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1994年, 第3卷, 第10期　刊出日期：1994-10-20 上一期    下一期

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TWO-PARTICLE BOUND STATES IN THE QUANTUM SINE-GORDON FIELD THEORY IN (D+1) DIMENSIONS 卢文发, 许伯威, 章豫梅 1994 (10):  721-729.  doi: 10.1088/1004-423X/3/10/001 摘要 ( 1280 )   PDF(225KB) ( 444 )   The two-particle states of the quantum sine-Gordon fields are studied variationally in (D+1) dimensions using the Gaussian wave functional approach. In both (1+1) and (2+1) dimensions, there exist two-particle bound states for certain ranges of coupling constant, where the vacuum states are stable. In the higher dimensions (D > 2), this approximation indicates that the two-particle states may be only the states consisting of two free particles, which is conformable to the triviality of the sine-Gordon field theory previously obtained in recent literatures. 相关文章 | 计量指标

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NMR STUDIES OF HYDROGEN MICROSTURUCTURES IN HYDROGENATED AMORPHOUS SILICON FILMS 瞿学选, 陈坤基, 陈茂瑞, 胡澄, 李志锋, 冯端 1994 (10):  730-735.  doi: 10.1088/1004-423X/3/10/002 摘要 ( 1426 )   PDF(167KB) ( 394 )   Four kinds of a-Si: H films deposited in the PECVD system with different Ts are studied by 1H NMR technique. Direct evidence is given to confirm hydrogen atoms in the diluted and clustered phases. The local bonding configurations for hydrogen and the density of dangling bonds are analyzed by ESR and infrared absorption spectroscopy. The behaviour of hydrogen in a-Si; H films is discussed. 相关文章 | 计量指标

CLASSICAL AREAS OF PHENOMENOLOGY

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THEORETICAL STUDY ON THE DIRECT RECONSTRUCTION OF LLFT X-RAY HOLOGRAM WITH VISIBLE LIGHT 肖体乔, 陈建文, 徐至展, 朱佩平, 寇雷刚, 王之江 1994 (10):  736-745.  doi: 10.1088/1004-423X/3/10/003 摘要 ( 1293 )   PDF(284KB) ( 459 )   Reconstructing X-ray hologram with visible light, without enlargement of it, can sim-plify the process of its reconstrution greatly. For lensless Fourier transform (LLFT) X-ray holography, there is no spherical aberration in it and the spacing of its interference fringes is relatively large. Therefore, it is possible to reconstruct hologram of this type directly with visible light. The effects of aberrations and emulsion shrinkage on the resolution of LLFT X-ray hologram, the conditions for perfect reconstructing of the recorded information are analyzed, and the results of corresponding numerical analyses are also given. As a result, the legibility for direct reconstructing of LLFT X-ray hologram with visible light is verified theoretically, In addition, the longitudinal resolution in X-ray holography is analyzed, and the conditione for longitudinal resolving in X-ray holography are given from the relationship between longitudinal and transverse resolution. 相关文章 | 计量指标

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BEHAVIOR OF Ar PLASMA FORMED IN A HIGH DENSITY PLASMA SOURCE-AN ECR REACTOR 吴汉明, D.B. GRAVES, R.K PORTEOUS, 李明 1994 (10):  746-757.  doi: 10.1088/1004-423X/3/10/004 摘要 ( 1240 )   PDF(349KB) ( 464 )   In order to develop the ultra-large scale integration(ULSI), low pressure and high density plasma apparatus are required for etching and deposit of thin films. To understand critical parameters such as the pressure, temperature, electrostatic potential and energy distribution of ions impacting on the wafer, it is necessary to understand how these parameters are influenced by the power input and neutral gas pressure. In the present work, a 2-D hybrid electron fluid-particle ion model has been developed to simulate one of the high density plasma sources-an Electron Cyclotron Resonance (ECR) plasma system with various pressures and power inputs in a non-uniform magnetic field. By means of numerical simulation, the energy distributions of argon ion impacting on the wafer are obtained and the plasma density, electron temperature and plasma electrostatic potential are plotted in 3-D. It is concluded that the plasma density depends mainly on both the power input and neutral gas pressure. However, the plasma potential and electron temperature can hardly be affected by the power input, they seem to be primarily dependent on the neutral gas pressure. The comparison shows that the simulation results are qualitatively in good agreement with the experiment measurements. 相关文章 | 计量指标

