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Volume 8 Issue 7
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Original Articles
Testing the Intermediate-Range Force at Separations Around 50 Meters
YANG Xinshe, LIU Wuming, ZHAO Hailong, LI Jingtian
Chin. Phys. Lett. 1991, 8 (7): 329-332 .  
Abstract   PDF(pc) (207KB) ( 551 )
We use a LaCoste-Romberg model D gravimeter to measure the gravitational forces at fixed positions when a large cylindrical reservoir is full and when it is empty. The differences determine the intermediate-range force at various separations around 50m to about 0.5 % accuracy.
Atomic Motion in a Misaligned Standing-Wave Field
WANG Yuzhu*, LIU Liang, CAI Weiquan, CHENG Yudan
Chin. Phys. Lett. 1991, 8 (7): 333-336 .  
Abstract   PDF(pc) (178KB) ( 432 )
Theoretical and experimental results of laser cooling and laser heating of an atomic beam in a standing-wave field and in a misaligned standing-wave field are reported. The results show that in strong fields, laser heating in a standing-wave field become laser cooling in a misaligned standing-wave field and in weak fields, laser cooling become more efficient in a standing-wave field than in a misaligned standing-wave field.
Focusing Properties of Short Space-Charge Lenses
YU Qingchang, QIU Hong, SHU Chuanyu, JIANG Fuyou
Chin. Phys. Lett. 1991, 8 (7): 337-340 .  
Abstract   PDF(pc) (161KB) ( 439 )
The electron densities in a short space-charge lens are measured with the radiofrequency method under different applied magnetic inductions and voltages, and relations between the focusing power of the lens and the external electromagnetic fields are investigated.
Squeezing Enhancement of an Initially Squeezed Electromagnetic Field in Two-photon Interaction Dicke Model
ZHOU Yidong, LI Shiqun, CHEN Tianjie*
Chin. Phys. Lett. 1991, 8 (7): 341-344 .  
Abstract   PDF(pc) (145KB) ( 525 )
The evolution of an initially squeezed electromagnetic field was studied by using two-photon interaction Dicke model and pertubation approach. It was found that under certain condition in two-photon Dicke model squeezing will be enhanced. The physical insight of this phenomenon is discussed.
Gas Multiplication in the Proportional Region
TANG Xiaowei
Chin. Phys. Lett. 1991, 8 (7): 345-347 .  
Abstract   PDF(pc) (139KB) ( 564 )
A simplified model of gas multiplication in the proportional region is proposed. A linear relationship between In A and V is derived. The formulae relating the macroscopic parameters of proportional region with the microscopic parameters of gas multiplication are obtained. By analyzing the experimental data the values of these parameters under different conditions are determined.
Growth of Diamond Films by Microwave Plasma Chemical Vapor Deposition
GAO Kelin, WANG Chunlin, ZHAN Rujuan, PENG Dingkun, MENG Giangyao, XIANG Zhilin
Chin. Phys. Lett. 1991, 8 (7): 348-351 .  
Abstract   PDF(pc) (170KB) ( 453 )
Diamond thin films were produced by microwave plasma chemical vapor deposition. The deposit is identified by X-ray diffraction, Raman spectroscopy and Scanning electron microscopy. During the course of diamond growth, the characteristics of the plasma have been measured by means of the Langmuir double probe and emission spectrometer.
Trapped Particle Effect on Ion Cyclotron Radiofrequency Heating
CHEN Yanping, CAI Shidong (TSAI shihtung)*
Chin. Phys. Lett. 1991, 8 (7): 352-355 .  
Abstract   PDF(pc) (152KB) ( 358 )
A nonlocal theory for trapped ion absorption in ion cyclotron radiofrequency heating is developed. The gyrokinetic equation is adopted and a full partied orbit and wave coupling is kept.
Braggs Law with Refractive Correction of Low-angle X-ray Diffraction for Periodic Multilayers
JIANG Xiaoming, WU Ziqin*
Chin. Phys. Lett. 1991, 8 (7): 356-359 .  
Abstract   PDF(pc) (170KB) ( 1081 )
Bragg's law with refractive correction of low-angle X-ray diffraction for periodic multilayers is deduced according to the optical refractive law and interference rules. Variant forms of this law, which accorded with experiments quite well, are given.
