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Table of Content

    20 March 1998, Volume 7 Issue 3 Previous Issue    Next Issue
    CROSSDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
    AL L CORE EDGE FINE STRUCTURE IN Al, AlN AND α-Al2O3:A COMPARISON OF MICROELECTRON ENERGY LOSS SPECTRA WITH THEORY
    X.J.FAN, J.S.BOW, R.W.CARPENTER, S.H.LIN, TIAN SHU-FEN
    1998, 7 (3):  114-226.  doi: 10.1088/1004-423X/7/3/001
    Abstract ( 0 )   PDF (400KB) ([an error occurred while processing this directive])  
    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.
    ATOMIC AND MOLECULAR PHYSICS
    CORE POLARIZATION CORRECTIONS FOR THE PHOTOIONIZATION OF SODIUM
    CHENG YAN-SONG, LIU JIN-CHAO, SUN WEI-GUO
    1998, 7 (3):  161-165.  doi: 10.1088/1004-423X/7/3/002
    Abstract ( 0 )   PDF (144KB) ([an error occurred while processing this directive])  
    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.
    DYNAMIC SCREENING OF THE THREE-BODY COULOMB INTERACTIONS
    CHEN ZHANG-JIN
    1998, 7 (3):  166-173.  doi: 10.1088/1004-423X/7/3/003
    Abstract ( 0 )   PDF (187KB) ([an error occurred while processing this directive])  
    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.
    CLASSICAL AREAS OF PHENOMENOLOGY
    PREPARATION OF NONCLASSICAL STATES OF A CAVITY FIELD BASED ON A NONLINEAR JAYNES-CUMMINGS MODEL
    WEI WEI, GUO GUANG-CAN
    1998, 7 (3):  174-182.  doi: 10.1088/1004-423X/7/3/004
    Abstract ( 0 )   PDF (213KB) ([an error occurred while processing this directive])  
    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.
    COHERENT STATES FOR ONE-DIMENSIONAL INFINITELY DEEP SQUARE POTENTIAL WELL
    NI ZHI-XIANG
    1998, 7 (3):  183-189.  doi: 10.1088/1004-423X/7/3/005
    Abstract ( 0 )   PDF (163KB) ([an error occurred while processing this directive])  
    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.
    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, 7 (3):  190-195.  doi: 10.1088/1004-423X/7/3/006
    Abstract ( 0 )   PDF (165KB) ([an error occurred while processing this directive])  
    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).
    CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
    QUANTUM DIFFUSION IN TWO-DIMENSIONAL OCTAGONAL QUASICRYSTALS
    YUAN HUI-QIU, ZHONG JIAN-XIN
    1998, 7 (3):  196-202.  doi: 10.1088/1004-423X/7/3/007
    Abstract ( 0 )   PDF (208KB) ([an error occurred while processing this directive])  
    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 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.
    OPTICAL PROPERTIES OF ZnO COMPOSITE NANOPARTICLES
    WANG RONG-YAO, WU XIAO-CHUN, WU PENG-FEI, ZOU BING-SUO, WANG LI, XU JING-ZHOU, XU JI-REN, WANG XIN-FENG, WANG ZHEN-JIA, CHEN JIAN-XIN
    1998, 7 (3):  203-208.  doi: 10.1088/1004-423X/7/3/008
    Abstract ( 0 )   PDF (177KB) ([an error occurred while processing this directive])  
    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.
    STUDY OF MICROSTRUCTURE AND ELECTROLUMINESCENCE OF ZINC SULFIDE THIN FILM
    LIU ZHAO-HONG, WANG YU-JIANG, CHEN MOU-ZHI, CHEN ZHEN-XIANG, SUN SHU-NONG, HUANG MEI-CHUN
    1998, 7 (3):  209-113.  doi: 10.1088/1004-423X/7/3/009
    Abstract ( 0 )   PDF (167KB) ([an error occurred while processing this directive])  
    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.
ISSN 1674-1056   CN 11-5639/O4

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