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Volume 5 Issue 7
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Original Articles
COMPETITION BETWEEN STIMULATED RAMAN SCATTERING AND RESONANT LASER EMISSION
CHENG Bingying, ZHANG Jie, ZHANG Daozhong, ZHAO Lizeng, ZHAO Yuyinq, WANG Tianjuan
Chin. Phys. Lett. 1988, 5 (7): 289-292 .  
Abstract   PDF(pc) (46KB) ( 390 )
Competitive phenomena between stimulated Raman scattering and resonant laser emission In atomic lead are studied through photodissociation of PbCI2 with a UV laser. The different dependences of their intensities on the UV power, the density of PbC12 and the pressure of buffer gases are investigated. The results indicate that under the conditions of high pump intensity and low buffer gas pressure SRS can have the advantage of RLE.
STRUCTURAL TRANSITIONS IN 90K SUPERCONDUCTING PEROVSKITE Ba2LaCu307-y:A TEM STUDY
GU Hui, LI Qi, ZHANG Jinlong, ZOU Bensan*, YIN Daole
Chin. Phys. Lett. 1988, 5 (7): 293-296 .  
Abstract   PDF(pc) (58KB) ( 417 )
An orthorhombic-to-tetragonal structural transition of high Tc Ba2LaCu307-y samples was observed with transmission electron microscope( TEM). Two intermediate orthorhombic structures were discovered and discussed. Thus, the Ba2LaCu307-y is another member of high Tc Ba2LnCu307-y (Ln=Lathanides) family with lower structural transition temperature.
NUCLEON-NUCLEON INTERACTION WITH A FLAT BOTTOM LINEAR CONFINEMENT POTENTIAL IN THE QUARK MODEL
DING Xiaonan, SHEN Pengnian, ZHANG Zongye, YU Youwen
Chin. Phys. Lett. 1988, 5 (7): 297-300 .  
Abstract   PDF(pc) (50KB) ( 383 )
Nucleon-nucleon interaction is studied in the non-relativistic quark model with a flat bottom linear confinement potential. The results are consistent with the calculated ones from the lattice quantum chromodynamics. The quark-quark interaction also consists of those caused by the one gluon exchange and the one pion exchange. The phenomenological sigma meson exchange between two nucleons is also included to fit the S-wave N-N scattering data. The calculated NN channel S-wave phase shifts show that the flat bottom linear confinement potential can provide part of the medium range attraction.
SUPERCONDUCTIVITY OF LaBa2-xCaxCu3Oy SYSTEM
WEI Chongde, LIN Chin, ZHOU Yaqin, WU Ke, Xue Lixin
Chin. Phys. Lett. 1988, 5 (7): 301-304 .  
Abstract   PDF(pc) (38KB) ( 353 )
The high Tc superconductor LaBa2-xCaxCu3Oy has been studied and the composition dependence of Tc examined For x=1, Tconset = 94K,TcR=0 =80K. The structure of this system was refined utilizing the X-ray powder diffraction data, and it was found that the material is isostructural with YBa2Cu3Oy.
NON-PROPAGATING SOLITARY WAVE ON SURFACE OF FLUID WITH SMALL VISCIDITY EXCITED BY EXTERNAL DRIVE
YAN Jiaren, HUANG Guoxiang
Chin. Phys. Lett. 1988, 5 (7): 305-308 .  
Abstract   PDF(pc) (44KB) ( 592 )
The expression of non-propagating solitary wave on surface of fluid with small viscidity excited by external drive has been obtained uing the method of multiple scales. Some discussions have been made on the result obtained, which is consistent with that of Larraza and Putterman with the external drive and viscidity being neglected.
EXCLUSIVE MEASUREMENT OF A QUARTERNARY FRAGMENTATION EVENT OF RELATIVISTIC OXYGEN NUCLEUS IN EMULSION
TANG Xiaowei, SUN Shurong, ZHENG Puying
Chin. Phys. Lett. 1988, 5 (7): 309-312 .  
Abstract   PDF(pc) (43KB) ( 385 )
An event of peripheral collision of a relativistic oxygen nucleus. which immediately disintegrates into four helium nuclei, a quarternary fragmentation event, has been measured exclusively, and the mechanism of this event is discussed. The quarternary fragmentation phenomenon may provide an experimental evidence for the cluster model of oxygen nucleus.

