Table of Content

20 June 1994, Volume 3 Issue 6 Previous Issue    Next Issue

ATOMIC AND MOLECULAR PHYSICS

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STUDY OF THE POLARIZATION SPECTROSCOPY OF 3p RYDBERG STATES OF m-DIMETHYLBENZENE LIU YAO-MING, LIN MEI-RONG, ZHANG BAO-ZHENG, ZHAO QING-CHUN, CHEN WEN-JU 1994, 3 (6):  401-405.  doi: 10.1088/1004-423X/3/6/001 Abstract ( 0 )   PDF (156KB) ([an error occurred while processing this directive])   A polarization-selected three-photon resonant multiphoton ionization investigation of the 3p Rydberg region of the spectra of m-dimethylbenzene has been conducted. Several vibronic states have been discovered and also assigned for the first time.

CLASSICAL AREAS OF PHENOMENOLOGY

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ANALYSIS OF THE LASER-INDUCED FLUORESCENCE IN CRYSTAL Cr:Mg2SiO4 GUO XIANG-YI, YANG BAO-CHENG, SHEN GUO-TU, LIN YUAN-QI, ZHU SHENG-XIANG, PAN PEI-CONG 1994, 3 (6):  406-412.  doi: 10.1088/1004-423X/3/6/002 Abstract ( 0 )   PDF (190KB) ([an error occurred while processing this directive])   Observation of the 532 nm-laser-induced fluorescence spectra of two kinds of Cr:Mg2SiO4 crystalline samples grown in different atomsphere are reported. The experiments were con-ducted at both room temperature and liquid-nitrogen temperature. The fluorescence spectra of the two kinds of samples were different with respect to the polarizing direction of the inducing leser, and two emission bands with different polarized characters and various en-hancement in intensity at low temperatures were also found. In the light of the calculated results by Ms-Xα method, the main experimental results are explained.

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INTERSUBBAND OPTICAL ABSORPTION IN SEMICONDUCTOR SUPERLATTICES WITH COMPLEX BASES SHI JUN-JIE, DAI XIAN-QI, PAN SHAO-HUA 1994, 3 (6):  413-425.  doi: 10.1088/1004-423X/3/6/003 Abstract ( 0 )   PDF (274KB) ([an error occurred while processing this directive])   The third-order nonlinear intersubband optical absorption coefficient within the con-duction band of semiconductor superlattices with complex bases have been calculated using the density matrix formalism including intrasubband and intersubband relaxation. The sub-band dipole moments zij(k) and zii(k) are first studied in superlattices with complex bases including a general coupled-well basis and a general step-well basis. The results show that zij(k) and zii(k) are complicated functions of and strongly depends on the well parameters. The intersubband transition optical absorption coefficient α(ω,I) is further studied. The numerical illustrations are also given.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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ELECTRICAL RESISTIVITY OF NANOCRYSTALLINE Fe-Cu-Si-B ALLOYS LIU XUE-DONG, LU KE, DING BING-ZHE, HU ZHUANG-QI, WANG YONG-ZHONG 1994, 3 (6):  426-430.  doi: 10.1088/1004-423X/3/6/004 Abstract ( 0 )   PDF (154KB) ([an error occurred while processing this directive])   We have studied the room temperature and low-temperature electrical resistivities of nanocrystalline Fe-Cu-Si-B alloys with various grain sizes prepared by crystallization of amor-phous material. Experimental results showed that with the reduction of grain size both room temperature resistivity ρRT and residual reaistivity ρ0 of the nanostructured alloys studied increased significantly. Based on the scattering effects from interfaces and lattice distortion, the above results were qualitatively discussed.

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SIMULATION OF X-RAY DIFFRACTION OF MULTILAYER FILM WITH INTERFACIAL ROUGHNESS GAO CHEN, LIU WEN-HAN, WU ZI-QIN 1994, 3 (6):  431-438.  doi: 10.1088/1004-423X/3/6/005 Abstract ( 0 )   PDF (216KB) ([an error occurred while processing this directive])   In this paper, the X-ray diffraction profiles of multilayer with uncorrelated rough interfaces are directly simulated using kinematic theory of X-ray diffraction. The result shows that the decrease of the reflective intensity caused by the interracial roughness is more severe than that caused by random fluctuation of period of the same degree, and the decrease of the reflective intensity of high order Bragg deffraction is more rapid than that of low order ones. So it is very important to reduce the interracial roughness in the deposition and in the annealing of multilayer films.

