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Volume 12 Issue 9
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Original Articles
New Finite-Dimensional Integrable Systems by Binary Nonlinearization of WKI Equations
XU Xixiang
Chin. Phys. Lett. 1995, 12 (9): 513-516 .  
Abstract   PDF(pc) (0KB) ( 307 )
A symmetry constraint for Wadati-Konno-Ichikawa (WKI) equations is presented by binary nonlinearization. The spatial part and the temporal parts of Lax pairs and the adjointt Lax pairs of WKI equations are all constrainted as finite dimensional Liouville integrable Hamiltonian systems, whose integrals of motion are explicitly given.
Compatibility Between the Spin Experiments and the Improved Ellis-Jaffe Sum Rules
LIU Jueping
Chin. Phys. Lett. 1995, 12 (9): 517-520 .  
Abstract   PDF(pc) (194KB) ( 410 )
A compatibility between the proton, neutron and deuteron spin experimental data, based on a combined analysis from all available informations, and the improved Ellis-Jaffe sum rules are verified. The spin structure of proton in a ground state is analysed, and the gluon contribution is proven to be very important.
Triton-Triton Correlation and Emission Times in Intermediate Energy Nucleus-Nucleus Collisions
HE Zhiyong, DUAN Limin, LI Zuyu, JIN Genming, LUO Qingzheng, WU Heyu, ZHANG Baoguo, WEN Wanxin, QI Yujin, DANG Binrong, DAI Guangxi
Chin. Phys. Lett. 1995, 12 (9): 521-523 .  
Abstract   PDF(pc) (174KB) ( 461 )
Triton-triton correlation functions have been measured for 40Ar+197Au collisions at E/A = 25 MeV. The anticorrelations at small relative momenta are observed and become more pronounced with the increasing total energy of two coincident tritons. Comparison with the three-body trajectory calculations indicates that the average emission times lie between 100 and 300fm/c for tritons.
Cu K X-ray Emission by MeV Cluster Beam Bombardment
XIA Zonghuang, WANG Qian, SHEN Dingyu, LI Shuozhong
Chin. Phys. Lett. 1995, 12 (9): 524-526 .  
Abstract   PDF(pc) (150KB) ( 511 )
The MeV cluster beam of (C)+2 ions has been bombarded on a copper target and K x-ray spectra of Cu have been measured with a Si(Li) detector. It is found that the K x-ray spectra of Cu induced by bombardment with 2.8 MeV (C)+2 and 1.4 MeV C+ ions are almost the same. In contrast, K x-ray spectra of Cu induced by bombardment with 2.8 MeV (C)+2 and 3.0 MeVSi+ ions are quite different. These interesting phenomena are discussed.

New Model of Potential Energy Functions for Atomic Solids and Application to Silicon Crystal
LIU Xinhou
Chin. Phys. Lett. 1995, 12 (9): 527-529 .  
Abstract   PDF(pc) (156KB) ( 495 )
A new theoretical model of potential energy functions for atomic solids is developed. An angular factor is included in this model and its effect is discussed. Using this new model, a new preliminary potential for silicon crystal is derived. Calculated phonon dispersion curves, using this new potential, is given. A good agreement has been found.
Theoretical Calculation of Dielectronic-Recombination Cross Section for Hydrogen-Like Argon
WANG Jianguo, ZOU Yu, DONG Chenzhong*, LI Jiaming
Chin. Phys. Lett. 1995, 12 (9): 530-532 .  
Abstract   PDF(pc) (145KB) ( 581 )
Dielectronic-recombination cross sections of hydrogen-like argon are calculated conveniently by our simplified relativistic configuration-interaction method. The results for the KLL, KLM, KLN, and KLO resonances are in good agreement with experimental measurement within a few percent. Our methods can provide various dielectronic-recombination rates which can satisfy the need for relevant applications.
Coherent Mutually Pumped Phase Conjugation Induced with High-Efficiency by Self-Pumped Phase Conjugate Reflection
SUN Xiudong, ZHANG Jingwen, ZHOU Zhongxiang, XU Kebin, HONG Jing, JIANG Quanzhong, CHEN Huanchu, ZHU Guizhi
Chin. Phys. Lett. 1995, 12 (9): 533-536 .  
Abstract   PDF(pc) (259KB) ( 445 )
A new scheme of coherent mutually pumped phase conjugate (MPPC) reflection that depends on the formation of self-pumped phase conjugate reflection of another beam has been demonstrated in a Cu:KNSBN crystal. The dependences of the MPPC reflectivity on the intensity ratio of the two incident beams and on the incident position of the signal beam were measured. We obtain phase conjugate reflectivities of greater than 90% at 488nm.

