Vol. 40, No. 4 (1991)
1991-02-20
GENERAL
1991, 40 (4): 505-512.
doi: 10.7498/aps.40.505
Abstract +
In terms of the theory of nonlinear connection, we proposed the concept of Beltrami connection in two dimension space, and discussed the symmety of Polyakov's two dimension gravty.
1991, 40 (4): 513-521.
doi: 10.7498/aps.40.513
Abstract +
By means of some limiting procedures, the solutions of a complex nonlinear equation with many parameters could degenerate into the solutions of a simple equation with less parameters. In this paper, taking KdV equation and high order KdV equations as example, we analyse the possibility of the inverse procedure of the limiting process mentioned above. The results show that deforming a solution of a simple equation into that of the. complex equations is possible. However, this inverse procedure is not unique in general.
NUCLEAR PHYSICS
1991, 40 (4): 522-526.
doi: 10.7498/aps.40.522
Abstract +
We describe a new technique for MeV heavy-ion backscattering analysis of trace heavy elements on the surface and near surface. Pulse pileup problems are eliminated by choice of incidence ion mass M1, which is the same as or larger then that of bulk atom M2. Using 3 MeV Si beam, we could measure quantities of arsenic implanted in silicon down to 2×1012 atoms/cm2. Experimental results also show that sensitivity for impurity element on silicon substrate is as high as 2.2 ×109 atoms/cm2 for Au.
ATOMIC AND MOLECULAR PHYSICS
1991, 40 (4): 527-532.
doi: 10.7498/aps.40.527
Abstract +
On the basis of impulse approximate method, an analytical wavefuction based on a potential model was used to calculate the l-mixing transition cross section of Rydberg state Na atom in thermal collision with He, Ne and Ar, the results for Na-He are better than that of other methods ever used.
1991, 40 (4): 533-540.
doi: 10.7498/aps.40.533
Abstract +
In this paper, we introduce the binomial state of a two-level atomic system, which is a state that yields a binomial probability distribution. Its generation, squeezing, antibunching, and subpoisson statistics are discussed. It reduces to the Glauber coherent state in certain limit, and in that limit, the binomial distribution reduces to the Poisson distribution. This limiting process destroys all nonclassical effects of the system. The Bloch vector model is used to discuss the quantum characters of mixed state of one atom. Finally, the binomial state of the atomic system and the binomial state of the Bose system is compared. It is shown that the binomial state of a Bose system can not be produced in a atomic system.
1991, 40 (4): 541-546.
doi: 10.7498/aps.40.541
Abstract +
The abnormal changes in SERS of salicylic acid adsorbed on colloidal silver caused by adding KC1 are reported in this article. It was found that the SERS of some vibrational modes corresponsing to certain structures in salicylic acid were reduced rapidly. However, only the SERS intensity of v(-OH) vibration near 3436cm-1 incresed further because of KC1 addition. Also the influence of adding KC1 on SERS signals of a series of molecules including -COOH structure such as p-aminobenzoic acid, benzoic acid etc., were investigated. It was shown that Cl- could obviously weaken the SERS intensity of those molecules adsorbed on silver colloid. Both the phenomena have been discussed, and were compared with the case of pyriline. The results of transmission electron micriscopy observation and UV-visible spectral. experiments showed the agreement with the above conclusion.
CLASSICAL AREA OF PHENOMENOLOGY
1991, 40 (4): 547-554.
doi: 10.7498/aps.40.547
Abstract +
Based on the reference [1] , the mathematical and quantum statistical properties of the orthonormalized eigenstates of operator αk (k=3) are studied in this paper. It is found that all the orthonormalized eigenstates have nonclassical effects and they form a nonclassical complete representation. The result given by the reference [1] in the case k = 3 is only a special instance of the general conclusion of ours.
1991, 40 (4): 555-559.
doi: 10.7498/aps.40.555
Abstract +
A model is presented for the transmission spectra calculation of an atom-cavity. The three peaks structure of the spectra obtained can be regarded as the result of vacuum Rabi oscillation.
1991, 40 (4): 560-567.
doi: 10.7498/aps.40.560
Abstract +
This paper presents the effects of electron irradiation on the characteristics of single mode optical fibers doped with rare earth Er3+. The parameters of optical fibers are measured, prior to irradiation and after irradiation and annealing. It has been found that absorption loss in the wave length range of 0.80-1.60 μm is greatly lager than those of unirradiationed fibers. The irradiation induced loss obeys the following exponential laws: LUV =0.342exp [E(eV)/0.166] in the range of 0.80-1.20 urn and LIR = 2.2×104exp [-6.08E(eV)] in the range of 1.20-1.60 μm range. During annealing, the induced loss at longer wave length decreases, but that near 0.80 μm increases. Finally, the paper discusses the mechanism of loss variations. The displaced probability of oxygen and silicon atoms in electron irradiation is estimated to be 7.1×10-8 and 3.9×l0-8, respectively. The loss induced by displaced atoms is 200 times langer than that induced by the same amount of OH- at 1.40 μm. The process of annealing of the loss essentially occurs in two steps, i.e., by neutralization of the free electron and reforming of the broken bonds.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
1991, 40 (4): 568-574.