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RADIATION-INDUCED DEFECTS IN RADIATION HARD AND SOFT OXIDES LIU CHANG-SHI, MA ZHONG-QUAN, ZHAO YUAN-FU 1994, 3 (6):  439-444.  doi: 10.1088/1004-423X/3/6/006 Abstract ( 0 )   PDF (166KB) ([an error occurred while processing this directive])   The point defects of Pb and E′ in radiation hard and soft Si-SiO2 samples were examined using electron spin resonance (ESR). The experimental results showed that these defects were correlated with the ways of oxidation process, the dosage of 60Co radiation and the radiation bias field. Besides, the ΔH (peak of peak) of Pb and E′ indicated that Pb is the defect with slow electron spin relaxation time while E′ is the defect with fast electron spin relaxation time. Finally, the experimental results are explained qualitatively.

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

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PROPERTIES OF TEMPERATURE DEPENDENCE OF THRESHOLD IN PURE AND IMPUHITY-DOPED BLUE BRONZES TIAN MING-LIANG, MAO ZHI-QIANG, ZHANG YU-HENG, ZHANG YI-MIN, SHI JING, TIAN DE-CHENG 1994, 3 (6):  445-452.  doi: 10.1088/1004-423X/3/6/007 Abstract ( 0 )   PDF (210KB) ([an error occurred while processing this directive])   Temperature dependence of the threshold of pure and impurity-doped blue bronzes has been studied. It is found that for pare blue bronzes the threshold field near 100K has an anomalous peak, but for impurity-doped samples no anomaly is observed in the range of liquid nitrogen temperature, and the value of the threshold field gradu-ally increases with the decrease of temperature. The results show that in the high-quality pure blue bronzes, there may exist an incommensurate to quasi-commensurate transition near 100K. But for the impurity-doped or "dirty" pure samples, such an incommensurate to quasi-commensurate transition near 100K can be extensively re-strained by impurities or defects, which leads to a pure incommensurate CDW in a wide temperature range.

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FAR-INFRARED PHOTOCONDUCTIVITY MECHANISM ON SHALLOW IMPURITY IN GaAs CHEN ZHONG-HUI, LIU PU-LIN, ZHOU TAO, SHI GUO-LIANG, LU WEI, HUANG XING-LIANG, SHEN XUE-CHU 1994, 3 (6):  453-459.  doi: 10.1088/1004-423X/3/6/008 Abstract ( 0 )   PDF (196KB) ([an error occurred while processing this directive])   We report the far-infrared photoconductivity spectroscopy (FIRPCS) of the high purity n-GaAs grown by molecular beam epitaxial (MBE) technique. The current-voltage (I-V) measurement and FIRPCS under different electric field strength have been performed on high purity n-GaAs at 4.2K. Except for photothermal ionization process, a new far-infrared photoconductivity (FIRPC) mechanism is observed. This photo ionization process is assisted by impact ionization and depends on external electric field. This new mechanism originates from photo-field ionization.

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MAGNETIC PROPERTIES OF NEW SERIES R-Mo-Fe NITRIDES WITH THE ThMn12-TYPE STRUCTURE AT A LOWER Mo CONTENT PAN QI, ZHANG XIAO-DONG, ZHANG MING-HOU, YANG YING-CHANG 1994, 3 (6):  460-469.  doi: 10.1088/1004-423X/3/6/009 Abstract ( 0 )   PDF (262KB) ([an error occurred while processing this directive])   A systematic study has been made on formation condition, crystallographic structure and magnetic properties of RMo1.5Fe10.5Nx, where R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er. The interstitial nitrogen atom effects on Curie temperature, saturation magnetization and magneto-crystalline anisotropy have been investigated. Two important preliminary results have been obtained. (1) A single phase crystallized in the ThMn12-type structure was stabilized with a smaller content of molybdenum, thus, the compounds possess a higher Curie temperature and a larger spontaneous magnetization. (2) A complete system of compounds with 1:12 type structure containing the light rare earth cerium and praseodymium was synthesized, which will be favorable for developing new rare earth hard magnetic materials.