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1995年, 第4卷, 第2期　刊出日期：1995-02-20 上一期    下一期

GENERAL

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SHAPE EQUATION AND SHAPES OF AXISYMMETRIC VESICLES IN TOROIDAL TOPOLOGY 胡建国, 欧阳钟灿 1995 (2):  81-87.  doi: 10.1088/1004-423X/4/2/001 摘要 ( 1392 )   PDF(215KB) ( 366 )   For toroidal topology we solve the shape equation for axisymmetric vesicles numerically. The phase diagram is found to be similar to that from another shape equation. This similarity is the result of the insensitive dependence of beading energy upon detailed shape of vesicles and the constant volume and area ensemble we are considering. We argue that the very small distance between two opposite cusps of the sickle-shaped vesicle makes it unstable and fuse into two encompassed spheres which might be observed in experiment. The spontaneous curvatures of the observed Clifford tori are also estimated. 相关文章 | 计量指标

THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

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CHIRAL ANOMALY AND UNAMBIGUOUS TERMS OF EXACT SCALE BEHAVIOR 杨继锋, 倪光炯 1995 (2):  88-98.  doi: 10.1088/1004-423X/4/2/002 摘要 ( 1136 )   PDF(271KB) ( 349 )   We perform new explicit and regularization-independent calculations of < AV > amplitude in QED1+1 and amplitude in QED1+3 respectively to reinvestigate the anomaly problem. A kind of finite and unambiguous terms of exact scale behavior (in momentum space) is found to be responsible for the anomalies both in QED1+1 and QED1+1. They come from logarithmically divergent momentum integrals in contrast with the usual knowledge for triaugle anomaly in QED1+3. In QED1+1, this term is also responsible for photon mass generation. Some implications and possible relations with other aspects of anomaly are discussed. 相关文章 | 计量指标

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CALCULATION ON A CLUSTER MODEL FOR THE ELECTRONIC CHARGE DENSITY AT NUCLEAR SITE AND THE ELECTRONIC STRUCTURE PARAMETERS OF α IRON 白魁昌, 尹国成, 江自应 1995 (2):  99-104.  doi: 10.1088/1004-423X/4/2/003 摘要 ( 1168 )   PDF(187KB) ( 328 )   In order to investigate the M$\ddot{o}$ssbauer isomer shifts and its related electronic charge densities for some substances, the electronic charge density at nuclear site of a iron have been computed for an octahedral cluster Fe6 with SCF MS-Xα method. Some other electronic structure parameters of the cluster have also been obtained, such as the orbital energy distri- bution, the electron density of states, the Fermi level and various kinds of electron energies, etc. The cohesive energy of α iron have also been calculated and discussed. 相关文章 | 计量指标

ATOMIC AND MOLECULAR PHYSICS

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THE EFFECT OF PULSE SHAPE AND STEPOUT IN THE THREE-STEP PHOTOIONIZATION 谢世亮, 王德武, 应纯同 1995 (2):  105-112.  doi: 10.1088/1004-423X/4/2/004 摘要 ( 1474 )   PDF(205KB) ( 362 )   The laser pulse shape effect and mainly the stepout effect on the ionization are investigated numerically in this paper. About the pulse shape effect, the result shows that it would be better to use shorter Gaussian pulses on the condition of constant area. About the stepout problem, the calculation shows that a certain stepout between pulses will benefit the ionization. Some interesting phenomena caused by stepout among pulses are found and explained in population dynamics. 相关文章 | 计量指标

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ISOTHERMAL CRYSTALLIZATION KINETICS OF BALL-MILLED AMORPHOUS Al-Ni-Zr ALLOY 高文莉, 都有为, 王开阳, 全明秀, 王景唐 1995 (2):  113-117.  doi: 10.1088/1004-423X/4/2/005 摘要 ( 1247 )   PDF(124KB) ( 375 )   The isothermal crystallization kinetics of amorphous Al-Ni-Zr alloy produced by mechanical alloying was studied by means of differential scanning calorimetry. Accordiag to Arrhenius equation, the apparent activation energy was calculated. The isothermal crystal-lization kinetics follows Johnson-Mehl-Avrami equation with n=2.00 within 0.15 相关文章 | 计量指标