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

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THE ION CURRENT BEHAVIOR IN ECR ARGON PLASMA 姚鑫兹, 江德仪, 任育峰 1994 (10):  758-763.  doi: 10.1088/1004-423X/3/10/005 摘要 ( 1116 )   PDF(184KB) ( 372 )   The ion current density as a function of various system parameters, such as pressure, magnetic field, and microwave power, has been studied by using Faraday cup. The bistability of plasma was observed and discussed. 相关文章 | 计量指标

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A NEUTRON POWDER DIFFRACTION STUDY OF THE STRUCTURE IN Nd2Fe17Nx(x = 2.5, 3.0, 5.5) 严启伟, 张泮霖, 孙向东, 魏玉年, 孙克, 胡伯平, 王亦忠, 刘贵川, 勾成, 程玉芬, 陈东风 1994 (10):  764-768.  doi: 10.1088/1004-423X/3/10/006 摘要 ( 1261 )   PDF(118KB) ( 367 )   The crystallographic and magnetic structures of Nd2Fe17Nx(x = 2.5, 3.0, 5.5) at room temperature were refined by Rietveld analysis of neutron powder diffraction data. We found that Nd2Fe17Nx has a Th2Zn17 type structure (S.G. R3m) and the nitrogen atoms occupy both 9e and 18g sites simultaneously and at different rates. 相关文章 | 计量指标

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QUANTUM PERCOLATION AND BALLISTIC CONDUCTANCE IN A SYSTEM OF DOUBLE-COUPLED CHAINS 范旭东, 顾本源, 杨国桢, 林宗涵 1994 (10):  769-779.  doi: 10.1088/1004-423X/3/10/007 摘要 ( 1237 )   PDF(321KB) ( 400 )   The quantum-mechanical calculation of electronic conductance in double-coupled chains as a function of the interchain bonding probability p is presented. The calculated results show that one still can see the basic plateaus in the ensemble-averaged conductance curves as a function of the Fermi energy for the weak disorder. In addition, dense irregularly oscillating structures are superimposed upon each plateau. The characteristics of the conductance are very sensitive to the presence of the interchain broken bonds. For the strong disorder (p≈0.5) the conductance quantization breaks down. The accuracy of the quantization conductance rapidly drops down as the value of p approaches 0.5. The ensemble-averaged value of the logarithmic conductance as a function of the sample length exhibits a linear variation, determining a localization length. Both the localization length and the root-mean- square (RMS) value of the conductance fluctuations depend on p and the Fermi energy of electrons. The variations of the localization length and RMS with p are both of an approximate parabolic function around p≈0.5. No percolation transition is found for this quasi-one-dimensional system, as expected. 相关文章 | 计量指标

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TEMPERATURE DEPENDENCE OF ANISOTROPY IN Co/X(Pt, Au, Ag, Ni) MULTILAYER FILMS 张慧云, 王荫君 1994 (10):  780-787.  doi: 10.1088/1004-423X/3/10/008 摘要 ( 1464 )   PDF(260KB) ( 396 )   Temperature dependences of effective perpendicular anisotropy (PA) Ku and inter-face energy Ks for Co/X(Pt, Au, Ag, Ni) multilayer films(MFs) as well as of spontaneous magnetization Ms for Co/Pt and Co/Au MFs are reported. The dependence of Ks on T dis-tinguishes between Go/Au, Co/Ni and Co/Pt, Co/Ag MFs, i.e., Ks of the former decreases with the increase of T, but it increases for the latter. Co/Pt MFs with the perpendicular anisotropy possess a large enhancement of Ms at low temperature, but there is not any en-hancement for Co/Au MFs. We have discussed the source of PA in Co/Au and Co/Pt MFs and speculated that the strain due to the lattice mismatch may be the main cause of PA in Co/Au MFs, but it is not for Co/Pt MFs. 相关文章 | 计量指标

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

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A MODIFIED METHOD OF DETERMINING FRACTAL DIMENSIONS OF POLYMERS AND BIOPOLYMERS 肖奕, 姚凯伦 1994 (10):  788-792.  doi: 10.1088/1004-423X/3/10/009 摘要 ( 818 )   PDF(136KB) ( 313 )   A modified method of calculating the end-to-end distance of segments with a given number of units in a single polymer chain is presented and numerical studies of some fractals by using Havlin and Ben-Avraham's and our methods are given. The results show that our method can remove the fluctuations in the end-to-end distances of the segments arising in Havlin and Ben-Avraham's method. 相关文章 | 计量指标