MOLECULAR DYNAMICS STUDY ON α IRON GRAIN BOUNDARY STRUCTURE AT DIFFERENT TEMPERATURES
CHEN Zhiying, DING Jiaqiang, ZHOU Fuxin, TANG Cangya, YE Zhou, WU Xijun*
Chin. Phys. Lett. 1988, 5 (7): 313-316 .  
Abstract   PDF(pc) (49KB) ( 467 )
The Σ=9 grain boundary (GB) structures of α iron at different temperatures were simulated with a molecular dynamical method. Johnson's potential was used and constant volume assumption was made. The maximum number of atoms was 1376. Temperature effects on the relaxed GB structures at 600K and at 900K were detected, while the difference between structures at OK and at 300K was negligible. Some techniques for speeding up the computing process were developed and the criterion of equiliblium was discussed.
TEMPORAL EVLOUTION OF THE STARK-BROADENING OF Hβ LINE IN LASER-INDUCED PLASMA IN METHANE
XING Xing, WANG Lixin, HUANG Nantang, XU Jiren
Chin. Phys. Lett. 1988, 5 (7): 317-320 .  
Abstract   PDF(pc) (43KB) ( 394 )
The temporal evolution of stark-broadening of Hβ line in laser-induced plasma in methane is investigated and the electronic density is determined from the Stark-broadened linewidth of the Balmer beta line. The maximum half-width of the line is more than 100Å and the deduced electronic density is about 4x1017cm-3.

OBSERVATIONS OF PERCOLATION STRUCTURES INDUCED IN THIN SOLID FILMS BY ION IRRADIATION
DING Juren*, HUANG Liji*, LIU Baixin
Chin. Phys. Lett. 1988, 5 (7): 321-324 .  
Abstract   PDF(pc) (65KB) ( 388 )
Percolation structures of precipitated new phases were observed in Au-Ti and Ni-A1 amorphous films upon ion irradiation. The experimental evidences showed that the observed structures were formed in the surface layer, ca 20nm thick. It was revealed that the formation of percolation clusters was sensitive to alloy composition as well as irradiation dose.
A METHOD OF ROTABLE SOURCE MASS TO TEST THE GRAVITATIONAL INVERSE SQUARE LAW
ZHANG Pinghua
Chin. Phys. Lett. 1988, 5 (7): 325-328 .  
Abstract   PDF(pc) (48KB) ( 350 )
Our experiment make the zeroing of the torsion balance easier at small distance. and the non-Newtonian force of α=0.01, λ=0.25cm can be detected.
A SERS STUDY OF 1.2.3-BENZOTRIAZOLE ADSORBED ON SILVER SURFACE
ZHANG Pengxiang, LIANG Erjun*, LI Xiuying
Chin. Phys. Lett. 1988, 5 (7): 329-332 .  
Abstract   PDF(pc) (43KB) ( 479 )
The structure of N-heterocyclic complex formed by benzotriazole on silver colloidal surface is determined with SERS technique. It is found that the adsorption on silver surface is through the triazole part of the molecule. A new chemical reaction in this system is found with the SERS technique.

THE INFLUENCE OF FLUID FLOW ON DENDRITE TIP IN BRIDGMAN GROWTH
HUANG Tao, ZHOU Yaohe
Chin. Phys. Lett. 1988, 5 (7): 333-335 .  
Abstract   PDF(pc) (50KB) ( 382 )
The influence of fluid flow on the dendritic growing tips in region close to the growth interface have been studied quantitatively. The effect of asymmetrical parabola tips and the crossover of diffusion-convection transport mechanisms on crystal growth behaviour have been found for the first time.
12 articles