Current Issue

Volume 12 Issue 2
Online Date:
Previous Issue    Next Issue
Original Articles
A Periodic Solution of Kdv Equation in Virasoro Algebra
YANG Kongqing
Chin. Phys. Lett. 1995, 12 (2): 65-67 .  
Abstract   PDF(pc) (131KB) ( 579 )
A new periodic travelling wave solution of Kdv equation is obtained in manifold Diffs1/ s1 ( t ) which is relevant to the coadjoint orbit Diffs1 / s1 of Virasoro group.
Systematics in the Improved NπNv Scheme
ZHAO Yumin, CHEN Yan
Chin. Phys. Lett. 1995, 12 (2): 68-71 .  
Abstract   PDF(pc) (191KB) ( 444 )
Systematics of energy spectra and B(E2) with substantial improvements in the NπNv scheme are presented. The correlation of energy spectra over an extended region is pointed out and a simple explanation is given. A method for verifying the simple B(E2) systematics is also suggested.
Finite - Nuclei Properties in Relativistic Density Dependent Hartree - Fock Approach
MA Zhongyu, SHI Hualin, CHEN Baoqiu
Chin. Phys. Lett. 1995, 12 (2): 72-75 .  
Abstract   PDF(pc) (229KB) ( 470 )
Finite nucleus properties are studied in a relativistic effective interaction approach. Density dependent coupling constants of the meson-nucleon interactions are adopted to incorporate the relativistic Brueckner- Har tree-Fock results in the relativistic mean field (RMF) or relativistic Hartree-Fock (RHF) approach. It is desired to remedy the deficiencies of RMF and RHF without losing the features of the relativistic G matrix and at the same time retain the simplicity. The calculated ground state properties with the density dependent coupling constants are in a good agreement with experiment. The contribution of isovector mesons in RHF is discussed.
Theoretical Calculations on Rare Earth Elements in Barium Fluoride Crystal
GU Mu, CHEN Lingyan, DU Jie, XIANG Kaihua
Chin. Phys. Lett. 1995, 12 (2): 76-78 .  
Abstract   PDF(pc) (155KB) ( 549 )
In the present work we used Hartree-Fock-Slater local-density discrete variational method to calculate the energy level of some rare earth doped BaF2 crystals and proposed that the Eu, Dy and Yb elements will change their valence from +3 to +2 under irradiation and thus change the optical properties of the crystals. The results show that this radiation effect model is in good agreement with experiments.
Squeezing of Field in the System of a Kerr Medium Embedded in a Nondegenerate Two-Photon Absorption Cavity
LI Gaoxiang, PENG Jinsheng, ZHOU Peng*
Chin. Phys. Lett. 1995, 12 (2): 79-82 .  
Abstract   PDF(pc) (218KB) ( 463 )
Squeezing properties of field in the system of a Kerr medium embedded in a nondegenerate two-photon absorption cavity interacting with a two-mode uncorrelated coherent field are discussed. We find that both the two-mode squeezing and the sum squeezing of field can arise and can be enhanced due to the Kerr effect.

Properties of Molten Potassium Niobate System
HONG Xinguo, LU Kunquan, ZHAO Yaqin, WU Xing
Chin. Phys. Lett. 1995, 12 (2): 83-86 .  
Abstract   PDF(pc) (223KB) ( 465 )
The density and surface tension of the K2 O-Nb2 O5 molten system between 50 and 56mol% K2 O melts were measured from 1080 to 1180°C. The concentration of K2 O from 50 to 56mol% in melt not only caused the density of melt to decrease, but also induced the surface tension to decrease. Both composition gradient and the temperature coefficient of density exist extremum within this composition range. These properties are possibly employed to explain why the KNbO3 crystal should be grown at the composition from 52 to 54mo1% K2 O at above 1150°C.

