Table of Content

20 January 1993, Volume 2 Issue 1 Previous Issue    Next Issue

ATOMIC AND MOLECULAR PHYSICS

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STUDY OF FARADAY ANOMALOUS DISPERSION SPECTRA OF THE HYPERFINE STRUCTURE OF Rb D2 LINES PENG YU-FENG, TANG JUN-XIONG, WANG QING-JI 1993, 2 (1):  1-8.  doi: 10.1088/1004-423X/2/1/001 Abstract ( 0 )   PDF (167KB) ([an error occurred while processing this directive])   Natural rubidium is a mixture of the two isotopes, 85Rb and 87Rb, the natural abundances of which are 72.2 and 27.8 percent, respectively. Taking into account their hyperfine structure, we have cal-culated the Faraday anomalous dispersion spectra (FADS)of Rb D2 lines in different magnetic fields and observed them experimentally. The theoretical calculations are in good agreement with the experi-mental results. In this paper, we also discuss the results.

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A SINGLE-BEAM OPTICAL TRAP FOR AIR BUBBLES IN A LIQUID AND THE CHANGE OF THE OPTICAL FIELD LIU SI-MIN, ZHANG GUANG-YIN, YAN XIANG-JUN, XU JING-JUN, JI WEI-XING, WU YUAN-QING, GUO RU 1993, 2 (1):  9-14.  doi: 10.1088/1004-423X/2/1/002 Abstract ( 0 )   PDF (221KB) ([an error occurred while processing this directive])   We report a single-beam optical trap for particles with refractive index lower than that of the surrounding medium—the air bubbles in the liquid. This phenomenon is explained by radiation pressure.

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MEASUREMENTS OF RELAXATION OF SPIN POLARIZED 129Xe NUCLEI IN HIGH MAGNETIC FIELDS ZHAO MING-XIN, LIU ZI-DONG, LI LI-YUN, LI SEN-LIN, WU ZHENG-HUA, ZENG XI-ZHI 1993, 2 (1):  15-21.  doi: 10.1088/1004-423X/2/1/003 Abstract ( 0 )   PDF (166KB) ([an error occurred while processing this directive])   We observed the NMR signal of low-pressure gas 129Xe by laser enhanced method on an MSL-400 NMR spectrometer and measured nuclear spin relaxations of 129Xe gas at various temperatures. The relaxation rate constant of 129Xe-133Cs spin exchange was obtained as (6.8±0.5)×10-16cm-3s-1.

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

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THE IMPURITY TRANSPORT IN HT-6B TOKAMAK HUANG RONG, XIE JI-KANG, LI LIN-ZHONG, HE YE-XI, WANG SHU-YA, DENG CHUAN-BAO, LI GUO-XIANG, WEI LE-HAN, QIU LI-JIAN 1993, 2 (1):  22-34.  doi: 10.1088/1004-423X/2/1/004 Abstract ( 0 )   PDF (382KB) ([an error occurred while processing this directive])   The quasi-stationary profiles of the impurity ionization stages in HT-6B Tokamak were absolutely determined by monitoring the VUV and visible line emissions. An impurity transport code was set up. The impurity transport coefficients and other parameters about impurities were determined. From the changes of impurity emission profiles, it was concluded that the impurity confinement was improved and the impurity recycling was reduced by the slow magnetic compression along the minor radius. Some characteristics about the impurity transport in this small device are discussed.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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DISLOCATION DISSOCIATION ON CLIMB PLANE IN TEXTURED YBa2Cu3O7-δ SUPERCONDUCTOR ZHENG JIAN-GUO, LI QI, FENG DUAN 1993, 2 (1):  35-41.  doi: 10.1088/1004-423X/2/1/005 Abstract ( 0 )   PDF (285KB) ([an error occurred while processing this directive])   Using high resolution electron microscopy, the structure of [100] tilt boundary with misorientation of 1.2° in YBa2Cu3O7-δ has been determined. The boundary is shown to consist of an array of partial dis-locations, These partials result from the dissociation of a perfect dislocation with a Burgers vector [0, 0, c] on its climb plane according to the reaction, b→b1+b2+b1+b2+b1+b2. Here b=[00c], b1=[O,b/2, c/6} (or [a/2, 0, c/6] ). b2=[0, -b/2. c/6] (or[ -a/2, 0, c/6] ). The spacing between the perfect dislocations satisfies the Read-Shockley formula. There exist no amorphous phases in the boundary region.

