中国物理B

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STUDY OF FARADAY ANOMALOUS DISPERSION SPECTRA OF THE HYPERFINE STRUCTURE OF Rb D₂ LINES

彭玉峰, 汤俊雄, 王庆吉

1993 (1): 1-8. doi: 10.1088/1004-423X/2/1/001

摘要 ( 1241 )

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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

刘思敏, 张光寅, 严向军, 许京军, 纪卫星, 武原庆, 郭儒

1993 (1): 9-14. doi: 10.1088/1004-423X/2/1/002

摘要 ( 1181 )

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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

赵明信, 刘子东, 李丽云, 李森林, 吴正华, 曾锡之

1993 (1): 15-21. doi: 10.1088/1004-423X/2/1/003

摘要 ( 1162 )

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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.

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THE IMPURITY TRANSPORT IN HT-6B TOKAMAK

黄荣, 谢纪康, 李林忠, 何也熙, 汪舒娅, 邓传宝, 李国相, 魏乐汉, 邱励俭

1993 (1): 22-34. doi: 10.1088/1004-423X/2/1/004

摘要 ( 1137 )

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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.

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DISLOCATION DISSOCIATION ON CLIMB PLANE IN TEXTURED YBa₂Cu₃O_7-δ SUPERCONDUCTOR

郑建国, 李齐, 冯端

1993 (1): 35-41. doi: 10.1088/1004-423X/2/1/005

摘要 ( 1164 )

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Using high resolution electron microscopy, the structure of [100] tilt boundary with misorientation of 1.2° in YBa₂Cu₃O_7-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

胡承正, 丁棣华, 杨文革

1993 (1): 42-47. doi: 10.1088/1004-423X/2/1/006

摘要 ( 1203 )

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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

张仿清, 张文军, 张亚菲, 陈光华, 高巧君, 蒋翔六

1993 (1): 48-55. doi: 10.1088/1004-423X/2/1/007

摘要 ( 1128 )

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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.

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INVESTIGATION OF THE EFFECT OF SLOW NEUTRON IRRADIATION ON HALOGEN-DOPED HIGH-T_c SUPERCONDUCTORS AND ITS MECHANISM

金继荣, 金新, 吉和林, 张贻瞳, 徐小农, 施智祥, 张治平, 姚希贤, 庄瑞芳, 谢晖

1993 (1): 56-64. doi: 10.1088/1004-423X/2/1/008

摘要 ( 1063 )

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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 E_n>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-T_c YBaCuO AND GdBaCuO SUPERCONDUCTOR FILMS

江伟林, 郑宗爽, 朱沛然

1993 (1): 65-71. doi: 10.1088/1004-423X/2/1/009

摘要 ( 970 )

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Rutherford backscattering (RBS) measurements of 4.2 MeV Li and 2.4 MeV He ions were done for YBaCuO and GdBaCuO high-T_c, 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.

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