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Volume 9 Issue 1
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Original Articles
Accurate Monte-Carlo Tests of the Stochastic Ginzburg-Landau Model with Multiplicative Colored Noise
BAO Jingdong
Chin. Phys. Lett. 1992, 9 (1): 1-4 .  
Abstract   PDF(pc) (54KB) ( 455 )
An accurate and fast Monte-Carlo algorithm is proposed here for solving the Ginzburg-Landau equation with multiplicative colored noise. The stable cases of solution for choosing time steps and trajectory numbers are discussed.
Discussion of on the Translational Invariance the Gluon Condensate
BIAN Jianguo, HUANG Tao
Chin. Phys. Lett. 1992, 9 (1): 5-8 .  
Abstract   PDF(pc) (51KB) ( 557 )
In this article, the nonvanishing vacuum average value of two-point function of gluons <Ω|Aaμ(x)Abv(y)|Ω>, which is related to the quantitative analyses of the nonperturbative effects in quantum chromodynamics(QCD), is expanded in the space-time interval r=x-y in the Lorentz gauge. The first two coefficient values are estimated with the phenomenological values for the vacuum condensates <Ω|G2|Ω> and <Ω|ψψ|Ω> through the QCD motion equations. The advantage of the expansion is that the series remains translationally invariant as compared with the expansion of <Ω|Aaμ(x)Abv(y)|Ω> in the fixed-point gauge.
Constraints on Violation in the Fourth Generation Effect on CP Penguin-Dominated b → s Decays
XING Zhizhong, DU Dongsheng
Chin. Phys. Lett. 1992, 9 (1): 9-12 .  
Abstract   PDF(pc) (52KB) ( 498 )
The direct CP-violating asymmetries for the penguin-dominated b → sg, b → sγ, and b → sl+l- decays are reexamined using the generalized 4x 4 Kobayashi-Maskawa matrix proposed by Bjorken. We find that the fourth generation effect on these asymmetries are significantly constrained by the sign of sin Ф3/ sin Ф1, the imaginary part of the loop integral function for c-quark Im(Ic) , and the mass of t'-quark. Most of the previous predictions for this effect are too optimistic.
Dressing Multiphoton Hamiltonian
ZHOU Peng, PENG Jinsheng*
Chin. Phys. Lett. 1992, 9 (1): 13-16 .  
Abstract   PDF(pc) (50KB) ( 757 )
The dressed Hamiltonian describing the multiphoton process is presented by means of a canonical transformation. The exact eigenvalues and eigenstates are given for any set of parameters ω0, ω and ε . The general evolution of this system is obtained.
Generation of Diffuse Bands Stimulated Emission in 488~522 nm Region in Lithium Dimer
LI Yongfang, ZHANG Yinke, LI Fu an, LI Xiangsheng, FU Kede
Chin. Phys. Lett. 1992, 9 (1): 17-19 .  
Abstract   PDF(pc) (48KB) ( 507 )
We report diffuse bands stimulated emission of Li2 in the 488~522 nm region, produced by two-photon resonance excited Li (4s) states transferring energy to Li2 high triplet states via collision in Li- Li2 system. The diffuse bands could be assigned to triplet bound-free (23 Σ+g -a3Σ+u ) transitions. The mechanisms for producing and emission of the diffuse bands are discussed.

Pulsations in Optically Pumped Formic Acid 433 μm Far Infrared Laser
LUO Liguo, SU Jinwen, XIONG Shouren, CHEN Jishu
Chin. Phys. Lett. 1992, 9 (1): 20-22 .  
Abstract   PDF(pc) (50KB) ( 402 )
Pulsation behaviours of optically pumped Formic Acid (HCOOH) 433μm laser are observed. Pulsation frequency varies continuously with tilting the output cavity mirror or changing the HCOOH pressure. Unstable pulsations are observed at a relative high pressure or by changing a cavity mirror with higher output loss.

