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Volume 9 Issue 8
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Original Articles
Finite Size Corrections for One Dimensional Interacting Fermions
LIU Yimin, PU Fuque(Fu-Cho Pu), SU Hang
Chin. Phys. Lett. 1992, 9 (8): 393-396 .  
Abstract   PDF(pc) (200KB) ( 544 )
Using the method based on the Euler-Maclaurin formula, we calculate the finitesize correction to the energy of the ground state and the excited state for the delta interacting fermion gas in the periodic boundary condition with N - 1 of the N fermions having the same spin and one having the opposite spin. In the thermodynamic limit, we obtain the conformal anomaly, operator dimension and the correlation functions.

Reduction of Effective “Spring Constants” Using Gravitational Fields
ZHANG Pinghua*, R. D. Newman
Chin. Phys. Lett. 1992, 9 (8): 397-399 .  
Abstract   PDF(pc) (155KB) ( 455 )
We discuss the feasibility of operating a torsion balance in the presence-of fixed masses positioned so that a decrease in gravitational potential energy experienced by the balance as it rotates nearly cancels the positive energy associated with its twisting support fiber. Under these conditions the net effective torsion constant may in principle be made arbitrarily small. We dicuss an example of reduction by a factor of 100.
Two Proton Interferometry in 46.7 MeV/u 12C Induced Reactions
XI Hongfei, ZHAN Wenglong, ZHU Yongtai, GUO Zhongyan, HU Xiaoqing, LIU Guanhua, ZHOU Jianqun, YIN Shuzhi, ZHAO Youxiong, WE Zhiyong, FAN Enjie
Chin. Phys. Lett. 1992, 9 (8): 400-402 .  
Abstract   PDF(pc) (167KB) ( 485 )
The particle-particle (P-P) correlation functions are investigated in 46.7MeV/u12C induced reactions, the correlation functions are greatly enhanced at q~20 MeV/c when the sum of the energies of two correlated protons are high and almost independent on the targets. On the contrast, a strongly target dependent effect is observed for the P-P correlation functions when the sum energies are low.

Variation of Effective Mass and Level Density Parameter with Nuclear Temperature in Semi-infinite Nuclear Matter
HUANG Weizhi, WANG Zixing, P. F. Bortignon*, R. A. Broglia**
Chin. Phys. Lett. 1992, 9 (8): 403-406 .  
Abstract   PDF(pc) (207KB) ( 554 )
The temperature dependence of the self-energy of a particle is studied in semi-infinite nuclear matter. Based on the finite temperature Green’s function Mat-subara formalism and applying it to the single particle-states in 208Pb, the calculated results show that the characteristic enhancement of the effective mass at near the Fermi energy disappears at temperature T=3 MeV, and correspondingly, as a consequence the level-density parameter should decrease in agreement with recent empirical data.
Damage Patterns and Fractal Behavior of Polymeric Target Bombarded by Intense Pulsed Electron Beams
JIANG Xingliu, HAN Lijun*
Chin. Phys. Lett. 1992, 9 (8): 407-410 .  
Abstract   PDF(pc) (251KB) ( 430 )
The damage patterns created by the interactions of intense pulsed electron beams with polymeric targets reveals the processes of plasma channel formation and deposition of the beam energy and charge. There is a close structural similarity of the damage pat tern with the dielectric breakdown which naturally leads to fractal structure with an exponent D≈1.7.


Theory of Guided Electromagnetic Waves on Chiral Circular Rod Surface
QIU Caiming, LIU Shuzhang, LIN Weigan
Chin. Phys. Lett. 1992, 9 (8): 411-414 .  
Abstract   PDF(pc) (148KB) ( 413 )
We solve here a new structure of chiral rod surface waveguide, which has some potential applications. The eigenvalue equation is obtained, and when chirality ξc =0, it reduces to its counterpart of ordinary dielectric-rod waveguide.

Correlation Function of Clumps for Electrons in Localized Coherent Langmuir Fields
ZHOU Cangtao, HE Xiantu, ZHU Shaoping
Chin. Phys. Lett. 1992, 9 (8): 415-418 .  
Abstract   PDF(pc) (206KB) ( 442 )
A correlation function of electrons interacting with localized coherent Langmuir wave packets is obtained by particle simulation. It is shown that the peak behavior of the correlation function for sufficiently small relative coordinates r0 and u0 in phase space also occurs in a spatially inhomogeneous system, and the neighboring particles in phase space are correlated with each other for a lifetime exceeding the coherent time. Our numerical results display the clump effects, which are consistent with previous theoretical prediction of the relative diffusion behavior.

Self-Similarity of Quasi-Periodic Lattice
SUN Jirong
Chin. Phys. Lett. 1992, 9 (8): 419-422 .  
Abstract   PDF(pc) (176KB) ( 461 )
The self-similarity of arbitrary n-fold symmetry quasi-periodic lattice is investigated systematically. The general form of the inflation operator M is derived. A criterion for the existence of self-similarity is given mathematically.

One-Dimensional Vibrational Properties of Nanocrystalline Materials
ZHANG Haifeng
Chin. Phys. Lett. 1992, 9 (8): 423-426 .  
Abstract   PDF(pc) (216KB) ( 494 )
We have studied the vibrational properties of one-dimensional nanocrystalline materials. After creating the model, we studied the effects of the average size and the size distribution of nanocrystallites on the vibrational properties, and the effects of the proportion of the interfacial atoms to total atoms in each nanocrystallities are also discussed.