Fabrication of Polar Films by Langmuir-Blodgett Technique
FANG Jiyu, WEI Yu, SUN Zhengmin*
Chin. Phys. Lett. 1991, 8 (7): 360-363 .  
Abstract   PDF(pc) (176KB) ( 484 )
The polar films of liquid crystal(8CB) with large dipole moment have been fabricated by the Langmuir-Blodgett technique. The pyroelectric effects in the polar structure have been observed by the static method. The static pyro-electric coefficients depend on the temperature of the sample and the surface pressure of aqueous subphase during the deposition of monolayers.

Interfacial Properties of a-Si:H/a-SiNx:H Multilayers Studied by electroabsorption Spectroscopy
LIU Xiangna, ZHAO zhouying, WANG Yong, LI Wenkai
Chin. Phys. Lett. 1991, 8 (7): 364-367 .  
Abstract   PDF(pc) (199KB) ( 305 )
By using electroabsorption method, we find that the built-in field (~105 V.cm-1) in the a-Si sublayers of a-Si:H/a-SiNx:H multilayers points towards the sample surfaces. We ascribe the internal field to the asymmetric distribution of defect states which exist primarily in the silicon side of the silicon-on-nitride interfaces, owing to the large repellent lattice stress there. We also find that the built-in potential depends strongly on x, with a maximum value near x = 1.0. We intend to explain it as a result of structural softening as more N atoms are introduced into Si networks in the range of x > 1.0.
Radiation Effect on YBa2Cu3O7-δ by 35 MeV Proton Irradiation
YU Jinnan, GAO Zhongcai, WANG Yuzhu, CHEN Yiren, SHI Yuemei
Chin. Phys. Lett. 1991, 8 (7): 368-371 .  
Abstract   PDF(pc) (194KB) ( 381 )
The specimens of YBa2Cu3O7-δ are irradiated by 35 MeV proton at 70K, the sero-resistance temperature TC0 is increased with the proton fluence within the range (2.21 x 1013-1.77 x 1014p/cm2). Tc0 is increased from 91 to 97K at the fluence 1.77 x 1014p/cm2 and critical current is also enhanced.
Magnetic Properties of NdTiFe11N0.5 and YTiF11N0.5
YANG Yingchang, ZHANG Xiaodong, PAN Qi, KONG Linshu
Chin. Phys. Lett. 1991, 8 (7): 372-375 .  
Abstract   PDF(pc) (177KB) ( 408 )
The structural and magnetic properties of NdTiFe11N0.5 and YTiFe11N0.5 have been studied. The nitrides retain the tetragonal ThMn12 structure and their unit cell volumes slightly increase. The interstitial nitrogen atoms are found to increase the Curie temperature and saturation magnetization of the compounds, and especially have a strong effect on the magnetocrystalline anisotropy.
In-situ Raman Scattering Study of Stage Transformation in HC1O4-Graphite Intercalation Compounds
LAN Guoxiang, LIU Daozhi, WANG Huafu
Chin. Phys. Lett. 1991, 8 (7): 376-379 .  
Abstract   PDF(pc) (190KB) ( 479 )
The transformation horn stage-2 to stage-1 in HC1O4-graphite intercalation compounds is studied by in-situ Raman scattering. The results show the coexistence of well-ordered regions of both stages during the stage transition. The resonant enhancement of Raman scattering has been found in stage1 and stage-2 HC1O4-GICs.
Mapping the Uniformity of Deep Level Defects Distribution by Scanning Photoluminescence
WENG Yumin, LIN Song, ZONG Xiangfu
Chin. Phys. Lett. 1991, 8 (7): 380-383 .  
Abstract   PDF(pc) (208KB) ( 546 )
Deep level defects in undoped semi-insulating GaAs were investigated by photo-luminescence technique at room temperature. The 0.69eV band is associated with the main mid-gap level EL2, and the 0.76eV band is suggested to be caused by some native point defects related to excess As, such as As anti-site defect. Two-dimensional and pseudo three-dimensional plots of the EL2 related band have been observed for as grown and annealed wafers.
14 articles