Table of contents

20 March 1995, Volume 4 Issue 3 Previous issue    Next issue

GENERAL

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THE POWER SPECTRUM OF THE MASS IN A SANDPILE MODEL WITH STOCHASTIC SLIDE OUYANG HUA-FU (欧阳华甫), HUANG ZU-QIA (黄祖洽), DING E-JIANG (丁鄂江) Acta Physica Sinica (Overseas Edition), 1995, 4 (3):  161-168.  DOI: 10.1088/1004-423X/4/3/001 Abstract ( 1162 )   PDF (237KB) ( 380 )   The power spectrum of the mass in a theoretical sandpile model with stochastic slide is examined. The simulations show that the power spectrum has the form of l/f$\alpha$, and the exponent $\alpha$ may vary with the average time interval (T) between the successive events af the sands flowing off the sandpile. The conditions of generating 1/f noise are also discussed.

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CONFORMAL INVARIANCE AND THE LANCZOS METHOD STUDIES OF A SPINNING QUANTUM CHAIN ZHANG HAI-YAN (张海燕), MA HONG-RU (马红孺), XU BO-WEI (许伯威) Acta Physica Sinica (Overseas Edition), 1995, 4 (3):  169-174.  DOI: 10.1088/1004-423X/4/3/002 Abstract ( 1086 )   PDF (136KB) ( 520 )   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 $\chi$ and the normalising factor $\xi$ are obtained from the energy spectrum. Also a simple derivation of the field theory of the model is given.

ATOMIC AND MOLECULAR PHYSICS

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TIME DECAY BEHAVIOR OF FULLERENE-C60 STUDIED BY TIME-RESOLVED PHOTOLUMINESCENCE SONG JIE (宋捷), LI FEI-MING (李飞鸣), QIAN SUI-XIONG (钱士雄), LI YU-FEN (李郁芬), PENG WEN-JI (彭文基), ZHOU JIAN-YING (周建英), YU ZHEN-XIN (余振新) Acta Physica Sinica (Overseas Edition), 1995, 4 (3):  175-182.  DOI: 10.1088/1004-423X/4/3/003 Abstract ( 1021 )   PDF (233KB) ( 387 )   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 $\tau$1 = 0.087ns, $\tau$2= 0.68 ns. Two relaxation mechanisms are given tentatively in explaining this phenomenon.

CLASSICAL AREAS OF PHENOMENOLOGY

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A SCHEME FOR OBTAINING HIGH GAIN-LENGTH PRODUCT IN RECOMBINATION X-RAY LASER BY USING A LOW DENSITY TARGET PENG HUI-MIN (彭惠民) Acta Physica Sinica (Overseas Edition), 1995, 4 (3):  183-193.  DOI: 10.1088/1004-423X/4/3/004 Abstract ( 1000 )   PDF (284KB) ( 336 )   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.

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COMPETITION BETWEEN SELF-PUMPED AND MUTUALLY-PUMPED PHASE CONJUGATIONS IN A BaTiO3 BRIDGE PHASE CONJUGATOR LIAN YING-WU (廉英武), YE PEI-XIAN (叶佩弦) Acta Physica Sinica (Overseas Edition), 1995, 4 (3):  194-203.  DOI: 10.1088/1004-423X/4/3/005 Abstract ( 1040 )   PDF (252KB) ( 410 )   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.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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MORPHOLOGY-STRUCTURE OF ORIENTED NONCRYSTALLINE POLYESTER STUDIED BY TWO-DIMENSIONAL WIDE ANGLE X-RAY SCATTERING CHEN JI-ZHOU (陈济舟), WANG JUN-QIAO (王俊桥), HAN FU-TIAN (韩甫田) Acta Physica Sinica (Overseas Edition), 1995, 4 (3):  204-212.  DOI: 10.1088/1004-423X/4/3/006 Abstract ( 911 )   PDF (264KB) ( 319 )   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.

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INTERACTION OF OXYGEN PRECIPITATES WITH STRUCTURAL DEFECTS IN CZ Si CRYSTALS LUAN HONG-FA (栾洪发), ZHANG JUN (张隽), XIAO ZHI-GANG (肖治刚), KE JUN (柯俊), Acta Physica Sinica (Overseas Edition), 1995, 4 (3):  213-218.  DOI: 10.1088/1004-423X/4/3/007 Abstract ( 896 )   PDF (208KB) ( 406 )   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.

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QUASI-KINEMATIC LOW-ENERGY ELECTRON DIFFRACTION AND ITS LATEST APPLICATIONS ZHAO RU-GUANG (赵汝光), HU CHUAN (胡川), ZHANG YUN (张云), JIA JIN-FENG (贾金锋), YANG WEI-SHENG (杨威生) Acta Physica Sinica (Overseas Edition), 1995, 4 (3):  219-224.  DOI: 10.1088/1004-423X/4/3/008 Abstract ( 1163 )   PDF (195KB) ( 326 )   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.

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

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ELECTRONIC STRUCTURE OF THE T*-TYPE SUPERCONDUCTORS (Bi0.5Sr1.5)(Y, Ce)2Cu2Oy STUDIED BY PHOTOELECTRON SPECTROSCOPY ZHANG YONG-JIAN (张永健), CHEN XIAN-HUI (陈仙辉), CAO LIE-ZHAO (曹烈兆), CHEN ZHAO-JIA (陈兆甲), ZHU JING-SHENG (朱警生) Acta Physica Sinica (Overseas Edition), 1995, 4 (3):  225-230.  DOI: 10.1088/1004-423X/4/3/009 Abstract ( 1141 )   PDF (173KB) ( 326 )   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+.