中国物理B

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STUDY OF A (2+1)-DIMENSIONAL BROER-KAUP EQUATION

阮航宇, 陈一新

1998 (4): 241-248. doi: 10.1088/1004-423X/7/4/001

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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

耿文通, 段一士

1998 (4): 249-257. doi: 10.1088/1004-423X/7/4/002

摘要 ( 1229 )

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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.

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RELATIVISTIC MEAN-FIELD APPROACHES FOR LIGHT HYPERNUCLEI

沈姚崧, 任中洲

1998 (4): 258-270. doi: 10.1088/1004-423X/7/4/003

摘要 ( 1037 )

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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.

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MULTIPHOTON IONIZATION MASS SPECTRA OF n-C₃H₇I AND i-C₃H₇I AT 532 nm

章莲蒂, 魏杰, 姜芸芸, 方黎, 张树东, 郭文跃, 蔡继业

1998 (4): 271-276. doi: 10.1088/1004-423X/7/4/004

摘要 ( 1333 )

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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

董晨钟, 王建国, 屈一至

1998 (4): 277-282. doi: 10.1088/1004-423X/7/4/005

摘要 ( 1103 )

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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 .

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MULTIFACTORIAL ORTHOGONAL DECISION ON DIFFRACTION EFFICIENCY OF FRESNEL HOLOGRAM

许蕾, 张肇群, 彭晓原

1998 (4): 283-287. doi: 10.1088/1004-423X/7/4/006

摘要 ( 1057 )

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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.

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SELF-MAGNETIC-FIELD-LIMITING CURRENT OF INTENSE RELATIVISTIC ELECTRON BEAM UNDER EXTERNALLY APPLIED MAGNETIC FIELD

刘国治, 宋晓欣

1998 (4): 288-291. doi: 10.1088/1004-423X/7/4/007

摘要 ( 1246 )

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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.

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PINNING EFFECT OF LEAD LANTHANUM TITANATE THIN FILMS DEPOSITED ON DIFFERENT SUBSTRATES

宋志棠, 任巍, 张良莹, 姚熹

1998 (4): 292-307. doi: 10.1088/1004-423X/7/4/008

摘要 ( 1049 )

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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.

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