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Volume 6 Issue 12
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Original Articles
DETECTION OF 36C1 WITH A ACCELERATOR MASS SPECTROMETRY
JIANG Songsheng, MA Tiejun, JIANG Shan, YANG Bingfan, WANG Xun, HUANG Qi*
Chin. Phys. Lett. 1989, 6 (12): 529-532 .  
Abstract   PDF(pc) (58KB) ( 409 )
An accelerator mass spectrometry (AMS) system based on the HI-I3 tandem accelerator at the Institute of Atomic Energy (IAE) is described, and the first detection of 36C1 with our AMS system is reported. The electrostatic deflector completely rejects isotopic background, 35C1 and 37C1. The ionization chamber distinguishs 36C1 from isobaric background, 36S. The measurement of 36C1 with two samples is presented.
AN ANALYTICAL CALCULATION FOR THE LASER GAIN IN A LONG PULSE FREE-ELECTRON LASER
JIA Qika
Chin. Phys. Lett. 1989, 6 (12): 533-536 .  
Abstract   PDF(pc) (57KB) ( 368 )
For a long pulse free-electron laser (FEL) in the low gain regime, an approximate expression is given to describe the optical field gain from the small signal to the weak saturation. The result is shown to agree with those from a 1-D computer simulation.
NON-PROPAGATING SOLITARY SURFACE WAVE IN AN ANNULAR TROUGH
YAN Jiaren, YANG Xin e*
Chin. Phys. Lett. 1989, 6 (12): 537-540 .  
Abstract   PDF(pc) (47KB) ( 309 )
The nonlinear equation governing the nonpropagating solitary surface wave and its single solitary wave solution were derived by the method of multiple scales. The results obtained were compared with that in rectangular trough.
POSSIBLE EXPLANATION OF THE PLATEAU WIDTH IN THE QUANTUM HALL EFFECT AT FINITE TEMPERATURE
HUANG Fengyi
Chin. Phys. Lett. 1989, 6 (12): 541-545 .  
Abstract   PDF(pc) (60KB) ( 447 )
The finite width of the plateau in the Hall resistance is studied quantitatively. If we give a filling factor v, the ratio of the plateau width ΔB to the center of the plateau BH square is constant for all other filling factors v' if v'=v+m with m any integer. The temperature dependence of the plateau width is also studied. Theoretical results are in good agreement with the data obtained from experiment.
CHARACTERIZATION OF Si-SiO2 INTERFACE STATES IN MOS CAPACITORS BY USING DLTS TECHNIQUE
LU Liwu*, G.Groesendken, C.Hasenack
Chin. Phys. Lett. 1989, 6 (12): 545-548 .  
Abstract   PDF(pc) (62KB) ( 437 )
The Dit (interface states density) in p-type MOS capacitors subjected to a preoxidation heat treatment was investigated by using DLTS (Deep Level Transient Spectroscopy) technique. It is found that the strong dependence of the Dit on POHT (Preoxidation Heat Treatment) and starting oxygen content of substrates is expected. The DLTS technique can detects the presence of bulk defect (Et-Ev=0.29eV) at the interface presumably due to chlorine species.

TEMPERATURE DEPENDENCE OF POSITRON ANNIHILATION PARAMETERS IN HIGH Tc SUPERCONDUCTOR YBa2Cu3O7-x
LI Anli, ZHENG Shengnan, HUANG Hanchen, LI Donghong, DU Hongshan, DIN Honglin, SUN Hancheng, ZHU Shengyun
Chin. Phys. Lett. 1989, 6 (12): 549-552 .  
Abstract   PDF(pc) (51KB) ( 357 )
The temperature dependences of the positron annihilation lifetime and the Doppler broadening shape parameters have been measured in high Tc superconductors YBa2Cu3O7-x = between 77.2 and 300K. The measured parameters show an abrupt change across the range of superconducting transition temperature, indicating a change of the electronic structure. The structural instabilities have also been observed in three higher temperature ranges of115-135, 150-210 and 250-280K. This suggests that higher Tc superconductors might be found in these temperature ranges.

