Ammonia physisorption on polycrystalline copper surface at 85 K has been studied by infrared photoacoustic spectroscopy. Much attention has been paid on the vibrational spectra of ammonia symmetric deformation mode and its band variation as a function of coverage. The different coverage dependent behaviors are exhibited for ammonia adsorption respectively on clean and on oxygen pre-adsorbed copper surface, and can be explained by assuming that ammonia follows different adsorption mechanisms. Studies of the minute discrepancy between them further illustrate the applicability of this technique in surface adsorption analysis.
TUNABLE-SAMPLING-DEPTH ELECTRON ENERGY LOSS SPECTROSCOPY AND AUGER ELECTRON SPECTROSC-OPY STUDIES OF Pb/Ni(001) INTERFACE
1992, 41 (7): 1125-1131. doi: 10.7498/aps.41.1125
We have studied the interface formation process of Pb/Ni (001) system by means of tunable-sampling-depth electron energy loss spectroscopy (TELS) and Auger electron spectroscopy (AES). During the deposition of Pb, the AES peak height ratio of Pb to Ni versus time of deposition consists of three segments with the two turning points corresponding to 1 mono-layer (ML) and 2 ML respectively, indicating the Franck-Van der Merwe, i.e. layer by layer growth mode. Also during the Pb deposition, the Pb 6s band ELS peak appears as the Pb coverage is beyond 1 ML, while the Pb bulk plasmon peak appears at about 2 ML of Pb coverage. During the whole process of deposition and annealing, the ELS peak position and width of the Pb bulk plasmon peak, the 6s band peak as well as the Ni 3p band peak maintain their own pure metal values, and there was no new bulk plasmon peak. In view of all these facts, we have reached the conclusion that there is no intermixing of Pb with Ni and the interface of this system is abrupt.
1992, 41 (7): 1132-1136. doi: 10.7498/aps.41.1132
The nanimeter-size crystalline Ti films have been manufactured by use of a sputtering deposition utilizing Electron Cyclotron Resonance (ECR) plasma at room temperature. The substrates are quartz glass, NaCl monocrystal and pure Al. The structure and the composition of the Ti films have been determined by using XRD, TEM, XPS. The results show that the granular Ti films consist of nanocrystal particles with the uniformi grain size, the average grain size d<10nm, and with a stable abnormal fcc structure. The influence of working parameters on the crystal structure, the grain size, deposition rate and adhension of the films have been studied systematically. The mechanism of depositing Ti films have been discussed.
1992, 41 (7): 1137-1142. doi: 10.7498/aps.41.1137
The critical cracking and damage mode of titanium nitride films on pure titanium substrate at ambient temperature were investigated by the Cantilever Bending test. Acoustic Emission technique was employed for identifying the onset of the films fracture which occured with the load increasing when the inner stress of the films σf reached its ultimate strength σc or the shear stress at the interface τf reached the adhesion strength τc. In terms of the above criterions, the initial cracking of the film on the top occured at the inner of films when the load was increased to a critical value, i.e. Lct = 800gf; Whilst the cracking of the film on the bottom started along the interface at the critical load Lcc= 1285 gf. In addition, the feature of the cracking and spalling of the film has been discussed.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1992, 41 (7): 1143-1146. doi: 10.7498/aps.41.1143
The excitation energy of soliton ε1 and its dependence upon electronlattice coupling: strength λ have been calculated in strongly coupled one dimensional electron-lattice systems. Our results show: The excitation energy of soliton ε1(λ) augments as λ increases. Whereas, ε1, will be always less than the energy needed to excite an electron or a hole in this system.
1992, 41 (7): 1147-1150. doi: 10.7498/aps.41.1147
The temperature dependences of the thermoelectric power of a single crystal Bi2Sr2CaCu2O8 were measured in both the a and b directions. We discovered the anisotropy of thermoelectric power in the a-b plane of the crystal. Suggeste that the differences between Sa and Sb are caused by the modulate structure in the b direction. A satisfactory explanation is given by taking into account the contributions of the relatively mobile electrons Sd, the relatively localized electrons Sh and the phonon drag effect Sg.
1992, 41 (7): 1151-1156. doi: 10.7498/aps.41.1151
By the substitution of Ca for Y, the holes are introduced into the insulating host material YBa2Cu3O6, and an insulator-to-metal transition, as well as superconductivity at 60K, is observed. The measurements of crystal structure, resistivity and ac susceptibility are performed, and the results indicate that the CuO planes with sufficient carrier concentration is the important condition for sustaining the high-Tc superconductivity.
1992, 41 (7): 1157-1161. doi: 10.7498/aps.41.1157
The superconductors with nominal composition of Bi2.0-xPbxSr1.9Ca2.2Cu3.3Oy were prepared by solid-state reaction method, XRD patterns were systematically studied for the samples. The results indicated that rich-Ca, Cu could accelerate the formation of (2223) phase, and broaden the sintering temperature range for a single phase. High-quality polycrystalline sample of 110K single phase was obtained. Annealing at lower temperature is beneficial to increase the volume ratio of 110K phase.
