Table of Content

20 July 1997, Volume 6 Issue 7 Previous Issue    Next Issue

GENERAL

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GENERALLY COVARIANT CONSTITUTIVE EQUATIONS AND OPTICAL METRICS ZHU SHI-TONG, SHEN WEN-DA 1997, 6 (7):  481-487.  doi: 10.1088/1004-423X/6/7/001 Abstract ( 0 )   PDF (125KB) ([an error occurred while processing this directive])   The generally covariant constitutive equations and the corresponding optical metrics for a moving anisotropic medium are first derived. The obtained results reduce to the previous ones for a moving isotropic medium. An extension to any curved space-time is examined.

ATOMIC AND MOLECULAR PHYSICS

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ATOMIC COHERENT POPULATION TRAPPING AND ITS APPLICATION IN A RAMAN-TYPE PHOTOIONIZATION SYSTEM WITH THREE BOUND STATES LI GAO-XIANG, YAN CHENG-NONG, PENG JIN-SHENG 1997, 6 (7):  488-495.  doi: 10.1088/1004-423X/6/7/002 Abstract ( 0 )   PDF (208KB) ([an error occurred while processing this directive])   We have studied the atomic coherent population trapping in a Raman-type, photoionization system with three bound states. The conditions for the system having two or one stable eigenstate are given. The influences of Fano asymmetric factors on the coberent population transfer are also analyzed.It is found that the property of the system having on]y one population trapping state consisting of the ground state, and one excited state, can be utilized to transfer the atomic initial population into one excited state.

CLASSICAL AREAS OF PHENOMENOLOGY

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QUANTUM NONDEMOLITION MEASUREMENTS OF TO PHONONS VIA DETECTING ANTI-STOKES FIELD GUO GUANG-CAN, CHAI JIN-HUA 1997, 6 (7):  496-503.  doi: 10.1088/1004-423X/6/7/003 Abstract ( 0 )   PDF (166KB) ([an error occurred while processing this directive])   A scheme of quantum nondemolition measurement of transverse optical phonons in a Raman crystal is presented through detecting an anti-Stokes field. The exact solutions of the system is obtained. According to the calculation of the criteria for quantum nondemolition measurements, it is shown that under certain conditions the amplitude quadrature component of the phonon mode can be measured without demolition by the phase quadrature component of the anti-Stokes mode.

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PHOTO-INDUCED ENHANCEMENT OF THE THIRD-ORDER OPTICAL NONLINEARITY IN AZOBENZENE COMPOUND ON THE PICOSECOND TIME SCALE WANG YOU-GUI, SI JIN-HAI, YANG QI-GUANG, YE PEI-XIAN, QIU LING, ZHANG JIA-XIN, ZHAI JIAN-FENG, SHEN YU-QUAN 1997, 6 (7):  504-512.  doi: 10.1088/1004-423X/6/7/004 Abstract ( 0 )   PDF (216KB) ([an error occurred while processing this directive])   Photo-induced enhancement processes of the third-order optical nonlinearity were observed in azobenzene solution under a 3Ops pulse pumping at 532 nm. Weinvestigated the time evolotion of the enhancement and found that it was mainly due to thc population of the first excited stale. By theoretical simulation of the enhancement processes, the values of the hyperpolarizabilities of the sample-molecules at ground state and at excited state, γg and γs1 were determined to be 1.11×10-33 esu and 7.40×10-33, respectively.

