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Volume 11 Issue 5
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Original Articles
Electromagnetic Scattering from One-Dimension Fractal Surface
GUO Lixin, WU Zhensen
Chin. Phys. Lett. 1994, 11 (5): 257-260 .  
Abstract   PDF(pc) (209KB) ( 510 )
In this paper, the surfaces are modeled by multiscaled band-limited continuous fractal function and fractional Brownian motion function. The relationship between the scattering behavior and geometrical characteristics of the fractal surface is analysed in detail based on the perturbation solution and Kirchhoff approximation. Finally, some discussions are given about scattering from fractal surface.
Possible vT Mass Measurement Study at Beijing Spectrometer
CHEN Shaomin, YAN Wuguang, LI Jin, ZHENG Zipeng
Chin. Phys. Lett. 1994, 11 (5): 261-264 .  
Abstract   PDF(pc) (205KB) ( 325 )
This paper investigates the feasibility of the T neutrino mass measurement at the Beijing Spectrometer (BES). The T event selection criteria have been obtained by studying the earlier BES Ds data. Based on a total integrated luminosity of 35pb-1 at √s = 4.03 GeV, an upper limit on mvT, of approximately 25 MeV appears possible for the T →K+K-πvT, decay channel.
Interaction Between Two Nonlinear Schrödinger Solitons
ZOU Fengwu, YAN Jiaren*
Chin. Phys. Lett. 1994, 11 (5): 265-268 .  
Abstract   PDF(pc) (180KB) ( 429 )
The interaction between nonlinear Schrödinger solitons is derived by the least action principle approach as a potential function of the soliton's separation and their initial relative phase, which shows clearly how the solitons interact with each other. Two solitons with the same initial phase always attract each other, while those of opposite phase repel. The method developed in this paper can be extended to deal with interaction between solitons of other nonlinear equations.
Transient-State and Steady-State Light-Induced Scattering in Photorefractive Crystal LiNbO3 : Fe
LIU Junmin, LIU Simin, XU Jingjun, ZHANG Guangyin, XIONG Guisheng, MEN Liqiu, GUO Ru
Chin. Phys. Lett. 1994, 11 (5): 269-272 .  
Abstract   PDF(pc) (244KB) ( 356 )
We found that drift-length of light-excited electrons L0 has influence upon the light-induced scattering in LiNbO3 :Fe crystal. We proposed that one of the necessary conditions for steady-state light-induced scattering is D > L0 (where D is the illumination beam size).
Study of the Retracing Behavior of the Phase-Matching Angle in Second Harmonic Generation
LIU Xiang, DENG Daoqun, WU Ling-an, XU Zuyan, CHEN Chuangtian, WU Baichang
Chin. Phys. Lett. 1994, 11 (5): 273-276 .  
Abstract   PDF(pc) (166KB) ( 660 )
The retracing behavior of the phase-matching angle (RBPA) in many nonlinear optical crystals for second harmonic generation (SHG) has been demonstrated by calculation. The generality of this phenomenon is successfully explained by a theoretical analysis based on classical optics. The wavelengths of the fundamental waves and phasematching angles for describing the RBPA of eight kinds of crystals are presented. Furthermore, we point out that RBPA exists generally in both uniaxial and biaxial crystals for both type I and type II SHG.
Experimental Study on the Properties of Line-Shaped Laser-Plasma
HAN Shensheng, ZHANG Lingqing, XU Zhizhan, ZHANG Zhengquan, SUN Lan
Chin. Phys. Lett. 1994, 11 (5): 277-280 .  
Abstract   PDF(pc) (208KB) ( 433 )
Line-focused high power laser was used to irradiate a magnesium slab target in order to generate line-shaped laser-plasma. Plasma parameter profile distribution (electron temperature and electron density) on the direction perpendicular to the target surface was obtained by spectroscopic diagnostic method, which is quite different from that of the spot-shaped laser-plasmas. New experimental phenomena that can be interpreted as “plasma satellites” were also observed.
Lattice Dynamics of β-Si3N4
CHEN Luwei, CHEN Chuanhong
Chin. Phys. Lett. 1994, 11 (5): 281-284 .  