Temporal Behaviours of Stimulated Rayleigh-Wing Scattering at Non- and Quasi-Equilibrium of Orientational Distribution
WANG Hezhou, ZHENG Xiguang, MAO Weidong, YU Zhenxin, GAO Zhaolan
Chin. Phys. Lett. 1995, 12 (9): 537-540 .  
Abstract   PDF(pc) (193KB) ( 397 )
The temporal behaviours of stimulated Rayleigh-wing scattering, at quasi-equilibrium and non-equilibrium of the molecular orientational distributions, are reported in this letter. The experimental results also show the relaxation time of molecular orientation in high alignment is longer than 80 picosecond.
Propagation of Optical Pulses in a Deviated Gaussian Gained Kerr Medium
SUN Xun, CHEN Yisheng, XU Lang
Chin. Phys. Lett. 1995, 12 (9): 541-544 .  
Abstract   PDF(pc) (225KB) ( 418 )
This paper presents the theoretical studies on the propagation of optical pulses in a deviated Gaussian gained Kerr medium. Our numerical results have shown, for the first time, that the compression of optical pulse widths varies considerably for differently deviated Gaussian gain.

Effects of Group-Velocity Dispersion on the Self-Trapped Optical Pulses in a Planar Waveguide
LIU Shanliang, WANG Wenzheng, XU Jingzhi
Chin. Phys. Lett. 1995, 12 (9): 545-548 .  
Abstract   PDF(pc) (193KB) ( 429 )
We give the exact bright solitary wave solutions of (2+1)-dimensional nonlinear Schrödinger equation and analyze the effects of group-velocity dispersion (GVD) on the self-trapped pulses in a planar waveguide. The results show that the self-trapped pulses are unstable and collapse at higher peak power in a planar waveguide with the anomalous GVD, but the collapse does not occur in a planar waveguide with the normal GVD; the peak power required for self-trapping of the pulse in a planar waveguide with the normal GVD is less than the critical peak power for collapse of the pulses in a planar waveguide with the anomalous GVD.
Anomalous Specific Heat Behavior of Nanocrystalline Fe at Low Temperatures
BAI Haiyang, LUO Jianlin, JIN Duo, SUN Jirong*
Chin. Phys. Lett. 1995, 12 (9): 549-552 .  
Abstract   PDF(pc) (208KB) ( 475 )
The specific heat of nanocrystalline iron with grain size of 40nm has been measured in the low temperature range from 1.8 to 26K. The anomalous specific heat behavior of nanocrystalline iron is compared to that of the standard bulk iron. It is found that the electronic specific heat coefficient γ obtained at low temperatures decreases by about 50%. A T2 term in the heat capacity associated with surface modes has been clearly observed. A large enhancement of the specific heat at temperatures above 16K may be interpreted as the Einstein oscillator contributions.

Determination of Hydrogen Activation Energy Spectrum in Amorphous Solids from Internal Frictions
XIE Qian, CHEN Nanxian
Chin. Phys. Lett. 1995, 12 (9): 553-556 .  
Abstract   PDF(pc) (184KB) ( 433 )
It is shown that the activation energy spectrum of hydrogen in amorphous materials can be determined from the temperature distribution of internal friction observed in anelastic relaxation measurements by using the deconvolution method of Fourier transform.
Observation of the Si(100)-(2 x 2) Phase and Measurements of Low Energy Electron Diffraction I-V Curves
HU Xiaoming, LIN Zhangda
Chin. Phys. Lett. 1995, 12 (9): 557-560 .  
Abstract   PDF(pc) (252KB) ( 526 )
A new phase of (2x2) has been observed as a result of hydrogen ion sputter etching on a clean reconstructed Si(100)-(2x1) surface using low energy electron diffraction (LEED). It has been found that the (2x1) surface first transformed into a metastable c( 4 x 4 ) phase following hydrogen ion etching and after further anneal of the sample, a (2x2) phase can be obtained. Intensity vs electron energy (I-V) curves for the
Si(100)-(2x2) pattern have been measured using a special video LEED system.