Refractive Index Measurement and Second Harmonic Generation in a Series of LiNbO3:Mg (5mol%) Crystals
CHANG Yongmao, WEN Jinke, WANG Huafu, LI Bing
Chin. Phys. Lett. 1992, 9 (8): 427-430 .  
Abstract   PDF(pc) (246KB) ( 837 )
The accurate refractive indices in visible range and their Sellmeier equations have been obtained for a series of LiNbO3 :Mg (5mol%) crystals with Ti or Nd doping. The phase matching angle for 1.064μm calculated by Sellmeier equation gives good agreement with experimental value. The TiO2 and Nd2O3
doping cause the decrease of the birefringence and the increase of the phase matching angle. The conversion efficiency is enhanced by TiO2 doping. The second harmonic generator with conversion efficiency of more than 44% has been achieved at room temperature with phase matching angle close to 90 °.


Spectrum of Third Harmonic Generation of MX Complex
LI Lieming, SUN Xin, K.Nasu*
Chin. Phys. Lett. 1992, 9 (8): 431-434 .  
Abstract   PDF(pc) (177KB) ( 401 )
The theory of third harmonic generation of MX complex is presented on the basis of charge density wave model. The recently observed spectrum x(3) ( ω ) of Pt-Cl complex can be well interpreted by this theory, which shows that the experimental peak at 1.8eV is produced by the two-photon resonance between the bottom of valence band and the top of conduction band. Besides, our theory predicts that there exist another peak below the observed region.


Lyapunov Exponent Spectrum for Two-Mode Model in Spin-Wave Chaos
HE Yuquan, CHI Ruidong, YU Jinlong
Chin. Phys. Lett. 1992, 9 (8): 435-437 .  
Abstract   PDF(pc) (188KB) ( 465 )
The results of numerical experiments on the two-mode model for yttrium iron garnet sphere in the parallel-pumping configuration are reported and the complete Lyapunov exponent spectrum is presented. A rather complicated structure of the Lyapunov exponent spectrum can be recognized by the appearance of the associated peak in the Kolmogorov-Sinai entropy and the Lyapunov dimension diagrams. The results confirm an important connexion between the effective number of spin-wave modes involved and the Lyapunov dimension of the attractors.
Temperature Dependence of Photoluminescence in Porous Silicon
FANG Rongchuan, LI Qingshan, CUI Jingbiao
Chin. Phys. Lett. 1992, 9 (8): 438-440 .  
Abstract   PDF(pc) (172KB) ( 468 )
Porous silicon samples have been successfully prepared by elect rochemical etching technique, which show intense photoluminescence (PL) in the visible wave-length region. The measurements of the temperature dependence of PL in porous silicon show that the wavelength of the luminescent peak shifts to the blue and the PL band width does not change as the temperature of the sample increases over a wide range. The intensities of PL are measured as a function of temperature showing the confined exciton recombination behaviour, and the activation energies of 68.6 and 205meV of the excitons have been obtained for the low temperature and high temperature regions, respectively. The results suggest that the PL in porous silicon is due to the radiative recombination in a quantum wire system.



Specific Heat Anomaly of Lithium Sodium Niobate at Low Temperature
ZHANG Peilin, ZHONG Weilie, ZHAO Shaoxiang, YANG Zhaohe*, CHEN Huanchu*, SONG Yongyuan*
Chin. Phys. Lett. 1992, 9 (8): 441-443 .  
Abstract   PDF(pc) (152KB) ( 812 )
A differential scanning calorimetric (DSC) study of the crystal Li0.02Na0.98NbO3 was carried out in the temperature range from 120 to 300K. The specific heat changes anomalously at about 180K on cooling and about 260K on heating, implying a first order phase transition. The heat of transition ΔQ=(212±50)J/mol and the corresponding change in entropy AS=0.82J/mol.K. The thermal hysteresis of this transition is about 80K, in agreement with that previously obtained from the dielectric and pyroelectric measurements.

High Growth Rate of Diamond Films by DC Plasma CVD Using Organic Compounds
WANG Wanlu, GAO Jinying, LIAO Kejun
Chin. Phys. Lett. 1992, 9 (8): 444-447 .  
Abstract   PDF(pc) (267KB) ( 711 )
Diamond film have been synthesized by dc plasma chemical vapour deposition (CVD) from a gaseous mixture of acetone and hydrogen gases with a growth rate of 220μm/h. The films obtained have good crystallinity that are chaxacte-ized by Raman spectrometry, scanning electron microscopy and x-ray diffraction. X-ray photoelectron spectroscopy analysis have confirmed that diamond nucleation and growth are on SiC rather than on clean Si. The mechanism of high rate growth diamond film have been discussed too.
KNbO3: Fe Optical Frequency Discriminator
ZHANG Zhiguo, JIANG Qian, MI Xin, YU Zuhe, FU Panming, SHEN Dezhong*, MA Xiaoyan*
Chin. Phys. Lett. 1992, 9 (8): 472-475 .  
Abstract   PDF(pc) (207KB) ( 522 )
By using the feature that KNbO3:Fe bas fast response time, we demonstrate a KNbO3:Fe optical frequency discriminator (KOFD) which is based on the method of the-delayed laser-induced double)le gratings. This KOFD can be used to measure the frequency difference between two laser fields.
16 articles