Table of contents

15 January 1999, Volume 8 Issue 1 Previous issue    Next issue

GENERAL

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BERRY PHASES IN THE QUANTUM STATE OF THE ISOTROPIC HARMONIC OSCILLATOR WITH TIME-DEPENDENT FREQUENCY AND BOUNDARY CONDITIONS Liu Deng-yun (刘登云) Acta Physica Sinica (Overseas Edition), 1999, 8 (1):  1-7.  DOI: 10.1088/1004-423X/8/1/001 Abstract ( 1272 )   PDF (194KB) ( 465 )   The problem of the isotopic harmonic oscillator of time-dependent frequency confined in a spherical box with time-dependent radius is studied. We show that the exact solution and the Lewis invariant operator can be obtained by performing two consecutive gauge transformations on the time-dependent Schr$\ddot{\rm o}$dinger equation. On the basis of the exact solution the non-adiabatic Berry phases for the system are calculated.

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VECTOR LADDER OPERATORS FOR THE CENTRAL POTENTIALS Ni Zhi-xiang (倪致祥) Acta Physica Sinica (Overseas Edition), 1999, 8 (1):  8-13.  DOI: 10.1088/1004-423X/8/1/002 Abstract ( 1147 )   PDF (177KB) ( 1575 )   A new class of nonlinear Lie algebra has been found, which is generated naturally by the Hamiltonian operator, the square of the angular momentum operator and the ladder operator for the central potentials. According to the theory of nonlinear Lie algebra, without using the factorization method, we obtained the vector ladder operators for the three-dimensional isotropic harmonic oscillator and hydrogen atom. The radial components of these operators, which are independent of the quantum numbers, are just the radial ladder operators for the same potentials.

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DOMAIN STRUCTURES AND ANISOTROPY IN Pt1-xCux/Co MULTILAYER THIN FILMS Xu Hai (徐海), Han Bao-shan (韩宝善), Ma Ping-ping (马平平), Zheng Wu (郑鹉), Chen Jin-chang (陈金昌) Acta Physica Sinica (Overseas Edition), 1999, 8 (1):  14-20.  DOI: 10.1088/1004-423X/8/1/003 Abstract ( 1404 )   PDF (446KB) ( 386 )   The domain structures of Pt1-xCux/Co multilayer films in as-grown and remanent states have been investigated by using magnetic force microscope. The magnetic domain patterns are strongly influenced by the Cu concentration. For pure Pt/Co multilayer in as-grown state, its domain pattern is depicted as island-like one; however, with the Cu doped in Pt spacer layers, the doman patterns become dot-like, but the island-like domain pattern appears again for the Cu concentration of 14 at%. The domain patterns variation can be attributed to the change of effective perpendicular anisotropy Kueff due to the effect of Cu atom doped in the Pt spacer layers. Besides, the domain structures of Pt/Co multilayer films in remanent state after the application of various perpendicular magnetic fields have also been studied.

NUCLEAR PHYSICS

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THE SEPARATION TECHNIQUES FOR SECONDARY BEAMS AT RIBLL Guo Zhong-yan (郭忠言), Zhan Wen-long (詹文龙), Liu Guan-hua (刘冠华), Sun Zhi-yu (孙志宇), Xiao Guo-qing (肖国青), Jiang Shan-hong (江山红), Li Jia-xing (李家兴), Wang Jin-chuan (王金川), Meng Xiang-wei (孟祥伟), Zhang Wan-sheng (张万生), Qin Li-jun (秦礼军), Wang Quan-jin (王全进) Acta Physica Sinica (Overseas Edition), 1999, 8 (1):  21-26.  DOI: 10.1088/1004-423X/8/1/004 Abstract ( 1794 )   PDF (249KB) ( 412 )   The B$\rho$-$\Delta$E-B$\rho$-TOF techniques used for the identification and separation of radioactive nuclear beams (RNB) at RIBLL, are described. As a PF-type radioactive nuclear beam line, RIBLL can deliver RNB with high purity for light projectiles by using B$\rho$-$\Delta$E-B$\rho$ techniques, while for heavy ones, the B$\rho$-$\Delta$E-B$\rho$-TOF methods must be adopted in order to identify the RNB clearly.

CLASSICAL AREAS OF PHENOMENOLOGY

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ACOUSTIC INVERSE METHOD FOR MEASURING THE SIZE-DISTRIBUTION OF THE DROPS AND THE MOISTURE CONTENT IN WATER (CLOUD) FOG Qian Zu-wen (钱祖文), Shao Dao-yuan (邵道远), Li Xian-hui (李贤徽), Wang De-zhao (汪德昭) Acta Physica Sinica (Overseas Edition), 1999, 8 (1):  27-31.  DOI: 10.1088/1004-423X/8/1/005 Abstract ( 1344 )   PDF (191KB) ( 423 )   The acoustic-energy loss was measured when the sound wave propagated through a layer of water fog. By the application of the sound attenuation theory in granular media and by means of the acoustic inverse (optimization) method, the size-distribution of the drops and the moisture content in the water fog were measured. It is demonstrated that the sizes of the water drops obey the normal distribution approximately. Comparison of the size-distribution results between data obtained by the inverse measurements and those obtained by the optic-microscopic-size methods shows good agreement with each other. The results of the moisture content and the thickness of the fog layers obtained by this method are also consistent with the results measured by other methods (for example, the water-content weight and the direct measurement of layer's thickness by a scale, etc.) reasonably.