doi: 10.7498/aps.40.568
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This paper studies the nearly degenerate four-wave mixing in plasma which is caused by the electron plasma wave excited via the process of stimulated Raman scattering. The third-order nonlinear susceptibilities of the plasma are derived analytically and the condition to satisfy the phase matching is discussed. The couple-wave equations are solved to obtain the phase conjugate reflectivity. The dependence of the reflectivily on the frequency difference between the pump and the probe beam as well as on the interaction length is studied both analytically and numerically.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1991, 40 (4): 575-583.
doi: 10.7498/aps.40.575
Abstract +
In this paper we analyze and discuss the characteristics of internal friction of metallic glasses near glass transition temperature Tg based on the model of free volume and mechanical theory of solids. The relationship between stress and strain was obtained if the proportion occupied by solid-like and liquid-like regions in the matrix of glassy state was considered. It is found theoretically that the internal friction peak being of relaxation type can appear in the vicinity of Tg and the modulus decrease dramatically during glass transition. The theoretical analysis is essentially in agreement with experimental results.
1991, 40 (4): 584-587.
doi: 10.7498/aps.40.584
Abstract +
The correlation dimensions of correlation clusters at the critical point of continuous phase transformation are studied. The correlation dimensions Dn= d-nβ/(n - l)v, the dimension of one cluster a = d-β/v and the dimension of the centres of cluster f(a)=d are derived rigorously, and their meanings are discussed.
1991, 40 (4): 588-595.
doi: 10.7498/aps.40.588
Abstract +
Kinetics of (Ba1-xPbx) TiO3 solid solution formation was studied by high-temperature X-ray diffraction. The relations among the concentration of lead and the reaction rate constant K, as well as activation energy Q and the kinetic parameter C are discussed.
1991, 40 (4): 596-603.
doi: 10.7498/aps.40.596
Abstract +
Ionic conductivity and activation energy of 60 meshpowder, 120 mesh-powder, 200 mesh-powder, tablet pressed with powder and bulk piece of amorphous lithium ionic conductor P2O5-0.7Li2O-0.4LiCl-0.1Al2O3 in the range of 60℃-380℃ were investigated. It is found that decreasing the grain size can enhance ionic conductivity by 4 times and does not affect activation energy, owing to the effect of boundary layer in the same amorphous phase. Research after ionic conductivity measurement and X-ray diffraction of samples heated at 380℃ for 76 hours show that following the grain size becomes smaller, the crystallization process becomes easier. The bulk piece of amorphous sample not only has conductivity two orders higher than that of the tablet sample and lower activation energy, but also is more difficult to crystallize. Hence it possesses higher applicability. Study on DSC, conductivity, XRD and DTA of 60 mesh, 120 mesh, 200 mesh amorphous powder heated at 300℃ for 330 hours and at 350℃ for 612 hours shows that there are more than two amorphous phases and more complex interface effects among different phases in their amorphous phase separation.
1991, 40 (4): 604-609.
doi: 10.7498/aps.40.604
Abstract +
The influence of coadsorbed alkali metal on the electronic structure of CO was studied by ARUPS with polarized and unpolarized light. A new peak at 6.3 eV was observed, it reflects a new orbital of CO with the presence of coadsorbed alkali atoms. A symmetry plane and an anti-symmetry plane for this orbital were found, which are paralell to the 〈001〉azimuth and 〈110〉azimuth of the crystal surface respectively. The symmetry results of CO coadsorbed with different kinds of alkali metal are the same.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1991, 40 (4): 610-615.
doi: 10.7498/aps.40.610
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The influence of the nonparabolicity of band structure on Fr?hlich polarons is studied theoretically. The model used applies a simplified two-band approximation. Nonparabolicity is found to affect both the polaronic binding energy and the effective-mass renormalization. Comparing with the earlier theories, in addition to band nonparabolicity, we have considered the polaron effects. The theory presented in this paper agrees well with experimental results.
1991, 40 (4): 616-624.
doi: 10.7498/aps.40.616
Abstract +
A simplified "five vacant hybrid orbital" model is proposed for the boron-vacancy complex, and the defect wave function are calculated using an empirical tight binding Green function method under extended defect potential approximation. The calculated hyperfine interaction constants of the nearest neighbors of the vacancy and the probability distribution of defect wave function localized at atomic distants from the vacancy, are in good agreement with the electron-nuclear double-resonance experiment. The deep energy obtained is comparable with the value measured by deep-level transient-spectroscopy. The theoretical results provide a strong support to the conclusion that boron atom is located at the lattice position next to the vacancy and the defect is a B-V+ charge state.
