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Volume 6 Issue 2
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Original Articles
CONFORMAL INVARIANT ACTION FOR BOSONIC MEMBRANES AND GAUGE FIXING
HU Hongliang
Chin. Phys. Lett. 1989, 6 (2): 49-52 .  
Abstract   PDF(pc) (46KB) ( 414 )
A conformal invariant action for bosonic membranes is proposed by introducing intrinsic metric on world-tube. It is classically equivalent to the generalised Nambu-Goto action in the sense that the intrinsic metric be viewed at auxilliary field. Gauge fixing through BRST procedure is also carried out.
DIFFEOMORPHISM AND BELTRAM ALGEBRAS ON TORUS
GUO Hanying, SHEN Jianmin, WANG Shikun, XU Kaiwen
Chin. Phys. Lett. 1989, 6 (2): 53-55 .  
Abstract   PDF(pc) (35KB) ( 401 )
The infinite-dimensional algebras on two-dimensional torus are developed. In particular the diffeomorphism algebra and the Beltrami algebra on torus with their central extensions have been presented. It is shown that these algebras are corresponding to the diffeomorphism and the quasiconformal transformation of torus, respectively.
INFLUENCE OF THE ΔΔ CHANNEL WITH THE FBL CONFINEMENT ON THE NN-INTERACTION
SHEN Pengnian, DING Xiaonan, ZHANG Zongye, YU Youwen
Chin. Phys. Lett. 1989, 6 (2): 56-59 .  
Abstract   PDF(pc) (57KB) ( 425 )
The N-N interaction is studied in the framework of non-relativistic quark model using the resonating group method (RGM). The ΔΔ channel is taken into account in addition to the NN channel. The calculated S-wave phase shifts show that the channel coupling effect is increased if the quadratic or the linear confinement is replaced by the Bat-bottom-linear confinement. This result is quite different from that in the case of the quadratic confinement or the linear confinement, in which this channel coupling effect is negligible.
ABSOLUTE MEASUREMENT OF PHOTOIONIZATION CROSS-SECTIONS OF EXCITED STATES 3s5s1S AND 3s4d1D IN MAGNESIUM
HOU Meiying, ZHANG Zuren, LI Jiarning, LIU Lei, NING Xijing*
Chin. Phys. Lett. 1989, 6 (2): 60-63 .  
Abstract   PDF(pc) (57KB) ( 474 )
We report the first experimental investigation of the photoionization cross-sec-tions of singlet excited ststes 3s5s1S and 3s4d1D in atomic magnesium, which can not be directly reached from the ground state. The measured absolute values are σ3s5s1S (571.lnm)=(0.27±0.09)Mb and σ3s4d1D (552. 8nm)=(2.6±0.9)Mb. Theoretical calculations were given, which are in good agreement with the measured values.
OBSERVATION AND MEASURMENT OF THE AUTOIOMZATION SPECTRA OF ATOMIC SAMARIUM
HU Sufen, MEI Shimin, ZHANG Sen, CHEN Xing, XU Yunfei
Chin. Phys. Lett. 1989, 6 (2): 64-67 .  
Abstract   PDF(pc) (54KB) ( 380 )
Autoionization spectra of atomic samarium have been observed using the stepwise laser excitation method. More than fifty autoionizating levels of Sm which are located in the 45793.9- 48045.4cm-1 energy interval with odd parity have been measured.
HIGH POWER TUNABLE COHERENT UV RADIATION BY SUM-FREQUENCY IN β-BaB2O4
XU Zuyan, DENG Daoqun, ZHAO Tienan, WU Baichang*, YOU Guiming*
Chin. Phys. Lett. 1989, 6 (2): 68-71 .  
Abstract   PDF(pc) (50KB) ( 424 )
High power tunable UV coherent radiation has been achieved by sum-frequency generation (SFG) in β-BaB2O4(BBO) crystal. The maximum output power obtained is about 3MW (near 368nm) and 0.75MW (near 222.5nm)
EFFECT OF H+-IONS IMPLANTATION AND Ar+-IONS BOMBARDMENT ON THE PROPERTIES OF LiNbO3 CRYSTAL SURFACES
FENG Xiqi, SHANG Wei
Chin. Phys. Lett. 1989, 6 (2): 72-75 .  
Abstract   PDF(pc) (53KB) ( 374 )
The H+-ions implantation and Ar+-ions bombardment did not cause near-surface decomposition of LiNbO3, but it resulted in the alteration of the physical properties. The XPS (x-ray photoelectron energy spectroscopy) measurement was used to characterize the properties of the radiation damaged surface layer of LiNbO3.
