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Volume 8 Issue 4
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Original Articles
Rapidity Distributions in Proton-Proton Collisions at 40 TeV
WANG Zhengzhi
Chin. Phys. Lett. 1991, 8 (4): 165-167 .  
Abstract   PDF(pc) (100KB) ( 454 )
The derivative of natural logarithms of the average number of negative charged mesons with respect to the rapidity and the multiplicity moments were calculated, assuming that P(n, k) is probability and P(n, 1 ) is negative binomial distribution under condition of l < k < l + 1.

Evaluation of the Witten Index in 1+1 Dimensional Supersymmetric Models with O(N) Symmetry
YU Yangzheng, LIN Tingting
Chin. Phys. Lett. 1991, 8 (4): 168-171 .  
Abstract   PDF(pc) (141KB) ( 447 )
We present a way to calculate the Witten index Δ for a class of l+l dimensional supersymmetric (SUSY) models with O(N) symmetry. Since Δ is invariant under an adiabatic change of parameters, an O(N) non-invariant but SUSY term 2hФN is added to the Lagrangian, therefore the degeneracy of zero-energy states due to O(N) symmetry is removed. It is shown that SUSY breaking can occur for the SUSY O(N) Wess-Zumino model.
Hyperfine Structure Measurements of 235U High-Lying Levels Using a Hollow-Cathode Lamp
JIA Liejuan, JING Chunyang, LIN Fucheng
Chin. Phys. Lett. 1991, 8 (4): 172-175 .  
Abstract   PDF(pc) (163KB) ( 476 )
The hyperfine structure (hfs) of three 235U high-lying levels has been measured by using a hollow-cathode lamp and laser-induced fluorescence technique. These transitions are from the first excited states at 16900 and 16505cm-1 to the higher exited states. From the measured spectra, the isotope shifts and hfs widths for these levels are determined, and the hfs constants A and B for two levels are obtained.
Generation of Violet and Blue Diffuse-Bands of Stimulated Radiation in Lithium Dimer
LI yongfang, SHEN Jiangi, JIN Haiyan, QIN Lijuan, FU Kede, WANG Zugeng
Chin. Phys. Lett. 1991, 8 (4): 176-179 .  
Abstract   PDF(pc) (206KB) ( 444 )
Blue (455.0-465.0 nm) and violet (407.0-418.0 nm) diffuse-bands of stimulated radiation are generated via two-photon excitation of lithium dimer by pumping laser tuned to any wavelength in the region of 620.0-660.0nm and via two-photon resonant excitation of atomic Li, respectively. The mechanisms involved are discussed.

Second Harmonic Generation in a KNbO3 Slab Waveguide
WU Lusheng, P.GUNTER*
Chin. Phys. Lett. 1991, 8 (4): 180-183 .  
Abstract   PDF(pc) (190KB) ( 406 )
An experiment of second harmonic generation in a KNbO3 slab waveguide u reported. A power conversion efficiency of 11.3% and a slope efficiency of 17% have been obtained in a 93μm waveguide pumped by a Q-switched Nd:YAG laser. The oscillation output with increase of the beam diameter is due to the interference effect in waveguide.

Real-Time Edge Enhancement Using KNSBN at 633 nm
WU Xiaoguang*, SHAO Zongshu, CHEN Huanchu, SONG Yongyuan, SUN Daliang
Chin. Phys. Lett. 1991, 8 (4): 184-186 .  
Abstract   PDF(pc) (158KB) ( 490 )
Edge enhancement has been performed in Ce-doped (K0.5Na0.5)2y (Sr0.61 Ba0.39)1-yNb2 O6(KNSBN) crystal at 633nm with low incident-light intensities 10-3W/cm2). We calculated the expected images which show good agreement with the images that we have experimentally observed.

Investigation of Optical Properties of Amorphous Gap Films
XU Jianhong, CHEN Kunji, ZHU Enjun*
Chin. Phys. Lett. 1991, 8 (4): 187-190 .  
Abstract   PDF(pc) (193KB) ( 423 )
The optical properties of amorphous Gap (a-Gap) films prepared by plasma enhanced transport deposition method in the system of Ga-PCl3-H2 have been studied. The optical energy band gap Eoptg of a-Gap films is about 1.6 e V which depends on the contents of Cl atoms. The results of exponential absorption edge indicate that there is a high density of band-tail states in the optical energy band gap.
Growth of α-LiIO3 Single Crystal Grown in Space
MAI Zhenhong, CHEN Wanchun, CUI Shufan, MA Wenyi, XIE Anyun, XU Lu, JIN Zecen, CHEN Gang
Chin. Phys. Lett. 1991, 8 (4): 191-194 .  
Abstract   PDF(pc) (176KB) ( 408 )
α-LiIO3 single crystals were grown by the aqueous solution method in a Chinese scientific return-satellite. The morphology of the crystals grown in space are similar to that of earth-grown crystals. It is found that the growth rates of the positive and negative sides of the space-grown crystals are almost the same. The perfection of both crystals grown in space and on earth was examined.
Elastic Constants and Phonon Dispersion Curves of Tetragonal La2CuO4 Single Crystal
MU Yaoming, TAO Ruibao*
Chin. Phys. Lett. 1991, 8 (4): 195-198 .  
Abstract   PDF(pc) (159KB) ( 498 )
The elastic constants and phonon dispersion curves of tetragonal La2CuO4 single crystal are calculated with rigid-ion model. We obtain rather good agreement between the computed and measured elastic constants. The calculated phonon dispersion curves exhibit a rather conventional behavior except the anomaly of a Σ4, symmetry TO mode at Γ-X direction.