Photorefractive Self-Bending and High-Performance KNSBN:Cu Crystal Self-pumped Phase-Conjugator
ZHANG Guangyin, XU Jingjun, WU Yuanqing, LIU Simin, SUN Daliang*, SONG Yongyuan*, CHEN Huanchu*
Chin. Phys. Lett. 1992, 9 (1): 23-25 .  
Abstract   PDF(pc) (51KB) ( 518 )
The mechanism for the high-performance KNSBN:Cu crystal self-pumped phase-conjugator is first put forward in this letter as no-loop photorefractive self-bending succesive four-wave mixing interaction. And the photorefractive backscattering amplification was found to play a very important role in it.
Elastic Modulus Effect Related with Nonlinear Internal Friction
Chin. Phys. Lett. 1992, 9 (1): 26-29 .  
Abstract   PDF(pc) (65KB) ( 360 )
The behavior of elastic modulus related with strain amplitude is studied. It was found that modulus behaves softening when internal friction exhibits normal amplitude-dependent effects, while increases slightly with the appearance of anomalously amplitude-dependent effect. With the decrease of frequency of measurement, the variation of modulus with amplitude becomes small. A trial for obtaining information from amplitude internal friction peak was made on the basis of Debye equations.
Magnetic Properties in the Pseudoternary SmFeMnC Alloys
XING Feng, WANG Yingchun, SUN Ling, HE Wenwang
Chin. Phys. Lett. 1992, 9 (1): 30-32 .  
Abstract   PDF(pc) (59KB) ( 443 )
The intrinsic magnetic properties of the tetragonal Sm14 Fe78-x,MnxC8 , Ca sys tem are investigated. In addition to the sudden drop of σs, and Tc, an anomalous variation of the lattice constants is found. The sign of K1 changes from negative to positive between x=15 and 20 at 1.5K, thus the cone-type anisotropy becomes uniaxial correspondingly. The intrinsic magnetic hardness effect at low temperature is observed at high Mn content.
Charge Transport in Polyimide Electret During and After Corona Charging
XIA Zhongfu, JIANG Jian*, DING Hai
Chin. Phys. Lett. 1992, 9 (1): 33-36 .  
Abstract   PDF(pc) (68KB) ( 494 )
The influence of bulk conductivity at elevated temperature on injected charge depth along the thickness of polyimide foil was investigated by means of heat pulse technique and a three terminal-electrode system. The transport rule of detrapped real charge after corona charging and the main reason causing the decay of the charge in the bulk of the sample during thermally stimulated discharge were studied by measuring mean charge depths, steady-state conduction current-temperature curve and effective surface charge density.
Irreversibility Line and Critical Current
WEI Chongde, LIU Zunxiao, LAN Jan, GAN Zizhao, REN Hongtao*, HE Qing*, XIAO Ling*
Chin. Phys. Lett. 1992, 9 (1): 37-40 .  
Abstract   PDF(pc) (56KB) ( 673 )
The study of "irreversibility line" and magnetization curves of a YBCO superconductor prepared by melt-textured growth method is presented. It is shown that the temperature T* above which the magnetization is reversible can be identified with the temperature above which Jc is negligible, demonstrating the Yeshurun and Malozemoff s theory about "irreversibility line".

Volume Changes of Some Superconductive Oxides in Sintering Process
CHE Guangcan, SONG Chengyu, CHEN Xiaolong, LI Hua, XIONG Jiwu, ZHAO Zhongxian
Chin. Phys. Lett. 1992, 9 (1): 41-44 .  
Abstract   PDF(pc) (59KB) ( 467 )
The volume changes (ΔV) of YBCO, BSCCO and Y-substituted BSCCO superconductors in sintering process were measured and investigated. A comparison of volume change between these oxides indicates that the volume change is related with structural change and crystallizing dynamics.
Possible Spin-Liquid State in Doped Antiferromagnets
FENG Shiping, HAN Fei, GUO Rui
Chin. Phys. Lett. 1992, 9 (1): 45-48 .  
Abstract   PDF(pc) (54KB) ( 417 )
The phase diagram of the copper oxide materials as a function of doping δ is obtained in the framework of t-t - J- J model by using the Schiwinger boson-slave fermion theory. The results show that the both doped holes and quantum fluctuation of spins, which are treated on the same footing, are in favor of the spin-liquid state.

On the Order of the Phase transition in the Three-State Vector Potts Model on a Two-Dimensional Random Lattice
YING Heping, ZHANG Jianbo, JI Daren
Chin. Phys. Lett. 1992, 9 (1): 49-52 .  
Abstract   PDF(pc) (64KB) ( 421 )
We performed a Monte Carlo simulation of the three-state (Q =3) vector Potts model on a 2-D random lattice. It is shown that there is a peak in the specific heat but no thermal hysterisis of the energy that corresponds to a high-order phase transition (a second-order one). The result agrees with the analytical calculation and the qualitative picture obtained for the same model on the square lattice.
Band Gap Energy and Its Temperature Dependence of GaInAsSb Quaternary Alloy Grown by Molecular Beam Epitaxy
BI Wen gang, LI Aizhen
Chin. Phys. Lett. 1992, 9 (1): 53-56 .  
Abstract   PDF(pc) (65KB) ( 858 )
Room temperature band gap energies of MBE-grown Ga1-x InxAs1-y Sby have been determined from Fourier transform infrared spectroscopy measurements. The results show good agreement with those calculated from a semi-empirical interpolation method. The temperature dependence of band gap energy has also been investigated for an alloy sample with zd.247 and yd.907 at temperatures ranging from 10 to 300 K. While the energy gap varies approximately linearly with temperature for T > 100 K, with a temperature coefficient dEg/dT of -2.63x10-4 eV. K-1 , a nearly quadratic T-dependence of the band-gap shift exists for temperatures below the Debye temperature, which consists with that of most of semiconductors.
15 articles