Table of contents

20 May 1993, Volume 2 Issue 5 Previous issue    Next issue

GENERAL

Select

APPLYING THE HOMOTOPY EQUIVALENCE TRANSFORMATION OF TOPOLOGICAL SPACE SETS TO THE TOPOLOGICAL CLASSIFICATION OF STATES AND DEFECTS IN ORDERED MEDIA LI BO-ZANG (李伯臧), YAN FENG-LI (阎凤利) Acta Physica Sinica (Overseas Edition), 1993, 2 (5):  321-332.  DOI: 10.1088/1004-423X/2/5/001 Abstract ( 1135 )   PDF (321KB) ( 395 )   In this paper the application of homotopy equivalence transformation (HET) of topological space sets to the topological classification of states and defects in ordered media is discussed. Firstly, an argument is pres-ented about the idea that for simplifying and even working out the classification and constructing homotopy class sets into groups, it is crucial to utilize the HET. As the theoretical basis for doing this we sum up the relevant results in homotopy theory into a theorem, called the "invariance theorem for HET". Secondly, in order to favor the utilization of this theorem, several propositions on homotopy equivalence between space sets are given. Finally, the absolute and relative topological dassification of states and defects is systemtically studied. The main results obtained are embodied in eight theorems.

ATOMIC AND MOLECULAR PHYSICS

Select

QUANTUM EFFICIENCY AND MULTIPHONON NONRADIATIVE TRANSITION OF Er3+ IONS IN FLUORIDE GLASS JIANG XUE-YIN (蒋雪茵), ZHANG ZHI-LIN (张志林), XU SHAO-HONG (许少鸿) Acta Physica Sinica (Overseas Edition), 1993, 2 (5):  333-344.  DOI: 10.1088/1004-423X/2/5/002 Abstract ( 1268 )   PDF (274KB) ( 409 )   Optical absorption, emission and excitation spectra, lifetimes of 4S3/2 state and 4F9/2 state from 10K to 500K, and Raman spectra were measured for Er3+ ions in fluoride glass. The radiative transition probabilities were calculated on the basis of Judd-Ofelt theory. The nonradiative transition probabilities and the quantum efficiencies were determined by calculating the difference between the measured lifetimes and the calculated radiative transition probabilities. The temperature dependence of nonradiative transition provavility was investigated using the Huang-Rhys theory of multiphonon relaxation , in which two kinds of phonons as well as the parameter s were taken into consideration. A fairly good agreement of the theoretical calculation with the experimental results has been obtained. The value of s is estimated and the effect of s is discussed.

Select

EFFECT OF THE LASER TRANSVERSE SPATIAL DISTRIBUTION ON MULTIPHOTON IONIZATION PROCESSES LIN MEI-RONG (林美荣), CHEN WEN-JU (陈文驹), ZHANG BAO-ZHENG (张包铮), LIU YAO-MING (刘耀明), LI LIN-FENG (李林枫) Acta Physica Sinica (Overseas Edition), 1993, 2 (5):  345-355.  DOI: 10.1088/1004-423X/2/5/003 Abstract ( 1001 )   PDF (233KB) ( 359 )   In this paper, the dependence of the photoionization cross section $\sigma$2, total ion number Ni and the FWHM of photoionization spectral line in resonant multiphoton ionization processes (RMPI) upon the parameter C of the laser transverse spatial distribution has been studied. Considering the effects of spatial coordinate on the resonant multiphoton absorption cross section $\sigma$1, the limited dimension of the laser-molecular interaction volume and threshold of laser intensity for RMPI, we deduce the expression of $\sigma$2 vs the parameter C. We calculated the value of $\sigma$2 for (2+2)PI of benzene by numerical method, and com-pared the result with that obtained by Bruzzeste et al. In additon, we also present the total ion number of photoionization and the FWHM of photoionization spectral line as a function of the parameter C.

