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1998年, 第7卷, 第5期　刊出日期：1998-05-20 上一期    下一期

NUCLEAR PHYSICS

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PSEUDORAPIDITY DISTRIBUTIONS OF RELATIVISTIC SINGLY CHARGED PARTICLES IN HIGH ENERGY NUCLEUS-NUCLEUS COLLISIONS 刘福虎 1998 (5):  321-326.  doi: 10.1088/1004-423X/7/5/001 摘要 ( 1203 )   PDF(193KB) ( 334 )   The pseudorapidity distributions of relativistic singly charged part icles produced in high energy nucleus-nucleus collisions are described by the thermalized cylinder picture. The calculated results are in agreement with the recent experimental data of gold induced interactions at the Brookhaven National Laboratory. 相关文章 | 计量指标

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CALCULATIONS OF STRETCHING VIBRATIONAL OVERTONES AND COMBINATIONS OF ARSINE BY NONLINEAR MODEL 陈向荣, 芶清泉, 庞小峰 1998 (5):  327-332.  doi: 10.1088/1004-423X/7/5/002 摘要 ( 1228 )   PDF(158KB) ( 370 )   A three-parameter nonlinear model in nonlinear quantum theory,i.e.,the quantized discrete self trapping equation, has been used to calculate the vibrational energy spectrum, including the overtones and combinations with many excited quanta, of AsH stretches of arsine, AsH3. The model calculations agree well with experiment and other calculations. It is shown that the dominant feature of the energy spectrum of AsH3 molecule is a pattern of local mode pairs, and that when n≥4, all the vibrational energies are almost localized on a single AsH bond. 相关文章 | 计量指标

ATOMIC AND MOLECULAR PHYSICS

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ANALYSIS OF F′0+u ION-PAIR STATE OF IODINE 张连水, 刘宁宁, 李晓苇, 傅广生 1998 (5):  333-339.  doi: 10.1088/1004-423X/7/5/003 摘要 ( 1250 )   PDF(171KB) ( 359 )   The optical-optical double resonant multiphoton ionization (OODR-MPI) technique and the fluorescent excitation spectroscopy technique have been applied to the study of the F′0+u ion-pair state of iodine. This paper presents OODR-MPI spectrum and fluorescent excitation spectrum of I2 in the region of 54000-55300cm-1 by the three-photon resonant, two-photon ionization (1+2+2) and (1+(1+1)+2) processes. 相关文章 | 计量指标

CLASSICAL AREAS OF PHENOMENOLOGY

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HOW DOES AN IMPERFECT SYSTEM AFFECT THE MEASUREMENT OF SQUEEZING? 张天才, 张俊香, 谢常德, 彭堃墀 1998 (5):  340-347.  doi: 10.1088/1004-423X/7/5/004 摘要 ( 1071 )   PDF(186KB) ( 366 )   The effect of an imperfect system on the measurement of squeezing is studied. It is shown that the imperfectly efficient detectors and the unbalance of the beam-splitter will reduce the measured squeezing. The effects on quadrat ure phase squeezing and photon number squeezing are different from the usual balanced homodyne detection. 相关文章 | 计量指标

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THEORETICAL STUDY OF THE GROUND-STATE PROPERTY OF THE TWO-DIMENSIONAL HEISENBERG ANTIFERROMAGNET ON A TRIANGULAR LATTICE 董占海, 冯世平 1998 (5):  348-353.  doi: 10.1088/1004-423X/7/5/005 摘要 ( 1531 )   PDF(171KB) ( 366 )   Within the Tyablikov's theoretical framework, the ground-state property of the two-dimensional antiferromagnetic Heisenberg model on a triangular lattice is studied. Our results show that the sublattice magnetization is M=0.241 and the ground-state energy per bond is Eg/ NZJ =-0.166, which are in agreement with the numerical simulations. 相关文章 | 计量指标

