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1998年, 第7卷, 第3期　刊出日期：1998-03-20 上一期    下一期

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AL L CORE EDGE FINE STRUCTURE IN Al, AlN AND α-Al2O3：A COMPARISON OF MICROELECTRON ENERGY LOSS SPECTRA WITH THEORY 樊锡君, J.S.BOW, R.W.CARPENTER, S.H.LIN, 田淑芬 1998 (3):  214-226.  doi: 10.1088/1004-423X/7/3/009 摘要 ( 1088 )   PDF(400KB) ( 317 )   The Al L near-edge fine structures of aluminum and its compounds with nitrogen and oxygen are studied using electron energy loss microspectroscopy in a transmission electron microscope. These edges are normalized to the same scattering cross section per Al atom per electronvolt. The cross section is calculated by using the Born approximation. The contributions to the cross section are from the valence shell crystal states obtained by using the extended Hückel band calculation and the ionization states obtained by using the electron gas model. The chemical effects in the ionization region are taken into account by in cluding the contributions from the elastic backscattering of outgoing plane waves by the atoms that neighbor the excited atoms. The results by theoretical calculation agree semiquantitatively with experimental results. 相关文章 | 计量指标

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CORE POLARIZATION CORRECTIONS FOR THE PHOTOIONIZATION OF SODIUM 程延松, 刘锦超, 孙卫国 1998 (3):  161-166.  doi: 10.1088/1004-423X/7/3/001 摘要 ( 1333 )   PDF(144KB) ( 356 )   Many-body perturbation theory with an effective operator is applied to the calculations of photoionization of sodium by consistently including the static and dynamic core polarization. The cross section for the transition (2p→kd+ ks) is obtained by taking into account the dipole and quadrupole core polarization. The results are compared with the many-body perturbation results and measurements. 相关文章 | 计量指标

ATOMIC AND MOLECULAR PHYSICS

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DYNAMIC SCREENING OF THE THREE-BODY COULOMB INTERACTIONS 陈长进 1998 (3):  167-173.  doi: 10.1088/1004-423X/7/3/002 摘要 ( 1172 )   PDF(187KB) ( 336 )   The BBK approach is modified by the introduction of effective Sommerf eld parameters for both symmetric and asymmetric geometries, according to the fact that the strength of any particular two body Coulomb interaction is affected by the presence of the third particle. The triple differential cross sections for electron impact ionization of atomic helium at incident energies of 40 and 50 eV in asymmetric geometry are calculated. Results of this approach are found to be in good agreement with the absolute measurements and the only existing theoretical results of the convergent close-coupling method. 相关文章 | 计量指标

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PREPARATION OF NONCLASSICAL STATES OF A CAVITY FIELD BASED ON A NONLINEAR JAYNES-CUMMINGS MODEL 魏渭, 郭光灿 1998 (3):  174-182.  doi: 10.1088/1004-423X/7/3/003 摘要 ( 1155 )   PDF(213KB) ( 350 )   It is proven in this paper that some kinds of nonclassical quantum states of the cavity field, such as Schr?dinger cat state (amplitude cat or phase cat), sub-Poissonian photon distribution and Fock state, etc., can be generated by conditional meas urements on atoms in the two-photon Jaynes-Cummings model with a Kerr-like medium. The nonlinear constant plays the key modulation role in the preparation of the quantum states, which gives a new controllable parameter for further experi mental researches in this field. 相关文章 | 计量指标

CLASSICAL AREAS OF PHENOMENOLOGY

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COHERENT STATES FOR ONE-DIMENSIONAL INFINITELY DEEP SQUARE POTENTIAL WELL 倪致祥 1998 (3):  183-189.  doi: 10.1088/1004-423X/7/3/004 摘要 ( 1264 )   PDF(163KB) ( 360 )   The energy spectrum-generating algebra for one-dimensional infinitely deep square potential well is constructed by using an additional phase variable, and a class of sets of the annihilation operator coherent states are introduced. These sets are strongly continuous in their parameter on the whole complex plane and satisfy the overcompleteness relation in a curved parameter space with rotational symmetry. 相关文章 | 计量指标

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PHOTO ACOUSTIC MEASUREMENTS OF WATER VAPOR ABSORPTION COEFFICIENT IN UV SPECTRAL REGION B.A.TIKHOMIROV, V.O.TROI TSKII, V.A.KAPITANOV, G.S.EVTUSHENKO, Y.N.PONOMAREV 1998 (3):  190-195.  doi: 10.1088/1004-423X/7/3/005 摘要 ( 1135 )   PDF(165KB) ( 433 )   Data on the absorption coefficient of H2O in binary mixture with N2 in UV region of spectra are presented. With the use of the high sensitivity photoacoustic spectrometer, the following values of the absorption coefficient were found: 2.3×10-9cm-1·Pa-1(λ=255 nm), 0.9×10-9 cm-1·Pa-1(λ=271 nm), and 1.6×10-9cm-1 ·Pa-1(λ=289 nm). 相关文章 | 计量指标

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QUANTUM DIFFUSION IN TWO-DIMENSIONAL OCTAGONAL QUASICRYSTALS 袁辉球, 钟建新 1998 (3):  196-202.  doi: 10.1088/1004-423X/7/3/006 摘要 ( 1276 )   PDF(208KB) ( 387 )   We have studied the quantum diffusion in an octagonal quasiperiodic tiling. Paticular attention is paid to the analysis of long-time behavior of the autocorrelation function C(t) and the relationship between diffusion and fractal dimensions of energy spectrum. For the pure hopping model, numerical calculations show that C(t)～t-1 , which corresponds to the case of periodic systems. For the combined model, in which the contribution of site potentials is considered, C(t)～t-δ with 0＜δ≤1. The scaling factor δ is related to Hamiltonian parameters and the type of site where electron is initially located. Moreover, we find a crossover from δ=1 to 0＜δ＜1 with increasing site potentials. 相关文章 | 计量指标

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OPTICAL PROPERTIES OF ZnO COMPOSITE NANOPARTICLES 王荣瑶, 吴晓春, 武鹏飞, 邹炳锁, 汪力, 许景周, 徐积仁, 王新峰, 王振家, 陈建新 1998 (3):  203-208.  doi: 10.1088/1004-423X/7/3/007 摘要 ( 1607 )   PDF(177KB) ( 408 )   We have synthesized core/shell structure ZnO composite nanoparticles by surface chemical modification. This new composite material shows a large optical gap redshift compared with the homogeneous ZnO nanoparticles. The visible photoluminescence ranging from blue to red in color with fast decay time may be as signed to the interfacial bound-exciton-like emission. 相关文章 | 计量指标

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

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STUDY OF MICROSTRUCTURE AND ELECTROLUMINESCENCE OF ZINC SULFIDE THIN FILM 柳兆洪, 王余姜, 陈谋智, 陈振湘, 孙书农, 黄美纯 1998 (3):  209-213.  doi: 10.1088/1004-423X/7/3/008 摘要 ( 1187 )   PDF(167KB) ( 464 )   The electroluminscent zinc sulfide thin film doped with erbium, fabri cated by thermal evaporation with two boats, are examined. The surface and internal electronic states of ZnS thin film are measured by means of X-ray diffracti on and X-ray photoemission spectroscopy. The information on the relations between electroluminescent characteristics and internal electronic states of the film is obtained. And the effects of the microstructure of thin film doped with rare earth erbium on electroluminescence are discussed as well. 相关文章 | 计量指标