Adsorption of CH3OD on Si(ll1) Surface at Different Temperatures
WANG Zhuying, HUANG Hongwu, T. Hein*, K. D. Brzoska*
Chin. Phys. Lett. 1991, 8 (4): 199-202 .  
Abstract   PDF(pc) (227KB) ( 494 )
Adsorption of deuterated methanol (CH3 OD) on Si ( 111 ) surface has been studied at different temperatures by means of thermal desorption spectroscopy. For the adsorption temperature below 420°C, the desorption peak of hydrogen kept up almost unchanged at 510°C (±70°C). But the desorption peak temperature of hydrogen increased obviously for the adsorption temperature above 420°C. We have also found an interesting change in desorption energy of hydrogen.
Preparation of High Quality p-Type Diamond Thin Films by Thermal Chemical Vapor Deposition
YU San, JIN Zengsun, LÜ, Xianyi, ZOU Guangtian
Chin. Phys. Lett. 1991, 8 (4): 203-206 .  
Abstract   PDF(pc) (218KB) ( 390 )
P-type semiconducting polycrystalline diamond thin films doped with boron were synthesized on single crystalline silicon substrate by thermal chemical vapor deposition from a tungsten filament and placing boron-contained substance (boron nitride or elemental boron) on sample holder. The films were determined to be the high quality diamond by Raman spectroscopy, X-ray diffraction and scanning electron microscope measurements. The doping properties of boron were measured by Hall method and infrared absorption.
First Principle Calculations of Quasiparticle Energies for Band Structures of Si and GaAs
WANG Jianqing, GU Zongquan, WANG Bingxin, LI Mingfu,
Chin. Phys. Lett. 1991, 8 (4): 207-210 .  
Abstract   PDF(pc) (219KB) ( 685 )
We have applied the Green function theory in GW approximation to calculate the quasiparticle energies for semiconductors Si and GaAs. Good agreements of the calculated excitation energies and fundamental energy gaps with the experimental band structures were achieved. We obtained the calculated fundamental gaps of Si and GaAs to be 1.22 and 1.42eV in comparison to the experimental values of 1.17 and 1.52e V, respectively. Ab initio pseudopotential method has been used to generate basis wavefunctions and charge densities for calculating dielectric matrix elements and electron self-energies.
Temperature Stability of Vertical Bloch Line Chains in the Walls of the First Kind of Dumbbell Domains
JI Ping, LIU Dapeng, NIU Xiude, HAN Baoshan
Chin. Phys. Lett. 1991, 8 (4): 211-214 .  
Abstract   PDF(pc) (188KB) ( 375 )
The “softening” process of the first kind of dumbbell domains (IDs) with the increase of temperature was experimentally revealed as follows: IDs first convert to ordinary hard bubbles (OHBs) through a partial loss of the vertical Bloch lines (VBLs) in their walls and then these OHBs convert to soft (normal) bubbles (SBs) through a further loss of VBLs. As a result, the critical temperature for the break down of VBL chains of IDs is apparently higher than OHBs.
0.5981μm Sum Frequency Mixing in KTP Crystal
SHEN Hongyuan, ZHOU Yuping, LIN Wenxiong, ZENG Ruirong, YU Guifang, HUANG Chenghui, ZENG Zhengdong, ZHANG Weijia, JIA Shouquan*, JIANG Peizhi*, XIAO Chaoliang*
Chin. Phys. Lett. 1991, 8 (4): 215-217 .  
Abstract   PDF(pc) (125KB) ( 423 )
Based on accurate values of refractive indices, the phase matching angles (θm) and effective nonlinear coeficients (deff) for type I and I I sum frequency mixing of 1.0795 and 1.3414μm radiations were calculated in KTP crystal. The optimum phase matching conditions are that θm =75.74o in the XZ plane (Ф=0) and deff = 17. 42 x 10-9 esu. The calculated results agree well with the experimental results. Thus, the cw 0.5981μm sum frequency radiation was achieved in KTP crystal using a 1.0795 and 1.3414μm double-wavelength Nd:YAP cw laser.
14 articles