CLASSICAL AREAS OF PHENOMENOLOGY

Select

THE TRANSMISSION PROPERTIES OF SOLITON ON THE CW BACKGROUND NEAR THE ZERO-DISPERSION WAVELENGTH LIANG CHANG-HONG (梁昌洪), WU HONG-SHI (吴鸿适), CHEN LU-JUN (陈陆君) Acta Physica Sinica (Overseas Edition), 1993, 2 (5):  356-364.  DOI: 10.1088/1004-423X/2/5/004 Abstract ( 1087 )   PDF (221KB) ( 400 )   By using the perturhation theory and small-amplitude approximation with the self-induced Raman effect and the loss as well as gain of the fiber taken into account, the transmission properties of solitons in the nomal dispersion region near the zero-group-dispersion wavelength are analytically investigated in this paper. The result shows that not only the small-amplitude dark soliton but also the small-amplitude bright soliton may exist in the normal dispersion region near the zero-group-dispersion point. Their stabilities depend on the propagating direction and the region in which they are situated in the parameter-space. The conversion between bright and dark solitons may be realized by controlling the relative intensities of gain and loss along the fiber. This may be applied to the logic or arithmetic devices in the integrated optical circuit.

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

Select

THE INTERACTION OF Au AND THE Si/SiO2 INTERFACE DEFECT Hit(0.494) LIU HONG-FEI (刘鸿飞), CHEN KAI-MAO (陈开茅), YUAN MIN-HUA (元民华), WU LAN-QING (武兰青) Acta Physica Sinica (Overseas Edition), 1993, 2 (5):  365-375.  DOI: 10.1088/1004-423X/2/5/005 Abstract ( 1498 )   PDF (289KB) ( 405 )   The defects at the Si/SiO2 interface have been studied by the deep-level transient spectroscopy (DLTS) technique in p-type MOS structures with and without gold diffusion. The experimental results show that the interaction of gold and Si/SiO2 interface defect, Hit(0.494), results in the formation of a new interface de-fect, Au-Hit(0.445). Just like the interface defect, Hit(0.494), the new interface defect possesses a few interesting properties, for example, when the gate voltage applied across the MOS structure reduces the energy interval between Fermi-level and Si valence band of the Si surface to values smaller than the hole ionization Gibbs free energy of the defect, a sharp DLTS peak is still observable; and the hole apparent activation energy increases with the decrease of the Si surface potential barrier height. These properties can be successfully explained with the transition energy band model of the Si/SiO2 interface.

Select

FORMATION OF A BURIED LAYER OF ALUMINIUM NITRIDE BY HIGH DOSE N2+ IMPLANTATION INTO ALUMINIUM LIN CHENG-LU (林成鲁), P.L.F.HEMMENT, LI JIN-HUA (李金华), SHI ZUO-YU (施左宇), Y.LI, J.A.KILNER Acta Physica Sinica (Overseas Edition), 1993, 2 (5):  376-385.  DOI: 10.1088/1004-423X/2/5/006 Abstract ( 1208 )   PDF (250KB) ( 401 )   Aluminium films with various thickness between 700 nm and 1μm were deposited on Si (100) substrates, and 400 keV N2+ ions with doses ranging from 4.3×1017 to 1.8×1018 N/cm2 were implanted into the alu-minium films on silicon, Rutherford Backscattering (RBS) and channeling, secondary ion mass spectroscopy (SIMS), Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and spreading resistance probes (SRP) were used to characterize the synthesized aluminium nitride. The experiments showed that when the implantation dose was higher than a critical dose Nc, a buried stoichiometric AlN layer with high resistance was formed, while no apparent AlN XRD peaks in the as-implanted samples were observed; however, there was a strong AlN(100) diffraction peak appearing after annealing at 500 ℃ for 1h. The computer program, Implantation of Reactive Ions into Silicon (IRIS), has been modified and used to simulate the formation of the buried AlN layer as N2+ is implanted into aluminium. We find a good agreement between experimental measurements and IRIS simulation.

Select

THE EFFECT OF LATTICE VIBRATION ON THE MAGNETISM IN METALLIC HYDROGEN WU JIAN-HUA (吴建华), LI BO-ZANG (李伯臧), WANG JI-FANG (王积方) Acta Physica Sinica (Overseas Edition), 1993, 2 (5):  386-391.  DOI: 10.1088/1004-423X/2/5/007 Abstract ( 1092 )   PDF (140KB) ( 417 )   In this note, a new approach is adopted to the magnetism in metallic hydrogen, i.e., based on the Kim theory and Stoner model the electron-phonon interaction is introduced into the itinerant electron mag-netism theory. A calculation of spontaneous magnetization of metallic hydrogen at T=0 K shows that in spite of no change in the para- to ferro-magnetism value, rsc of W-S radius rs, the spontaneous magnetic moment of electron in ferromagnetic state, where rs>>rsc, is considerably reduced by lattice vibrations.