Table of contents

20 April 1998, Volume 7 Issue 4 Previous issue    Next issue

GENERAL

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STUDY OF A (2+1)-DIMENSIONAL BROER-KAUP EQUATION RUAN HANG-YU (阮航宇), CHEN YI-XIN (陈一新) Acta Physica Sinica (Overseas Edition), 1998, 7 (4):  241-248.  DOI: 10.1088/1004-423X/7/4/001 Abstract ( 1152 )   PDF (200KB) ( 458 )   The Painlevé property and infinitely many symmetries of a (2+1)-dimensional Broer-Kaup equation which is obtained from the constraints of the KP equation are studied in this paper. The Painlevé property is proved by the Weiss-Kruskal approach, the infinitely many symmetries are obtained by the formal series symmetry method.

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SPACE-TIME TORSION AND THE QUANTIZATION OF SPIN GENG WEN-TONG (耿文通), DUAN YI-SHI (段一士) Acta Physica Sinica (Overseas Edition), 1998, 7 (4):  249-257.  DOI: 10.1088/1004-423X/7/4/002 Abstract ( 1229 )   PDF (234KB) ( 435 )   It is shown that within the framework of the Einstein-Cartan-Sciama-Kibble theory, space-time torsion could account for the quantization of the spin angular momentum of Dirac particles.

NUCLEAR PHYSICS

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RELATIVISTIC MEAN-FIELD APPROACHES FOR LIGHT HYPERNUCLEI SHEN YAO-SONG (沈姚崧), REN ZHONG-ZHOU (任中洲) Acta Physica Sinica (Overseas Edition), 1998, 7 (4):  258-270.  DOI: 10.1088/1004-423X/7/4/003 Abstract ( 1038 )   PDF (325KB) ( 358 )   We study the ground state properties of light hypernuclei theoretically using the relativistic mean-field theory with TM1 and NL-SH force parameters. It is found that these new parameters can satisfactorily reproduce the ground state properties of the light hypernuclei even near the neutron drip-line. The parameter sets TM1 and NL-SH give a very similar description of hypernuclei. The properties of hypernuclei in baryon-hyperon systems are insensitive to the force parameters of effective nucleon nucleon interactions. We also take into account the influence of pairing forces on the Λ hyperon and find that it leads to an even-odd effect in light hypernuclei.

ATOMIC AND MOLECULAR PHYSICS

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MULTIPHOTON IONIZATION MASS SPECTRA OF n-C3H7I AND i-C3H7I AT 532 nm ZHANG LIAN-DI (章莲蒂), WEI JIE (魏杰), JIANG YUN-YUN (姜芸芸), FANG LI (方黎), ZHANG SHU-DONG (张树东), GUO WEN-YUE (郭文跃), CAI JI-YE (蔡继业) Acta Physica Sinica (Overseas Edition), 1998, 7 (4):  271-276.  DOI: 10.1088/1004-423X/7/4/004 Abstract ( 1333 )   PDF (167KB) ( 346 )   Multiphoton Ionization (MP) Mass Spectra of n-C3H7I AND i-C3H7I are obtained using a time-offlight mass spectrometer at 532 nm. No parentions are observed in MPI of both isomers. N-propyl cation dissociates more extensively than isopropyl cation. The C2H+5(M/Z=29) ion is observed instead of C2H+4(M/Z=28) ion in MPI of n-C3H7I, in contrast to i-C3H7I. It is found that parent molecules are first two-photon resonantly excited to A-band, then go through dissociation. Fragment ions are produced by ionization and dissociation of neutral fragments. We present directly the diss ociation pathways of n-propyl cation according to the results proposed by Levine using maximum entropy formalism. Moreover, those of isopropyl cation are discussed in this paper through branching ratio analyses.

