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1995年, 第4卷, 第3期　刊出日期：1995-03-20 上一期    下一期

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THE POWER SPECTRUM OF THE MASS IN A SANDPILE MODEL WITH STOCHASTIC SLIDE 欧阳华甫, 黄祖洽, 丁鄂江 1995 (3):  161-168.  doi: 10.1088/1004-423X/4/3/001 摘要 ( 1285 )   PDF(237KB) ( 400 )   相关文章 | 计量指标

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CONFORMAL INVARIANCE AND THE LANCZOS METHOD STUDIES OF A SPINNING QUANTUM CHAIN 张海燕, 马红孺, 许伯威 1995 (3):  169-174.  doi: 10.1088/1004-423X/4/3/002 摘要 ( 1230 )   PDF(136KB) ( 534 )   The low-lying energy spectrum of a spinning quantum chain in the critical region is calculated by using Lanczos method. According to conformal theory, the anomalous dimensions χ and the normalising factor ξ are obtained from the energy spectrum. Also a simple derivation of the field theory of the model is given. 相关文章 | 计量指标

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TIME DECAY BEHAVIOR OF FULLERENE-C60 STUDIED BY TIME-RESOLVED PHOTOLUMINESCENCE 宋捷, 李飞鸣, 钱士雄, 李郁芬, 彭文基, 周建英, 余振新 1995 (3):  175-182.  doi: 10.1088/1004-423X/4/3/003 摘要 ( 1139 )   PDF(233KB) ( 404 )   The time-resoved photoluminescence spectra of C60 have been studied from toluence solution at room temperature and from thin film at both room temperature and 77K. A photoluminescence peak at about 730nm was detected from solution at room temperature and film at 77K, in which lifetimes waz determined to be 1.1 and 0.9ns, respectively. At room temperature, the photoluminescence peak of thin film shifted to 740 nm with fast decay behavior which was fitted well to a double-exponential lifetimes with τ1 = 0.087ns, τ2= 0.68 ns. Two relaxation mechanisms are given tentatively in explaining this phenomenon. 相关文章 | 计量指标

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A SCHEME FOR OBTAINING HIGH GAIN-LENGTH PRODUCT IN RECOMBINATION X-RAY LASER BY USING A LOW DENSITY TARGET 彭惠民 1995 (3):  183-193.  doi: 10.1088/1004-423X/4/3/004 摘要 ( 1127 )   PDF(284KB) ( 357 )   A scheme for obtaining high gain-length product(GL) of recombination X-ray laser is proposed and theoretically studied, in which a thin fiber with a density less than the critical one is driven by a short pulse laser. The features of laser-produced plasma and the gain coefficients of the transition from n = 3 to n = 2 of the H-like ions for a solid fiber and a low-density cylindrical target of carbon are shown. The Sobolev escape probability in a self-similarly expanding cylindrical geometry is used to evaluate the trapping effect on the gain coefficient. According to the simulations there are three obvious advantages of the low-density target, ie., wider gain region, longer lasing duration and no drift of the gain region. In addition, only a few joules are needed for getting saturated GL value. 相关文章 | 计量指标

CLASSICAL AREAS OF PHENOMENOLOGY

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COMPETITION BETWEEN SELF-PUMPED AND MUTUALLY-PUMPED PHASE CONJUGATIONS IN A BaTiO3 BRIDGE PHASE CONJUGATOR 廉英武, 叶佩弦 1995 (3):  194-203.  doi: 10.1088/1004-423X/4/3/005 摘要 ( 1157 )   PDF(252KB) ( 423 )   This paper reveals the inter-dependence and the competition between self-pumped and mutually-pumped phase conjugations, and deals with the periodic instabilities in the phase conjugate output of a BaTiO3 bridge phase conjugator. It presents experimental data demon-strating these instabilities and also gives evidence that the addition of the second heam in a bridge phase conjugator can affect the self-pumping threshold for the first beam. A mathe-matical model is developed to explain the observed output oscillations. 相关文章 | 计量指标