Magnetic Properties of Partial Melt (Tl0.5Pb0.5) (BaxSr0.8)2Ca2Cu3Oy(x = 0.1,0.2) Superconductors
QIN Mengjun, CAI Dianxian, JIN Xin, YAO Xixian, PENG Huotian, PENG Qiuyun, ZHOU Sihai
Chin. Phys. Lett. 1995, 12 (9): 561-564 .  
Abstract   PDF(pc) (198KB) ( 391 )
Magnetic measurements have been carried out on partial melt (Tl0.5Pb0.5)(BaxSr0.8)2Ca2Cu3Oy(x= 0.1,0.2) (TI-1223) samples, which indicate that higher melting temperature and longer melting time can be used to obtain Tl-1223 compound with better superconducting properties. On the contrary, introducing of Ba vacancy into Tl-1223 samples results in worse superconducting properties. At the end, the power law relationship between the critical current density and the applied field is explained by the flux creep model and the collective pinning theory.

Surface Modification of the Spontaneous Polarization in Ferroelectric Thin Films
QU Baodong, ZHONG Weilie, ZHANG Peilin
Chin. Phys. Lett. 1995, 12 (9): 565-568 .  
Abstract   PDF(pc) (201KB) ( 340 )
The surface effects on the spontaneous polarization in ferroelectric thin films were discussed based on the Ising model in a transverse field. Both the modifications of the transverse field and the strength of coupling in the surface layer were taken into consideration. At the temperature much lower than the Curie point, the behaviour of the spontaneous polarization deviates from the phenomenological description. The surface effects might lead to the spontaneous polarization and the Curie temperature changing in different direction. The theory gives a reasonable description of the experimental temperature dependence of the spontaneous polarization of triglycine sulfate thin films in the literature.
Enhancement of Organic Electrolum Inescent Intensity by Doping Hole-Property Polymers
WANG Guangming, WU Haiming, YUAN Chunwei, WEI Yu
Chin. Phys. Lett. 1995, 12 (9): 569-572 .  
Abstract   PDF(pc) (221KB) ( 467 )
Organic electroluminescent (EL) diodes with one-layer poly(3-octylthiophene) (P3OT) and P3OT doped with poly(N-vinylcarbazole) (PVK) (P3OT/PVK) as EL emitting layer sandwiched between indium/tin oxide (lTO) and aluminium electrodes have been fabricated by spin coating onto IT0 respectively. The P3OT/PVK EL diode starts to emit red-orange light at 5 V in our experiment, the luminance and the current for the P3OT/PVK EL diode at bias voltage was compared with those for the only P3OT EL diode, indicating that the PVK dopant has power over the P3OT electroluminescence.

Dielectric Polarization of Electrorheological Suspensions
HAO Tian, XU Yuanze, CHEN Yihong, XU Mao
Chin. Phys. Lett. 1995, 12 (9): 573-576 .  
Abstract   PDF(pc) (250KB) ( 614 )
The relation between electrorheological (ER) effect and dielectric properties of Polymer-based and inorganic-based suspensions were investigated. It is found that ER effect is determined not only by the dielectric constant of the suspended particles, but also by the dielectric loss, which provides a criterion whether suspension exhibits ER effect. The wagner model, which describes the interfacial polarization occurring in multiphase systems, was introduced to predict the dielectric behaviours of ER suspensions. A good agreement is found between experiments and theoretical predictions. The conductivity of the dispersed particles, the working temperature range and working frequency range of ER suspension can be optimized with Wagner model. The other ER phenomena such as the effect of water content were also explained by using this model.

17 articles