SUPERCONDUCTIVITY IN GLASSY Bi-Sr-Ca-Cu-O SYSTEM
LIN Rong, CHEN Xianhui, CHEN Zuyao, QIAN Yitai, XIA Jiansheng*, WANG Shunxi*, ZHANG Qirui*
Chin. Phys. Lett. 1989, 6 (12): 553-556 .  
Abstract   PDF(pc) (54KB) ( 440 )
To explore high Tce in Bi-Sr-Ca-Cu-O system, many different nominal compositions have been investigated. Zero resistance temperature Tce as high as 105K and only one sharp 3uperconducting transition in a.c. susceptibility measurement has been observed in the nominal composition Bi2Sr2Ca3Cu4Oy by using the method of crystallization from glassy Bi-Sr-Ca-Cu-O at 875°C for above 50h.

CRYSTAL GROWTH AND SPECTROSCOPIC PROPERTIES OF LaMgAl11O19:Nd3+
XU Jun, MA Xiaoshan, ZHANG Xiurong, SHEN Yafang, ZHANG Xinmin
Chin. Phys. Lett. 1989, 6 (12): 557-558 .  
Abstract   PDF(pc) (32KB) ( 401 )
The Czochralski growth of LaMgAl11O19:Nd3+ crystal is investigated. Its temperature fluorescence and absorption spectra are measured.

TIME-RESOLVED PHOTOLUMINESCENCE FROM InxGa1-xAs/GaAs SINGLE QUANTUM WELL
QIAN Shixiong, YUAN Shu, LI Yufen, T.G .Andersson, CHEN Zonggui, PENG Wenji, YU Zhenxin
Chin. Phys. Lett. 1989, 6 (12): 559-562 .  
Abstract   PDF(pc) (64KB) ( 440 )
We have measured the time-resolved photoluminescence spectra of several InxGa1-xAs/GaAs single quantum well samples at 77K. The different temporal behaviors of the photoluminescence (PL) from the GaAs layer and the excitonic emission from the InxGa1-xAs well were obtained. The lifetime for the exciton in the InxGa1-xAs well were determined to be 110-170ps. The trapping efficiency of the well to the carriers was about 80%.
PREPARATION AND CHARACTERIZATION OF HEAVILY DOPED μc-Si:F:H FILMS BY WINDOWLESS PHOTO-CVD
GUO shuwen, TAN shongsheng, WANG Weiyuan,
Chin. Phys. Lett. 1989, 6 (12): 563-565 .  
Abstract   PDF(pc) (52KB) ( 330 )
A novel μc-Si:F:H film growth technique has been developed using a windowless photo-enhanced chemical vapor deposition (photo-CVD) system. The films contain of two phases with the microcrystallites embedded in amorphous materials. The films contain the crystallites with volume of fraction of 0.17-0.23 and average grain size of 32-85nm. The conductivity up to 16(Ω.cm)-1 and gauge factor (GF) of about 12 are obtained.
STELLAR WINDS AND MOLECULAR OUTFLOWS
MAO Xinjie, SUN Jin, LI Songzhong*, WU Yuefang*
Chin. Phys. Lett. 1989, 6 (12): 566-569 .  
Abstract   PDF(pc) (59KB) ( 298 )
We develop a model to explain the high velocities of the ionized stellar winds around young stellar objects associated with magnetic fields. The plasma which is produced by the hot object nearby is turbulent and plays a significant role to accelerate particles. Then the high velocity winds encounter the ambient gas in a molecular cloud to form shock waves. The shocked gas emmision produces broad wings of CO line profiles.

ARCS FROM COSMIC STRINGS AS GRAVITATIONAL LENSES
WU Xiangping
Chin. Phys. Lett. 1989, 6 (12): 570-572 .  
Abstract   PDF(pc) (36KB) ( 337 )
A numerical calculation is made to find the arc images of background galaxies produced by cosmic strings(1oops) as lensing objects. The result shows that there should be several medium-sized arcs for each long arc discovered and further work should be done to distinguish cosmic string from galaxy cluster as deflector.
12 articles