1992, 41 (7): 1162-1166. doi: 10.7498/aps.41.1162
We have performed a numerical simulation of the three-state vector Potts model on a three-dimensional random lattice. The averages of energy density, magnetization, specific heat and suscetibility of the system in the N× N× N (N = 8, 10, 12) lattices were calculated. These results show that this spin system exhibits an energetie thermal hyoteresis diagram and a sharp peak of specific, which could show that the system experierces phase transition with 1st ordes Z(3) symmetry breaking, this conclusion is supported by the law of the jump of magnetization. These results obtained on the random lattice were consistent with those obtained on the three-dimensional cubic lattices.
1992, 41 (7): 1167-1173. doi: 10.7498/aps.41.1167
The coercivity of cobalt-surface-modified γ-Fe2O3 particles is 8000 to 32000 A/m greater than that of the original γ-Fe2O3. The origins of uniaxial anisotropy and the mechanisms of the increase of coercivity of Co-γ-Fe2O3 and CoFe-γ-Fe2O3 particles are studied in this paper. The directional order (preferred orientation) of the cobalt ions appears on the surface of γ-Fe2O3, raises the surface uniaxial anisotropy and thus increases the coercivity of Co-γ-Fe2O3. The squareness ratios of various samples of CoFe-γ-Fe2O3 (Co/γ-Fe2O3 = 2 -16wt%) are obtaihed to be about 0.5. The coercivity of CoFe-γ-Fe2O3 is increased by the uniaxial anisotropy and multiaxial magnetocrystalline anisotropy strengthened after CoFe-coating. The origins of uniaxial anisotropy strengthened are suggested. The first is that directional order (preferred orientation) of cobalt ions on the surface of γ-Fe2O3 results in surface uniaxial anisotropy. The second is that the uniaxial anisotropy results from preferred alignment of preferred axis of cobalt ferrite microcrystal in surface layer of γ-Fe2O3.
1992, 41 (7): 1174-1181. doi: 10.7498/aps.41.1174
This paper presents a two spin-orbit (SO) coupling parameter model of g factor for Ni2+-6X- clusters. Using this model, the g factors of NaCl:Ni2+ and NaBr:Ni2+ are calculated. The molecular orbitial coefficients are determined by means of a semiempirical method in calculation of the g factors. The results show that the contribution from the SO coupling of ligand ions to the g shifts can not be neglected for ligand ion possessing large SO coupling constant such as Br- or I-. This suggests that the calculation of g factor in some covalent crystals containing trasition metal ions should use the two SO coupling parameter model but not the classical crystal field model including only the contribution from the SO coupling of central transition metal ions.
1992, 41 (7): 1182-1186. doi: 10.7498/aps.41.1182
Lead free single crystals of the ferrimagnetic garnet Bi3-2xCa2xFe5-x-yInyVxO12 are grown by using the flux method. High quality single crystals having a dimension greater than 10 mm and few inclusions can be obtained for all materials with different In content by the technology described in this paper. Faraday rotation and optical absorption of a single crystal with x≈ 0.90, y ≈ 0.12 were measured for wavelength in the range of 0.70 to 2.2 ≈m. In spite of the remarkable increase of rotation by the bismuth substitution, no appreciable increase of absorption coefficient is observed in this wavelength region. Our results demonstrated lead free single crystals of In-BCVIG synthesized in x≈ 1.0 composition region with small amount of In substitution are a magneto-optical material with hige value of magneto-optical figure of merit. Considering its low and variable magnetization, high Curie temprature and rather large magneto-optical rotation, the above results show that the crystals can be employed in magneto-optical devices.
1992, 41 (7): 1187-1195. doi: 10.7498/aps.41.1187
We present a unique theoretical model to describe the Raman soliton-like pulses in single-mode fibers and consider the existence of the group velocity dispersion (GVD), the stimulated Raman scattering (SRS), the self-phase modulation (SPM), the cross-phase modulation (XPM) and the fiber loss. The experiment made by Gouveianeto et al. is simulated and 84fs Raman soliton-like pulses are obtained in agreement with the experimental results. A distinct image of the evolution of Raman soliton-like pulses is abtained and some new ideas are put forward.
1992, 41 (7): 1196-1203. doi: 10.7498/aps.41.1196
Fundamental and higher order linear Raman scattering of J-aggregated 2,2′-cyanine adsorbed on the silver colloid has been analyzed on the basis of its concentration dependence. The results indicate that there exists only one kind of stable a-dsorbed J-aggregate structure. Some of the low-frequency bands in Raman spectrum are mainly due to J-aggregated molecule, which also plays an important role in the enhancement of higher order linear Raman scattering.
Interaction between the rough surface of InP and LB thin film of CuPc have been studied, and the reversible structure phase transition are found at room temperature and liquid nitrogen temperature, respectively.
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
1992, 41 (7): 1208-1212. doi: 10.7498/aps.41.1208
The samples of Sn4+ zeolite are obtained by cation exchange between natural zeolite and SnCl4, and then treated at different Temperatures (70-1000℃). By using Mossbauer spectroscopy, X-ray diffraction and infra-red spectroscopy, we studied the change of position of Sn4+ in the zeolite structure with the temperature. The results show that the Sn4+ is situated in the main duct (channel) of the zeolite structure, but with the increase of the temperature the zeolite is dehydrated gradually, then the Sn4+ begins to move from the center of the duct to the walls of the duct, consequently, owing to the increase of the asymmetry of the electric field where the Sn4+ is situated, the quadruple splitting increases with the increase of the temperature. At the same time the SnO2 component increases with the increase of temperature. When heat-treatment temperature reached 1000℃ the long range order structure of zeolite may be destroyed completely.