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RESONANCE CONTRIBUTION TO 1s-2s ELECTRON-IMPACT EXCITATION OF He+ ION DONG CHEN-ZHONG (董晨钟), WANG JIAN-GUO (王建国), QU YI-ZHI (屈一至) Acta Physica Sinica (Overseas Edition), 1998, 7 (4):  277-282.  DOI: 10.1088/1004-423X/7/4/005 Abstract ( 1106 )   PDF (166KB) ( 376 )   In the frame of quantum defect theory, the resonance excitation cross sections of 1s-2s electron-impact excitation of He+ ion are calculated by a simple relativistic configuration interaction method. The present theoretical results are in agreement with the previous experimental measurements .

CLASSICAL AREAS OF PHENOMENOLOGY

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MULTIFACTORIAL ORTHOGONAL DECISION ON DIFFRACTION EFFICIENCY OF FRESNEL HOLOGRAM XU LEI (许蕾), ZHANG ZHAO-QUN (张肇群), PENG XIAO-YUAN (彭晓原) Acta Physica Sinica (Overseas Edition), 1998, 7 (4):  283-287.  DOI: 10.1088/1004-423X/7/4/006 Abstract ( 1057 )   PDF (136KB) ( 346 )   The method of multifactorial orthogonal decision on diffraction efficiency (DE) of Fresnel hologram is proposed in this paper. The orthogonal table is designed for such major manufacturing parameters as beam ratio, expo sure, development time and developer density. With variance analysis, the conspicuous factors on DE are obtained, and the optimal technological conditions are established. In addition, by regression analysis to the conclusion, we obtain a fit rate of about 88% to the calculated and experimental results.

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

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SELF-MAGNETIC-FIELD-LIMITING CURRENT OF INTENSE RELATIVISTIC ELECTRON BEAM UNDER EXTERNALLY APPLIED MAGNETIC FIELD LIU GUO-ZHI (刘国治), SONG XIAO-XIN (宋晓欣) Acta Physica Sinica (Overseas Edition), 1998, 7 (4):  288-291.  DOI: 10.1088/1004-423X/7/4/007 Abstract ( 1246 )   PDF (107KB) ( 409 )   The self-magnetic-field-limiting current of intense relat ivistic electron beam (IREB) without an externally applied magnetic field is reported and briefly commented in this paper. By using dynamic balance method the self-magnetic-field-limiting current of IREB under externally applied magnetic field is derived, showing that in this case it will increase. This result is obtained for the first time, so far as we know, and will be further tested by experiment.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

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PINNING EFFECT OF LEAD LANTHANUM TITANATE THIN FILMS DEPOSITED ON DIFFERENT SUBSTRATES SONG ZHI-TANG (宋志棠), REN WEI (任巍), ZHANG LIANG-YING (张良莹), YAO XI (姚熹) Acta Physica Sinica (Overseas Edition), 1998, 7 (4):  292-307.  DOI: 10.1088/1004-423X/7/4/008 Abstract ( 1049 )   PDF (521KB) ( 442 )   Pinning effect of lead lanthanum titanate (PLT) ferroelectric thin films with excess PbO of 20 mol% has been studied for deposition on diffe rent substrates. Silicon, sapphire and quartz were used as substrates on which P t/Ti or LaNiO3 thin films were deposited as bottom electrodes. Electron probe analysis results showed that there was still a certain amount of excess Pb in PLT films after annealing at 550 ℃ for 1 h, and the amount of it was dependent on the substrate used. The distribution of excess Pb in the films was investig ated by Auger electron spectroscopy depth profile. It was shown that the substrates and the bottom electrodes had significant effects on the content and distrib ution of excess Pb in PLT films. The excess Pb and its accumulation at the inter face between the film and bottom electrode may act as pinning centers and have a pinning effect on domains, which can be observed by abnormal P-E hysteresis loops and abnormal C-V curves. The excess Pb content in the films and the accumulation of Pb at the interface were high in PLT films deposited on Pt/Ti/S i, and considerable pinning effect was observed. As LaNiO3 would absorb most part of the excess Pb in PLT films, the content of excess Pb in the films deposited on LaNiO3/Si was very low and the pinning effect was hardly observed.