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ION-BEAM-INDUCED SOLID PHASE CRYSTALLIZATION OF MeV Si+-IMPLANTED Si(100) 徐天冰, 朱沛然, 周俊思, 李岱青, 任廷琦, 赵清太, 刘向东, 刘洁田 1995 (2):  118-124.  doi: 10.1088/1004-423X/4/2/006 摘要 ( 1257 )   PDF(196KB) ( 365 )   The behavior of ion-beam-induced crystallization of a buried amorphous layer created by means of MeV Si+ irradiation at 300℃ in Si(100) was studied by Rutherford backscattering and channeling technique. Sohd phase epitaxial crystallizations occurred from both the front and the back amorphous-crystalline(a/c) interfaces with the growth thickness being increased linearly with increasing dose of the annealing ion beam, Nuclear energy deposition was proved to play a dominant role in the process of ion-beam-induced crystallization. The high density of electronic excitation, which could enhance defect production near or at the a/c interface, may thus enhance the nuclearly normalized growth rate of ion-beam-induced crystallization at the front a/c interface. 相关文章 | 计量指标

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JAHN-TELLER EFFECT AND SUPERCONDUCTING MECHANISM OF THE HOLE-DOPED C60 SOLID 陈锋, 徐铁峰, 严大东, 李文铸 1995 (2):  125-129.  doi: 10.1088/1004-423X/4/2/007 摘要 ( 1307 )   PDF(147KB) ( 407 )   A possible superconducting mechanism of the hole-doped C60 solid is discussed. Under the assumption that the superconductivity results from the strong coupling between electrons at Fermi surface and intramolecular vibrations, a simple expression for the electron-phonon coupling parameter λ is derived. The related transition temperature is estimated and can be much greater than that of the alkali-metal-doped C60 solid. 相关文章 | 计量指标

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STUDIES OF THE MULTILAYER MIRROR REFLECTIVITY IN SOFT X-RAY REGION 缪建伟, 崔明启, 王俊, 唐鄂生 1995 (2):  130-138.  doi: 10.1088/1004-423X/4/2/008 摘要 ( 1359 )   PDF(240KB) ( 382 )   Four factors (the interface roughness, the monotonous thickness drift, the interdiffusion between two layers and the change of extinction coefficients) which may affect the multilayer mirror reflectivity in soft X-ray region are investigated. Some conclusions are obtained by our theoretical analysis. In long wavelength region (λ> 12nm), the change of extinction coefficients is the main cause reducing the multilayer mirror reflectivity and others (excluding the interface roughness) only shift the peak position. In short wavelength region (λ<10nm), all the four factors affect the reflectivity. In addition, the two factors, monotonous thickness drift and interdiffusion between two layers, shift the peak position. To check these conclusions, the measurement of a Nb/Si multilayer mirror fabricated by our magnet sputtering system is performed on an X-ray generator and a reflectometer installed on the Beijing Synchrotron Radiation Facility. The experimental results are in good agreement with our calculations, and the reflectivity up to 32 % of the Nb/Si multilayer mirror (with 41 layers and at wavelength 17.59nm) is attained. 相关文章 | 计量指标

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INVESTIGATION OF DEFECTS IN Ge-DOPED GaAs CRYSTAL GROWN IN A MAGNETIC FIELD 康俊勇, 黄启圣 1995 (2):  139-146.  doi: 10.1088/1004-423X/4/2/009 摘要 ( 924 )   PDF(290KB) ( 318 )   Ge-doped GaAs single crystals have been grown by liquid-encapsulated Czochralski method in absence and presence of a magnetic field of 4000Gauss. By means of high op-tical efficiency photoluminescence, spectra of the grown crystals at room temperature were obtained, which consist of two emission bands A and B at 1.39-1.42eV and 0.97-1.05eV, respectively. Comparing the photoluminescence mappings with microphotographs of etched wafers, Hall effect results and electron probe microanalyses of the n- and p-type crystals with different Ge concentrations, we considered that the emission bands A and B originate from Ge-related acceptor and donor complexes, respectively. The complexes were formed during crystal growth, mainly due to temperature fluctuations in molten Ge-doped GaAs. The concentrations and homogeneities of the defects can be improved by the application of a magnetic field during crystal growth to suppress the temperature fluctuation. 相关文章 | 计量指标

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THE DEPENDENCE OF HAWKING THERMAL SPECTRUM ON ANGULAR VARIABLES 杨树政, 朱建阳, 赵峥 1995 (2):  147-150.  doi: 10.1088/1004-423X/4/2/010 摘要 ( 1113 )   PDF(79KB) ( 352 )   The thermal radiation spectrum of a generally non-stationary black hole is studied. The conclusion is discussed in some special cases. The calculation and the discussion show that the thermal radiation spectrum may depend on the angular variables of the black hole. 相关文章 | 计量指标