Effect of Laser Irradiation on the Optical Properties of Diamond-Like Carbon
CHENG Degang, LÜ, Fanxiu, YANG Rang, YE Ruizeng SUN Qingbiao
Chin. Phys. Lett. 1995, 12 (2): 87-90 .  
Abstract   PDF(pc) (182KB) ( 730 )
Magnetron sputtered diamond-like carbon (DLC) films were irradiated by cw CO2 laser. It was found that the laser irradiation increased the visible absorption, decreased the optical gap of DLC and decreased lightly the infrared transmittance. The absorption curves of the as-deposited and the irradiated films indicated that the irradiation decreased the hydrogen content and the sp3 hybrid structure and altered the absorption mode of C-CH3.
Vibrational Properties Study on Canter Fractal Structure
ZHANG Haifeng, TANG Tao, XU Wenlan, LI Yongping
Chin. Phys. Lett. 1995, 12 (2): 91-94 .  
Abstract   PDF(pc) (182KB) ( 500 )
A new system of Canter fractal models was created and studied, the density of states (DOS) as well as wavefunctions of the phonon in this kind of structure were calculated and discussed, in which it shows a new kind of branch rules for the DOS and new characteristics for the wavefunctions.
Existence of Localized Modes in a Purely Anharmonic Chain
WANG Shaofeng
Chin. Phys. Lett. 1995, 12 (2): 95-97 .  
Abstract   PDF(pc) (149KB) ( 465 )
For a monatomic one-dimensional chain of particles interacting via a nearest-neighbor purely anharmonic potential of any even order (such a chain is called purely anharmonic chain), it is proved that there really exist exact localized modes.
Scaling and Scaling-Relevant Dynamical Properties of Penrose Tiling
LIU Zhengyou, LIU Youyan, TIAN Decheng, XIA Haibo
Chin. Phys. Lett. 1995, 12 (2): 98-101 .  
Abstract   PDF(pc) (199KB) ( 495 )
The scaling and the scaling-relevant spectral properties of Penrose tiling are investigated. The fractal dimension df of this tiling is analytically obtained, which is two, equal to its Euclidean dimension. Similar to usual self-similar structure, the vibrational density of states for Penrose lattice is also found to follow a power law p(ω) ~ωds -1 with spectral dimension ds= 2 , which accounts for a special vibrational excitation in quasicrystals: the fracton-like excitation, whose state is critical. The simulation of random walk on this Penrose lattice indicates that the diffusive dimension dw= 2, thus the relation ds = 2df/dw holds.
Enhanced Stark Shift in GaAs/AlGaAs Step Quantum Well Under an Applied Electric Field
MA Jianwei, CHEN Zhenghao, CUI Dafu, YUAN Zhenyu, YANG Guozhen
Chin. Phys. Lett. 1995, 12 (2): 102-105 .  
Abstract   PDF(pc) (217KB) ( 760 )
Theoretical calculations of the quantum confined Stark shift for the first heavy hole exciton (hhl--el) in step quantum well are given. A significant change in Stark shift is achieved in specially stepped potential shape, which is more than two times larger than the conventional rectangular quantum well. The structure has the advantage of a large change in absorption, which is one of the best candidates for the optical modulators utilizing the quantum confined Stark effect (QCSE) in GaAs/AlGaAs. Relations between QCSE and stepped structure are discussed in the optimization for large Stark shift.
Periodic Wave Solution and Its Stability in Antiferromagnet KCuF3
LIU Wuming, ZHOU Benlian
Chin. Phys. Lett. 1995, 12 (2): 106-109 .  
Abstract   PDF(pc) (186KB) ( 436 )
Introducing the coherent state ansatz and the time-dependent variational principle, we obtain the two partial different equations of motion from Hamiltonian. Employing the method of multiple scales, we reduce these equations into the envelope function equation and find the amplitude function satisfied a nonlinear Schrödinger equation. We get the periodic wave solution and analyse its stability antiferromagnet KCuF3.
Size Effect in Ferroelectric Long Cylinders
WANG Yuguo, ZHANG Peilin, WANG Chunlei, ZHONG Weilie, N. Napp, D. R. Tilly
Chin. Phys. Lett. 1995, 12 (2): 110-112 .  
Abstract   PDF(pc) (136KB) ( 420 )
The Curie temperature and polarization in a ferroelectric cylinder with infinite length have been examined using Landau free energy expansion. The Curie temperature and polarization decrease with decreasing cylinder diameter for the positive extrapolation length, and reach zero at the critical size. For negative extrapolation length, both Curie temperature and polarization increase with decreasing cylinder diameter.

Suppression of Raman Self-Frequency Shift of Soliton Propagation in Single Mode Optical Fiber
XU Wencheng, GUO Qi, LIAO Changjun, LIU Songhao
Chin. Phys. Lett. 1995, 12 (2): 113-115 .  
Abstract   PDF(pc) (138KB) ( 543 )
A novel idea is proposed to suppress the soliton self-frequency shift of femtosecond soliton pulse in dispersion-decreasing fibers. The expression of the soliton self-frequency shift as a function of the pulse width and the fiber dispersion parameter is derived. The numerical simulation is also given, and is in agreement with analytical results.
Raman Scattering of Hydrogen-Ion-Exchanged LiNbO3 Crystal
Wu Xinglong, ZHANG Mingsheng, FENG Duan, LIU Zhengtao
Chin. Phys. Lett. 1995, 12 (2): 116-119 .  
Abstract   PDF(pc) (69KB) ( 469 )
Raman spectra of LiNbO3 crystals with different hydrogen-ion-exchanged time were examined. E(TO) and A1 (TO) modes appear gradually in the transverse A1- and E-symmetry spectra respectively with increasing the exchange time and the dependence of their intensities on the exchange time is also observed. We attribute these results to both the internal strains resulting from the ordering-disordering distribution of H ions in the sample and the enhanced photorefractive effect.
Heteroepitaxial Growth of Diamond Film on Cubic Boron Nitride Substrate by Hot-Filament Chemical Vapour Deposition
JIN Zengsun, LU Xianyi, ZOU Guangtian
Chin. Phys. Lett. 1995, 12 (2): 120-122 .  
Abstract   PDF(pc) (223KB) ( 595 )
Diamond films have been grown on high pressure synthesized cubic boron nitride (c-BN) particles by hot-filament chemical vapor deposition method, and heteroepitaxial diamond films on the c-BN (100) facets with no-evident defects were obtained, but polycrystalline diamond films were formed only on the c-BN (111) facets.
Effect of Hydrolysis Catalysts on Structural Evaluation of Sol-Gel Derived Titania Nanocrystalline Powders
DING Xingzhao, LUO Ju, QI Zhenzhong, HE Yizhen
Chin. Phys. Lett. 1995, 12 (2): 123-125 .  
Abstract   PDF(pc) (160KB) ( 451 )
Effect of hydrolysis catalysts (HCl and C5H8O2) on structural evaluation of gelderived nanocrystalline TiO2 powders was studied. Crystallization temperature of the HCl catalyzed gel is about 200K lower than that of the C5H8O2 catalyzed one. But in the later gel the anatase phase transforms to rutile at a lower temperature, and the transformation is completed in a much more narrow temperature range.
Discussion on the Chromosome Oscillation During Metaphase
TANG Xiaowei
Chin. Phys. Lett. 1995, 12 (2): 126-128 .  
Abstract   PDF(pc) (140KB) ( 382 )
The chromosome oscillation diving metaphase is explained as the result of fluctuation of forces exerted on the chromosome. In this letter a simple model for chromosome oscillation is proposed and the formulas of force fluctuation and the root mean square displacement of the chromosome in the oscillation are derived.
18 articles