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EXPRESSION OF THE ELASTIC ENERGY IN TWO-DIMENSIONAL QUASICRYSTALS HU CHENG-ZHENG, DING DI-HUA, YANG WEN-GE 1993, 2 (1):  42-47.  doi: 10.1088/1004-423X/2/1/006 Abstract ( 0 )   PDF (164KB) ([an error occurred while processing this directive])   The application of group theory to elasticity in two-dimensional (2D)quasicrystals is presented. The expression of elastic energy as a function of gradients of the phonon and phason fields has been derived to quadratic order. The phonon response to an external stress is isotropic, but the response of phason field is anisotropic for eightfold and twelvefold symmetries.

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GROWTH CHARACTERISTICS OF DIAMOND FILMS DEPOSITED ON Si AND W SUBSTRATES ZHANG FANG-QING, ZHANG WEN-JUN, ZHANG YA-FEI, CHEN GUANG-HUA, GAO QIAO-JUN, JIANG XIANG-LIU 1993, 2 (1):  48-55.  doi: 10.1088/1004-423X/2/1/007 Abstract ( 0 )   PDF (417KB) ([an error occurred while processing this directive])   Growth characteristics of diamond films synthesized by using a dc arc discharge plasma CVD were studied by means of XRD,SEM and reflection electron diffraction. The results showed that columnar growth of the diamond films was observed, the columns having an average diameter of about 15μm, with sharp and regular base edges. Diamond grains grows on the substrata were initially of uniform polygons. An interfacial transition layer of polycrystalline SiC was observed between the diamond film and Si substrate. Diamond grains grown during the early-stage on W substrate were also uniform, and an interfacial transition layer of polycrystalline WC was observed between the diamond film and the substrate.

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

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INVESTIGATION OF THE EFFECT OF SLOW NEUTRON IRRADIATION ON HALOGEN-DOPED HIGH-Tc SUPERCONDUCTORS AND ITS MECHANISM JIN JI-RONG, JIN XIN, JI HE-LIN, ZHANG YI-TONG, XU XIAO-NONG, SHI ZHI-XIANG, ZHANG ZHI-PING, YAO XI-XIAN, ZHUANG RUI-FANG, XIE HUI 1993, 2 (1):  56-64.  doi: 10.1088/1004-423X/2/1/008 Abstract ( 0 )   PDF (271KB) ([an error occurred while processing this directive])   Irradiation effect of low-fluence (-108 n/cm2 ) slow neutrons on halogen-doped superconductors is presented in this paper. And the mechanism of the effect is also described from the viewpoint of nuclear physics for both fast and slow neutrons on high-temperature superconductors (HTSC). It is shown ex-perimentally and theoretically that slow neutrons of low fluence has a similar irradiation effect to that of fast neutron beams with an energy En>0.1 MeV and fluence 1016-1018 n/cm2-However,quite differ-ent mechanisms are involved in them: Fast neutrons transfer their energies through elastic scattering in HTSC, whereas slow neutrons give off their energies during the slow neutron capture (n,γ) reaction.

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Li ION BACKSCATTERING STUDY ON HIGH-Tc YBaCuO AND GdBaCuO SUPERCONDUCTOR FILMS JIANG WEI-LIN, ZHENG ZONG-SHUANG, ZHU PEI-RAN 1993, 2 (1):  65-71.  doi: 10.1088/1004-423X/2/1/009 Abstract ( 0 )   PDF (162KB) ([an error occurred while processing this directive])   Rutherford backscattering (RBS) measurements of 4.2 MeV Li and 2.4 MeV He ions were done for YBaCuO and GdBaCuO high-Tc, superconductor films deposited on MgO and SrTiO3 single crystalline substrates and for their bulk samples. Energy spectra of both ions were calculated using the RBS analysis program rewritten by the authors. Comparisons between these two non-destructive tech-niques showed some advantages in analyzing the layer thickness and composition ratios of those thin films by MeV Li ions backscattering. Estimated errors are within 7 % for the measured elemental con-centrations and l0 % for the layer thickness in our experiments. A brief discussion is also made of the results.