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MORPHOLOGY-STRUCTURE OF ORIENTED NONCRYSTALLINE POLYESTER STUDIED BY TWO-DIMENSIONAL WIDE ANGLE X-RAY SCATTERING 陈济舟, 王俊桥, 韩甫田 1995 (3):  204-212.  doi: 10.1088/1004-423X/4/3/006 摘要 ( 1017 )   PDF(264KB) ( 337 )   Morphology-structure of oriented noncrystalline polyesters has been studied using the parameters changes of the broad peaks in wide angle X-ray scattering (WAXS) with azimuth angles. Twe-dimensional WAXS show that the oriented noncrystalline polyester is made up of long plane-like chains arranged in opposition to each other; and these chains are composed of oriented atomic distances with the chain axes parallel to the drawing direction and are closely arranged into lateral ordering. It is concluded that the arrangements of both interchain and intrachain distances are in good order in the oriented direction, while in other directions, they are arranged nearly at random. This shows that the oriented noncrystalline polymers are materials with their ordered structure varying with directions. 相关文章 | 计量指标

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INTERACTION OF OXYGEN PRECIPITATES WITH STRUCTURAL DEFECTS IN CZ Si CRYSTALS 栾洪发, 张隽, 肖治刚, 柯俊 1995 (3):  213-218.  doi: 10.1088/1004-423X/4/3/007 摘要 ( 1012 )   PDF(208KB) ( 429 )   This paper ia dealing with the interaction between oxygen precipitates and structural defects in CZ Si crystals. Different lattice defects: dislocation loops, rod-like defects and stacking faults have been observed as a consequence of oxygen precipitation. In turn, these defects also promote the nucleation and growth of the oxygen precipitates. It is shown that the dislocation dipole is more efficient than single dislocation in enhancing the oxygen precipitate formation. 相关文章 | 计量指标

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QUASI-KINEMATIC LOW-ENERGY ELECTRON DIFFRACTION AND ITS LATEST APPLICATIONS 赵汝光, 胡川, 张云, 贾金锋, 杨威生 1995 (3):  219-224.  doi: 10.1088/1004-423X/4/3/008 摘要 ( 1295 )   PDF(195KB) ( 340 )   In order to determine the structure of complex and/or stepped surfaces that are very difficult to or even beyond the capability of the full dynamic low-energy electron diffraction calculation, recently we have proposed the quasi-kinematic low-energy electron diffraction (QKLEED) approach and employed it to solve the structure of some important surfaces such as Si(111)-(31/2×31/2) R30°-Al and Si(111)-(31/2×31/2) R30°-Ag. In the present paper, following the highlights of QKLEED we give the latest application of it, i.e., the structural determination of the Si(111)-(31/2×31/2) R30°-Au, Si(111)-(31/2×31/2) R30°-Sn, and Pd(001)-c(2×2)-Mn surfaces. 相关文章 | 计量指标

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ELECTRONIC STRUCTURE OF THE T*-TYPE SUPERCONDUCTORS (Bi0.5Sr1.5)(Y, Ce)2Cu2Oy STUDIED BY PHOTOELECTRON SPECTROSCOPY 张永健, 陈仙辉, 曹烈兆, 陈兆甲, 朱警生 1995 (3):  225-230.  doi: 10.1088/1004-423X/4/3/009 摘要 ( 1284 )   PDF(173KB) ( 344 )   The electronic structure of T*-type compounds (Bi0.5Sr1.5)(Y2-xCex)Cu2Oy has been studied by X-ray photoelectron spectroscopy. From analysis of the results, it was found that cation deficiency in Ce4+ introduced holes to conduction planes in the T* phase as in the p-type infinite layer compounds. Some Cu ions in the sample without cation-deficiency contained two-oxygen coordination, which resulted in the incompleteness of the CuO2 sheets. Bi ions in the T* phase cuprates take exact valence of 3+, Pb ions cannot replace them due to the too large an ionic radius of Pb2+/Pb4+. 相关文章 | 计量指标