Abstract   PDF(pc) (160KB) ( 676 )
Valence force field model has been constructed for lattice dynamics of β-Si3N4. The values of force constants were determined by fitting the phonon frequencies of r point to experimentally observed Raman spectra. The phonon dispersion curves in several principal directions in Brillouin zone, the total density of states and some phonon related physical properties were calculated.
Thermal Stability of Magnetron Sputtered Low Hydrogen Content Diamondlike Carbon
CHENG Degang, LÜ, Fanxiu, SUN Qinbiao, YU Wenxiu, YANG Rang
Chin. Phys. Lett. 1994, 11 (5): 285-288 .  
Abstract   PDF(pc) (197KB) ( 437 )
Response to vacuum annealing at temperatures up to 600°C for 3h for low hydrogen content diamondlike carbon (LHDLC) films prepared by magnetron sputtering of pure graphite in pure Ar atmosphere has been studied. Optical properties of the as-deposited and annealed films have been characterized by ellipsometry and infrared spectroscopy. No change was found for the films annealed at up to 400°C. The LHDLC begins losing hydrogen after annealing above 400°C and the sp2 hybrid structure increases. The refractive index of the films increases with increasing annealing temperatures above 500°C. Annealing at 600°C results in graphitization and the loss of IR transparency.
Photoconductivity Characteristics of Porous Silicon
LIU Kaifeng, WENG Yumin, ZHU Lei*, WANG Shenyi*, ZONG Xiangfu
Chin. Phys. Lett. 1994, 11 (5): 289-292 .  
Abstract   PDF(pc) (232KB) ( 678 )
The highly photo-sensitive characteristics of porous silicon (PS) were observed. The transient behaviors of photoconductivity in horizontal and perpendicular directions of PS surface were very different, though both of them include two decay components. The photoconduction spectra at room temperature and 14.5K show that characteristics of PS are different from those of silicon substrate. The difference may be attributed to quantum confinement effect in nano-size microstructures of PS.
Channeling Alignment for Epitaxial Light-Mass Film on Heavy-Mass Substrate
YIN Shiduan, XIAO Guangming, ZHU Peiran*
Chin. Phys. Lett. 1994, 11 (5): 293-296 .  
Abstract   PDF(pc) (157KB) ( 383 )
A simple procedure for obtaining a background-free backscattering spectrum of a light-mass film on a heavy-mass substrate by a normal incidence/grazing exit geometry has been described. Using this method such films can be aligned rapidly and accurately, and the impurity or defect information on the films can be obtained without need for realignment. Example is given from MeV 3Li+ analysis of a deposited film of Si on a single crystal substrate of yttria-stabilized, cubic zirconia.
Electrical Properties of Periodic Pd/Mo Bimetal Films
WANG Xiaoping, ZHAO Texiu, WANG Shunxi*, JI Hang, LIANG Qi
Chin. Phys. Lett. 1994, 11 (5): 297-300 .  
Abstract   PDF(pc) (206KB) ( 441 )
The electrical resistivity and the temperature coefficient of resistance (TCR) of periodic Pd/Mo bimetal films are reported for the bilayer wavelength in the range 1.5-13nm by varying the ratio of Pd and Mo thicknesses in the temperature range from 77 to 300K. The resistivity is found to be nearly proportional to the inverse of the bilayer wavelength. The most striking feature is that the TCR is decreased with bilayer wavelength and the change in sign of the TCR as Pd/Mo thickness ratio is varied. Taking into account the effects of electron weak localization in Mo layer, the experimental results can be explained.
YBa2Cu3O7-x Superconducting Thin Films Grown on CaNdA1O4(100) Substrates
XU Shifa, ZHOU Yueliang, LÜ, Huibin, CUI Dafu, CHEN Zhenghao, YANG Guozhen, TIAN Yongjun*, LIU Junzheng*, LI Lin*, CHANG Yingchuan, HOU Desen, FAN Hui, ZHANG Zuren
Chin. Phys. Lett. 1994, 11 (5): 301-303 .  