PHOTOLUMINESCENCE STUDIES OF In0.25Ga0.75As-GaAs STRAINED QUANTUM WELLS UNDER HIGH PRESSURE
WANG Lijun, HOU Hongqi, ZHOU Junming, TANG Ruming, LU Zhidong, WANG Yanyun, HUANG Qi
Chin. Phys. Lett. 1989, 6 (2): 76-79 .  
Abstract   PDF(pc) (52KB) ( 418 )
We report the results of the photoluminescence (PL) studies of the In0.25Ga0.75As-GaAs strained quantum wells (QW's) at 77K and at high pressures up to 50kbar. The pressure coefficients of the X valley of (InGa)As-GaAs strained QW's are presented for the first time. The crossover between the energy level in the well and the X valley in the barrier GaAs has been observed. The ratio of the conduction band offset to valence band offset in In0.25Ga0.75As-GaAs heterojunction was determined to be Qc=ΔEc :ΔEv =0.68:0.32. Some discussions about GaAS – Al0.3Ga0.7 As QW's are also presented.
CHARACTERS OF NTD FZ(H2) Si KEPT AT ROOM TEMPERATURE FOR THREE YEARS
MENG Xiangti
Chin. Phys. Lett. 1989, 6 (2): 80-83 .  
Abstract   PDF(pc) (54KB) ( 417 )
It has been found that the hydrogen-defect shallow donors do not appear, and some strong neutron radiation-induced Si-H IR bands, such as 1832 and 2054cm-1 disappear; but the strength of some others, e.g. 1979 and 2065 cm-1 increases greatly for NTD FZ(H2) Si kept at room temperature for 3 years. These changes indicate that at room temperature simple point defects diffuse and interact, and hydrogen atoms trap the vacancy and vacancy cluster defects. This gives important information in the discussion of the micro-structures of the above Si-H IR bands.
SUPERCONDUCTIVITY OF Tl2Ba2 (Ca1-xMgx)2Cu3Oy
WEI Chongde, LIN Qin, SHEN Zhaohui, LIU Zunxiao, LAN Jian, WU Ke, XUE Lixin, DAI Yuandong, GAN Zizhao
Chin. Phys. Lett. 1989, 6 (2): 84-87 .  
Abstract   PDF(pc) (48KB) ( 365 )
The structural, magnetic and superconducting properties of the Tl2Ba2 (Ca1-xMgx)2Cu3Oy system with x=0, 0.05, 0.1, 0.15, 0.2, 0.3, 0.4,0.5 were studied. Replacement of calcium by magnesium depresses Tc from 116.3K (x=0) to 93.3K (x=0.5). The critical current also decreases with increasing x.
THE BEHAVIOR OF 100K SUPERCONDUCTING PHASE IN Pb-doped Bi-Ca-Sr-Cu-O SYSTEM
XIA Jiansheng, FANG Minghu, CAO Liezhao, ZHANG Qirui, CHEN Jian, CHEN Zuyao*, QIAN Yitai*
Chin. Phys. Lett. 1989, 6 (2): 88-91 .  
Abstract   PDF(pc) (58KB) ( 328 )
The ac magnetic susceptibility, the magnetoresistance R(H) and the dependence of the resistivity on temperature under different applied field were investigated in the Pb-doped Bi-Ca-Sr- Cu-O system. A superconducting phase with Tc~100K exists in this sintered sample. It forms a well connecting network, and therefore the Josephson coupling between the superconducting grains is sharply improved by doping lead.
CHEMISORPTION OF OXYGEN ON Au (111) SURFACE
CAO Jianming, WU Naijuan, QI Shangxue, FENG Kean, M.S. ZEI
Chin. Phys. Lett. 1989, 6 (2): 92-95 .  
Abstract   PDF(pc) (0KB) ( 376 )
The chemisorption of oxygen on Au (111) surface has been studied by low energy electron diffraction (LEED) and photoemission spectroscopy (PES). Oxygen was found to begin adsorbed on clean Au(ll1) surface at a temperature above 600°C and an oxygen pressure 5x10-6mbar. The chemisorbed oxygen was very stable and could not be removed by heating up to 85°C . The widening of the Au 4f XPS peak and two new peaks in UPS were observed. The LEED observation showed that a structure with two twisted domains of hexagonal close packed oxide (AuOx) overlayer was formed at the initial oxygen adsorption, and with further oxygen exposure another (√3 x√3 ) R30°structure was formed on the twisted oxide-overlayer.
COMMENT ON SUPERCONDUCTIVITY CAUSED BY STRONG CORRELATION
CHEN Changfeng
Chin. Phys. Lett. 1989, 6 (2): 96-96 .  
Abstract   PDF(pc) (19KB) ( 314 )
13 articles