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MAGNETIC PROPERTIES OF Pr2Co17-x Mx ( M＝Ga,Si) COMPOUNDS 张绍英, 沈保根, 李润伟, 梁兵, 张宏伟, 成昭华, 王芳卫, 詹文山, 张立刚 1998 (5):  354-360.  doi: 10.1088/1004-423X/7/5/006 摘要 ( 1236 )   PDF(200KB) ( 365 )   The influence of Ga or Si substitution for Co on the structural and magnetic properties of Pr2Co17 compounds is investigated. All samples studied here are single phase and have the rhombohedral Th2Zn17-type structure. The unit-cell volume is found to increase linearly by the substitution of Ga for Co,but reduce by the substitution of Si for Co in Pr2Co17 compounds. In Pr2Co17-x Mx, the Curie temperature decreases monoto nically with increasing at an approximate rate of 153K per Ga atom and 175K per Si atom. The saturation magnetic moment of Pr2Co17-x Mx ( M=Ga,Si) decreases with increasing x. The rates of the decrease are larger than that expected as a simple dilution. For Pr2Co17-xSix ,the spin reorientation transition is observed above room temperature. The spin-reorientation temperature Tsrfirst decreases with increasing Si content and then increases at higher x values (x>2). The spin reorientat ion behavior is interpreted by the competition between the Pr and Co sublattice anisotropies. The easy magnetization direction in Pr2Co17-xGax compounds is perpendicular to the c-axis, and no spin reorientation transition is observed. 相关文章 | 计量指标

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SPIN-DEPENDENT INTERFACIAL TUNNELING AND MAGNETO RESISTANCE IN THE FAMILY OF GRANULAR PEROVSKITE La1-xSrxMnO*3 张宁, 丁维平, 谭锡林, 徐寅林, 邢定钰, 都有为 1998 (5):  361-367.  doi: 10.1088/1004-423X/7/5/007 摘要 ( 1344 )   PDF(225KB) ( 374 )   The magnetic transport properties in granular perovskite system La1-xSrxMnO*3 have been investigated. The spin-dependent inter facial tunneling and the corresponding giant magnetoresistance (GMR) effect have been observed in the whole temperature range below the Curie point Tc for the samp les with concentration x from 0.05 to 0.45. Theoretical analysis shows that the interfacial tunneling originates from the difference in magnetism between surfaces and cores, and the tunnel-type GMR stems from the field-induced change of interfacial magnetic order. 相关文章 | 计量指标

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LINEAR AND NONLINEAR INTERSUBBAND OPTICAL PROPERTIES IN A STEP QUANTUM WELL WITH AN APPLIED ELECTRIC FIELD 常凯, 吴文刚, 江德生, 夏建白 1998 (5):  368-378.  doi: 10.1088/1004-423X/7/5/008 摘要 ( 1456 )   PDF(251KB) ( 356 )   Within the framework of the effective-mass envelope-function theory , the field-dependent intersubband optical properties of a Al0.4Ga0.6As/Al0.2Ga0.8As/GaAs step quantum well are investigated theoretic ally based on the periodic boundary condition. A very large Stark shift occurs when the lowest subband electron remains confined to the small well while the hig her subband electron confined to the big well. The optical nonlinearity in a step well due to resonant intersubband transition(ISBT) is analyzed using a density matrix approach. The second-harmonic generation coefficient χ(2)2ω and nonlinear optical rectification χ(2)0 have also been investigated theoretically. The results show that the ISBT in a step well can generate very large second order optical nonlinearities,χ(2)0 and χ(2)2ω can be tuned by the electric field over a wide range. 相关文章 | 计量指标

8000 CROSSDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

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A KINETIC MODEL FOR THE INITIAL GROWTH OF DIAMOND FILMS 刘秋香, 王金斌, 杨国伟, 游建强 1998 (5):  379-387.  doi: 10.1088/1004-423X/7/5/009 摘要 ( 781 )   PDF(279KB) ( 314 )   Based on a surface reaction mechanism for diamond deposition from the gas phase, a kinetic model is developed to describe diamond nucleation sites and the initial stage of diamond growth in chemical vapor deposition. The timein dependent solutions to the rate equations, which describe the steady-state growth of diamond films, is obtained analytically for the case of small ratio of car bon flux to atomic hydrogen flux. The time-dependent solutions obtained by nume rical methods for large ratio of carbon to atomic hydrogen flux describe the nucleation and initial gorwth stage of diamond films. This model suggests some general predictions for diamond nucleation and growth and can be used to explain several important experimental phenomena observed by others. 相关文章 | 计量指标