Abstract   PDF(pc) (136KB) ( 452 )
We report the fabrication of high temperature superconducting YBa2Cu3O7-x thin films on CaNdA1O4(100) substrate by pulsed laser deposition. Films have excellent features. X-ray diffraction patterns show that thin films are epitaxial with c-axis orientation normal to the surface of su bstrate. The four-terminal measurements indicate the zero resistance temperature of 92.1 K, and transition width of 0.7K, the critical current density of 3 x 106 A/cm2 at 77K and under zero magnetic field.
Synthesis of High Temperature Superconductors HgBa2CuO4+y and HgBa2Ca2Cu3O8+y
YAO Yushu, SU Yanjing*, JIA Shunlian, CAO Guohui*, WU Fei, ZHAO Zhongxian
Chin. Phys. Lett. 1994, 11 (5): 304-306 .  
Abstract   PDF(pc) (137KB) ( 462 )
High critical temperature superconductors of mercury- based system were synthesized under high pressure and high temperature. The resistance and ac magnetic susceptibility measurements for sample prepared at 25 kbar and 850°C for 1.5 h show that the sample without any added treatment was a mixture of Hg-1201 and Hg-1223. The Tc values of Hg-1223 phase and Hg-1201 phase are 132 and 98 K, respectively.
Specific Heat of Quantum Heisenberg Spin Glasses: Magnetic Field Effects
XIONG Yuansheng, YI Lin, YAO Kailun, LI Zaiguang
Chin. Phys. Lett. 1994, 11 (5): 307-309 .  
Abstract   PDF(pc) (139KB) ( 481 )
The quantum spin glass theory with the infinite-range random Dzyaloshinskii-Moriya interaction presented by Yi and his cooperators is investigated numerically at a fixed anisotropy interaction for different external magnetic fields and spin number 1/2. Specifically, the dependences of the typical specific heat and entropy of spin glass on temperatures have been obtained theoretically.
Barium Titanate Prepared by Stearic Acid-Gel Method
REN Tianling, ZHANG Peilin, WANG Yuguo, ZHONG Weilie, WANG Xiaohui*, XU Baokun*
Chin. Phys. Lett. 1994, 11 (5): 310-313 .  
Abstract   PDF(pc) (189KB) ( 643 )
Stearic acid-gel method was used to prepare barium titanate. All the samples show a cubic perovskite structure and thus no ferroelectricity is detected at room temperature. X-ray diffraction reveals that the grains can hardly grow even firing at high temperature so that the grain size in most of the samples is below the ferroelectric critical size. A tentative explanation is proposed of the peculiarities based on the nonstoichiometry at the surface layer.

Refractive Index and Extinction Coefficient of Hg1-xCdxTe at 77 and 300K
JIANG Runqing, ZHANG Shuzhi, WU Feifei, HU Xierong, FANG Jiaxiong, SHEN Jie, XU Guosen
Chin. Phys. Lett. 1994, 11 (5): 314-316 .  
Abstract   PDF(pc) (115KB) ( 559 )
We measured refractive index and extinction coefficient of n type Hg1-xCdxTe with the null ellipsometric spectrum method over the visible light region at 77 and 300K, and the dispersion relation at different temperature is discussed. The value of refractive index at 77K is smaller than that at 300K, and the changes of the extinction coefficient curve at 77K is also smaller than that at 300K.
Direct Deposition of Polycrystalline Diamond Films on the Si( 100) Mirror Surface by Hot Filament Chemical Vapor Deposition
GAO Chunxiao, ZOU Guangtian, JIN Zengsun
Chin. Phys. Lett. 1994, 11 (5): 317-320 .  
Abstract   PDF(pc) (268KB) ( 545 )
High quality diamond films have been deposited on Si(100) mirror surface without using any surface pretreatment such as abrasive diamond scratching, diamond-like carbon predeposition or oil treatment. The experiments are carried out in the hot filament chemical vapour deposition system by using the mixture of methane, hydrogen and oxygen. The films show the well-defined facets and are confirmed by Raman spectroscopy and scanning electron microscopy to be high quality diamond films. In this deposition process, higher substrate temperature, high filament temperature and oxygen addition play the important roles in diamond nucleation on the mirror-smooth Si(100) surface.
17 articles