Table of contents

20 March 1998, Volume 7 Issue 3 Previous issue    Next issue

CROSS DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

Select

AL L CORE EDGE FINE STRUCTURE IN Al, AlN AND $\alpha$-Al2O3：A COMPARISON OF MICROELECTRON ENERGY LOSS SPECTRA WITH THEORY X.J.FAN (樊锡君), J.S.BOW, R.W.CARPENTER, S.H.LIN, TIAN SHU-FEN (田淑芬) Acta Physica Sinica (Overseas Edition), 1998, 7 (3):  214-226.  DOI: 10.1088/1004-423X/7/3/009 Abstract ( 1107 )   PDF (400KB) ( 324 )   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

Select

CORE POLARIZATION CORRECTIONS FOR THE PHOTOIONIZATION OF SODIUM CHENG YAN-SONG (程延松), LIU JIN-CHAO (刘锦超), SUN WEI-GUO (孙卫国) Acta Physica Sinica (Overseas Edition), 1998, 7 (3):  161-166.  DOI: 10.1088/1004-423X/7/3/001 Abstract ( 1352 )   PDF (144KB) ( 367 )   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.

Select

DYNAMIC SCREENING OF THE THREE-BODY COULOMB INTERACTIONS CHEN ZHANG-JIN (陈长进) Acta Physica Sinica (Overseas Edition), 1998, 7 (3):  167-173.  DOI: 10.1088/1004-423X/7/3/002 Abstract ( 1183 )   PDF (187KB) ( 341 )   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

Select

PREPARATION OF NONCLASSICAL STATES OF A CAVITY FIELD BASED ON A NONLINEAR JAYNES-CUMMINGS MODEL WEI WEI (魏渭), GUO GUANG-CAN (郭光灿) Acta Physica Sinica (Overseas Edition), 1998, 7 (3):  174-182.  DOI: 10.1088/1004-423X/7/3/003 Abstract ( 1172 )   PDF (213KB) ( 359 )   It is proven in this paper that some kinds of nonclassical quantum states of the cavity field, such as Schr$\ddot{\rm o}$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.

Select

COHERENT STATES FOR ONE-DIMENSIONAL INFINITELY DEEP SQUARE POTENTIAL WELL NI ZHI-XIANG (倪致祥) Acta Physica Sinica (Overseas Edition), 1998, 7 (3):  183-189.  DOI: 10.1088/1004-423X/7/3/004 Abstract ( 1278 )   PDF (163KB) ( 370 )   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.

Select

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 Acta Physica Sinica (Overseas Edition), 1998, 7 (3):  190-195.  DOI: 10.1088/1004-423X/7/3/005 Abstract ( 1145 )   PDF (165KB) ( 442 )   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($\lambda$ = 255 nm), 0.9×10-9 cm-1·Pa-1($\lambda$ = 271 nm), and 1.6×10-9cm-1 ·Pa-1($\lambda$ = 289 nm).

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

Select

QUANTUM DIFFUSION IN TWO-DIMENSIONAL OCTAGONAL QUASICRYSTALS YUAN HUI-QIU (袁辉球), ZHONG JIAN-XIN (钟建新) Acta Physica Sinica (Overseas Edition), 1998, 7 (3):  196-202.  DOI: 10.1088/1004-423X/7/3/006 Abstract ( 1293 )   PDF (208KB) ( 388 )   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-$\delta$ with 0＜$\delta$≤1. The scaling factor $\delta$ is related to Hamiltonian parameters and the type of site where electron is initially located. Moreover, we find a crossover from $\delta$=1 to 0＜$\delta$＜1 with increasing site potentials.

Select

OPTICAL PROPERTIES OF ZnO COMPOSITE NANOPARTICLES WANG RONG-YAO (王荣瑶), WU XIAO-CHUN (吴晓春), WU PENG-FEI (武鹏飞), ZOU BING-SUO (邹炳锁), WANG LI (汪力), XU JING-ZHOU (许景周), XU JI-REN (徐积仁), WANG XIN-FENG (王新峰), WANG ZHEN-JIA (王振家), CHEN JIAN-XIN (陈建新) Acta Physica Sinica (Overseas Edition), 1998, 7 (3):  203-208.  DOI: 10.1088/1004-423X/7/3/007 Abstract ( 1632 )   PDF (177KB) ( 413 )   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.

Select

STUDY OF MICROSTRUCTURE AND ELECTROLUMINESCENCE OF ZINC SULFIDE THIN FILM LIU ZHAO-HONG (柳兆洪), WANG YU-JIANG (王余姜), CHEN MOU-ZHI (陈谋智), CHEN ZHEN-XIANG (陈振湘), SUN SHU-NONG (孙书农), HUANG MEI-CHUN (黄美纯) Acta Physica Sinica (Overseas Edition), 1998, 7 (3):  209-213.  DOI: 10.1088/1004-423X/7/3/008 Abstract ( 1204 )   PDF (167KB) ( 470 )   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.