1991, 40 (4): 625-629.
doi: 10.7498/aps.40.625
Abstract +
Coadsorption of CO and K on Cu(lll) surface was investigated using a Kelvin probe. We found that CO can adsorb (probably dissociatively) on the potassium precovered Cu(lll) surface at room temperature. When θKmin, (θmin = 0.18) the adsorption of CO makes the work function increase. When θK>θmin, the work function decreases at first, and then increases with amount of CO exposure. The results can be well accounted for by the jellium slab model.
1991, 40 (4): 630-633.
doi: 10.7498/aps.40.630
Abstract +
The preparing method of (BiPb)-Sr-Ca-Cu-O 2223 phase high-Tc superconductor is introduced. The magnetic relaxation rate dependence on applied magnetic field was measured by using a vibrating sample magnetometer. From the above results, the relationship of activation energy U0 vs. applied magnetic fuild B is discussed. We found that the functional form is U0-B-a in the magnetic field range of 0-0.23 T. The results is similar with that of Pa-lstra based on resistance broadening experiment for single crystals.
1991, 40 (4): 634-641.
doi: 10.7498/aps.40.634
Abstract +
Transport critical current density Jc and hysteresis loop at different field-sample orientations were measured for both melt-textured growth (MTG) and sintered YBa2Cu3Oy (YBCO) sample. Very high Jc (78K, 0 Oe) of 3.5×104A/cm2 has been obtained for the MTG YBCO sample. The experimental results show strong evidence of that the high Jc in MTG YBCO results mainly from the significant reduction of weak links because the bulk Jc for MTG sample are almost the same as the intragrain Jc for sintered sample. We also show that the Jc parallel to a-b plane is about an order of magnitude higher than that normal to a-b plane(Jc∥≈10Jc⊥).
1991, 40 (4): 642-645.
doi: 10.7498/aps.40.642
Abstract +
Superconducting single crystals of Bi-Sr-Ca-Cu-O 2212 phase have been sucessfully grown by a directional solidification method. The maximum size of single crystal reached 19+3×mm3. The (001) plane of the crystals is parallel to the growth direction. The crystals tend to grow along the [010] direction. Back-reflection Laue pattern revealed that the large crystal is indeed one single crystal. Measurements of electrical resistivity and ac susceptibility showed that Tc(zero) of the single crystals annealed in O2 was 81.5 K.
1991, 40 (4): 646-652.
doi: 10.7498/aps.40.646
Abstract +
The strong periodic surface electric strength caused by spontaneous polarization may be used as an undulator instead of Wiggler magnet to produce free electron laser. But the free electrons falling on it screen the potential gradually.Some screen-relif measures are proposed in this paper. Every positive polarized domain on the polarized crystal surface of LiNbO3 is covered with a piece of insulator film and covered further with an earthed conductor film to protect this polarized crystal surface from electric screening by free electrons. It is proved that the sum of induced charges on two surfaces of each part in these conductor films is zero. The free electrons falling on it will escape into the Earth at once.
1991, 40 (4): 653-658.
doi: 10.7498/aps.40.653
Abstract +
Bi substitute DyIG thin films having high coercive force and good squareness have been prepared on glass substrates by sputtering. The Faraday rotation amounts to about 7.5°/μm at wavelength of 500 nm. The magnetic domains are stable after thermal magnetic recording. The interference of magnetooptical thin films is investigated when the surface of films is deposited with different metals. Using this charecteristics the optimum disign for garnet recording discs can be achieved.
1991, 40 (4): 659-666.
doi: 10.7498/aps.40.659
Abstract +
In this paper, the effects of the incidence angle of the ion-bombardment on the puttering parameters ire investigated by using Monte Carlo simulation based on the binary collision approximation. The dependence of sputtering yields, energy and angular distribution as well as threshold energy of sputtered particles on incidence angle are discussed. The results of calculation are compared with data given by semi-empirical formula and measurments.
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
1991, 40 (4): 667-672.
doi: 10.7498/aps.40.667
Abstract +
The vibration modes of hydrogen-atom adsorption on the diamond surface were studied with high resolution-electron energy loss spectroscopy. Two main losses were observed at 360 meV and 160 meV. They are assigned to the C-H stretch vibrations and the angle-changing deformation vibrations respectively. Replacing H-atom with D-atom, isotropic shifts were observed in the loss spectra. Heating the diamond surface to 900℃, all of the loss features disappear, but an inelastic continuous loss-structure was observed. Due to H-atom desorp-tion, the dangling-bonds became horizontal bonds on the diamond surface, resulting in the gra-phitization of diamond surface. The appearance of the inelastic continuous loss-structure was the characteristic of graphite π-band. The graphitization of the diamond surface was affirmed further by UPS and AES studies.