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

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STUDY OF ANOMALOUS TRANSPORT BY AC MODULATION ON CT-6B TOKAMAK WANG LONG, QI XIA-ZHI, HAN GONG-HE, YANG XUAN-ZONG 1997, 6 (7):  513-516.  doi: 10.1088/1004-423X/6/7/005 Abstract ( 0 )   PDF (86KB) ([an error occurred while processing this directive])   The inward propagation equation of heat wave driven by a weak alternating modulation of the toroidal plasma curent in a tokamak plasma has been exactly solved. Based on this solution, an ac-tive method to determine the electron thermal conduction in a tokamak plasma has been proposed. The thermal conductivity is calculated as a function of minor radius From the soil X-ray data obtained in experiments on thc CT-6B Tokamak. Thc results indicate the anornalous feature of the electron thermal conduction.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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NUCLEATION ENHANCEMENT OF DIAMOND FILMS BY ION BOMBARDING AND ELECTRON EMITTING EFFECTS WANG WAN-LU, LIAO KE-JUN, ZHANG ZHEN-GANG, LIAO MEI-YONG, M.C.POLO, G.SANCHEZ, J.ESTEVE 1997, 6 (7):  517-521.  doi: 10.1088/1004-423X/6/7/006 Abstract ( 0 )   PDF (172KB) ([an error occurred while processing this directive])   Applying a proper negative bias-voltage onto the substrate, on which diamond lilm is deposited by chemical vapor deposition technique, can greatly improve the nucleation density. While nucle-ation enhancing, both the ion bombardment and electron emission may play an important role sepa-rately. However, for the highest nucleation density, both of the two effects must act together.

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

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QUANTUM MECHANICAL EFFECTS OF A MESOSCOPIC CIRCUIT YU ZHAO-XIAN, ZHANG DE-XING, LIU YE-HOU 1997, 6 (7):  522-525.  doi: 10.1088/1004-423X/6/7/007 Abstract ( 0 )   PDF (79KB) ([an error occurred while processing this directive])   The charge and current quantum zero-point fluctuations of an active RLC circuit with squeezed vacuum state are given, and the quantum noise of this circuit at absolute zero temperature is derived.

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FRINGE EFFECT ON CRITICAL CURRENT OF A GOLD FILM PERCOLATION SYSTEM GE HONG-LIANG, ZENG YUE-WU, FENG CHUN-MU, YE GAO-XIANG, ZHANG QI-RUI 1997, 6 (7):  526-530.  doi: 10.1088/1004-423X/6/7/008 Abstract ( 0 )   PDF (144KB) ([an error occurred while processing this directive])   In this paper, the fringe effect on critical current has been studied systematically by measuring the electric transport characteristics of a Au-film system with diffuse fringe structure. It is found experimentally that, when the fringe effect becomes obvious, the film will exhibit strange I-R charac-teristics, in which exist a balance current and a critical current. We find that the critical exponents are related lo the diffuse fringe structure of the Films. The detailed analysis shows that the character- biles result from the thermionic-activating conductive effect in the diffuse fringe film sytem.

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IN SITU STM STUDY OF THERMAL ANNEALING OF Au THIN FILMS:AN INVESTIGATION ON DECAY OF NANOMETER Au CLUSTERS AND 2D ISLANDS LI NAN, D.ALLAN, LIU GANG-YU 1997, 6 (7):  531-549.  doi: 10.1088/1004-423X/6/7/009 Abstract ( 0 )   PDF (939KB) ([an error occurred while processing this directive])   An in situ, ultrahigh vacuum scanning tunneling micrmcopy(UHV STM) study of thermal annealing of gold thin films is presented in this paper. The gold thin films was heated and annealed in the UHV chamber in the temperature range From room temperature to maximum of 300℃, while a consecutive STM imaging was performed on the surface of the gold films during the heating and annealing. The STM results showed that the surface corrugation changes became more apparent after the temperature increased above 100℃, whereas much smoothened surface and large Au (111) crystalline terrace(>200nm) formed at temperature of 160℃ of above. Betides the surface morphology change, our images clearly revealed the melting of multilayer gold clusters and shrinking of monolayer gold islands in a nanometer scale. It was shown that the decay of the gold clusters and islands constitute the microscopic processes contributing to the thermal activated surface morphology change. A classical theory of mass flow kinetics was adopted in analyzing the decay processes. The results showed that surface diffusion is the dominate mechanism in the thermal annealing of the gold thin films. This study presents the first microscopic investigation of thermal annealing processes of metal thin films observed by in situ and real-time STM.