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

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ION HEATING EFFECTS IN LHCD SUSTAINED LOW DENSITY TOKAMAK PLASMAS Kuang Guang-li (匡光力) Acta Physica Sinica (Overseas Edition), 1999, 8 (1):  32-39.  DOI: 10.1088/1004-423X/8/1/006 Abstract ( 1212 )   PDF (214KB) ( 554 )   In low density (～1018 cm-3) plasmas sustained by lower hybrid current drive in the high magnetic field superconducting tokamak Triam-1M (Kyushu University, Japan), high ion temperature has been frequently observed by an NEA diagnostic. The experimental phenomena are briefly described and analyzed in the paper. It is suggested by the analysis that the high ion temperature of the low density tokamak plasmas is attributed to ion Landau damping of lower hybrid wave.

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

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ORGANOMETALLIC SYNTHESIS AND QUANTUM SIZE EFFECT OF CdSe NANOCRYSTALLITES Huang Hong-bin (黄宏彬), Xu Ling (徐岭), Chen Hong-ming (陈红明), Huang Xin-fan (黄信凡), Chen Kun-ji (陈坤基), Feng Duan (冯端) Acta Physica Sinica (Overseas Edition), 1999, 8 (1):  40-45.  DOI: 10.1088/1004-423X/8/1/007 Abstract ( 1456 )   PDF (224KB) ( 442 )   We have prepared nearly monodisperse CdSe nanocrystallites with diameters of 1-4 nm from the rapid pyrolysis of organometallic precursors in a hot coordinating solvent. The nanocrystal structures have been characterized by transmission electron microscopy and electron diffraction. From the absorption spectrum, we have observed the prominent peak of 1S-1S excitonic transition, which is obviously blue-shifted from the bulk bandgap and the largest shift is about 1.25 eV. We have used a theoretical model based on the tight binding approximation to analyze the quantum size effect of these nanocrystallites. The results have been compared with those of the effective mass approximation model.

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CALCULATION OF ELECTRONIC STATES OF Si(337) SURFACE Jia Yu (贾瑜), Ma Bing-xian (马丙现), Shen San-guo (申三国), Yang Shi-e (杨仕娥) Acta Physica Sinica (Overseas Edition), 1999, 8 (1):  46-51.  DOI: 10.1088/1004-423X/8/1/008 Abstract ( 1326 )   PDF (196KB) ( 466 )   Using the scattering-theoretic method and employing the nearest-neighbor tight-binding formalism to describe the bulk electronic structure, we have studied the electronic structure of Si(337) surface. The wave-vector-resolved layer densities of states are presented. The results show that there are six surface bound states in the range from -12.0 to 2.0 eV. Some properties of these surface states are discussed.

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PARABOLIC APPROXIMATION OF THE SPECIFIC HEAT IN QUANTUM XY SPIN GLASS MODEL WITH PLANAR DZYALOSHINSKII-MORIYA INTERACTIONS IN LONGITUDINAL FIELD Shang Yu-min (商育民), Yao Kai-lun (姚凯伦) Acta Physica Sinica (Overseas Edition), 1999, 8 (1):  52-56.  DOI: 10.1088/1004-423X/8/1/009 Abstract ( 1188 )   PDF (199KB) ( 550 )   The quantum infinite range XY spin glass model with the infinite range planar Dzyaloshinskii-Moriya interaction in external field for spin S=1/2 is investigated theoretically. Numerical calculations show that, the specific heat depending on the temperature has crossover behavior; the weak field dependence of the specific heat can be fitted by the parabolic approximation, C/T=A+Bh2, the coefficient B is peaked near the transition point.

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X-RAY PHOTOELECTRON SPECTROSCOPY STUDY ON ELECTROCHROMIC V2O5 THIN FILM Wang Zhong-chun (王忠春), Li Zhi-yong (李智勇), Chen Xiao-feng (陈晓峰), Hu Xing-fang (胡行方) Acta Physica Sinica (Overseas Edition), 1999, 8 (1):  57-62.  DOI: 10.1088/1004-423X/8/1/010 Abstract ( 1115 )   PDF (195KB) ( 1111 )   Nanocrystalline V2O5 thin films were reactively radio-frequency magnetron-sputtered under optimal deposition parameters. Their electrochemical and electrochromic characteristics were investigated by cyclic voltammetry and in-situ monochromatic transmittance measurements. Upon lithium intercalation, V2O5 thin films showed a double electrochromic behavior depending on the wavelength and the intercalation extent. X-ray photoelectron spectroscopy results showed that part of the V5+ in V2O5 was reduced to V4+ during the Li+ intercalation process.

GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS

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PULSED EMISSION OF VERY HIGH ENERGY GAMMA RAYS FROM CRAB PULSAR Xu Chun-xian (徐春娴), He Hui-lin (何会林), He Hui-hai (何会海), Chen Yong-zhong (陈永中), Li Hui-dong (李辉东), Jiang Yin-lin (姜印琳) Acta Physica Sinica (Overseas Edition), 1999, 8 (1):  63-70.  DOI: 10.1088/1004-423X/8/1/011 Abstract ( 1161 )   PDF (237KB) ( 534 )   We present here the results of observation of very high energy(VHE) gamma-ray emission from Crab Pulsar with the Beijing Atmospheric Cerenkov Telescopes, named ACT2 and ACT3, during the 1995－1996 season. The data are based on 168 h (ACT2) and 125 h (ACT3) of exposure over the period of observation in tracking mode. After converting the event time to the solar barycentre, the data have been searched for evidence of pulsed emission at 33 ms period of Crab Pulsar. We found no steady emission of VHE Gamma-ray with 33 ms period at the time scale of month or nights. But there are two evidences of sporadic emission over an hour duration with the same period as the one at radio wave band.