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Volume 14 Issue 11
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Original Articles
Quantum Phases of Pancharatnam Type for a General Spin in a Time-Dependent Magnetic Field
ZHAO Yue-gang, LI Bo-zang
Chin. Phys. Lett. 1997, 14 (11): 801-804 .  
Abstract   PDF(pc) (210KB) ( 340 )
Based on the quantum invariant theory, the quantum phases, including the total phase as well as its dynamical and geometric parts, of Pancharatnam type are derived for a general spin in a time-dependent magnetic field, without the constraint of adiabatic, cyclic or unitary condition. The geometric meaning of geometric phase is expounded.
Loss and Revival of Atomic Interference
GUO Guang-can, ZHENG Shi-biao
Chin. Phys. Lett. 1997, 14 (11): 805-807 .  
Abstract   PDF(pc) (147KB) ( 343 )
The which-path micromaser detector and the associated quantum eraser are proposed based on the interactions of atoms with a cavity placed in front of one of the double slits in an atomic interferometer.
Wehrl’s Entropy and Noise
WU He-jun, XIA Yun-jie
Chin. Phys. Lett. 1997, 14 (11): 808-811 .  
Abstract   PDF(pc) (145KB) ( 489 )
The relations between Wehrl’s entropy and squeezing or total noise in the field with Gaussian Q function are established, The results show that, the Wehrl’s entropy will be reduced when the squeezing is increased or the total noise is decreased. The other nonclassical properties in this kind of field are also discussed.
Two Theorems for General n-Mode Boson Exponential Quadratic Operators
XU Xiu-wei, ZHANG Yong-de
Chin. Phys. Lett. 1997, 14 (11): 812-815 .  
Abstract   PDF(pc) (188KB) ( 737 )
By the aid of the generalized linear quantum transform theory, we present for the multimode boson exponential quadratic operators two theorems to change the operator expressions among usual, normal and anti-normal orderings.
Synchronization of Conservative Flow
LIU Zong-hua, CHEN Shi-gang
Chin. Phys. Lett. 1997, 14 (11): 816-819 .  
Abstract   PDF(pc) (232KB) ( 457 )
Two identical chaotic systems of conservative flow are shown to be synchronous by applying periodic pubes at a regular time interval. This idea is illustrated with a numerical example. It is robust against external noise.
A Generalized Frenkel-Kontorova Model with Morse Potentials
XU Ai-guo, WANG Guang-rui, CHEN Shi-gang
Chin. Phys. Lett. 1997, 14 (11): 820-822 .  
Abstract   PDF(pc) (169KB) ( 456 )
A generalized Frenkel-Kontorova model with the Morse potentials is studied. The phase diagram reflects the nonlinear nature of the Morse potential. The correspondences of the ground states and the orbits of the area-preserving map are studied numerically. Our results present a better simulation to the real systems.
Controlling Spatiotemporal Chaos Using Nonlinear Feedback Functional Method
FANG Jin-qing, M.K.Ali, FANG Qing
Chin. Phys. Lett. 1997, 14 (11): 823-826 .  
Abstract   PDF(pc) (236KB) ( 584 )
Nonlinear feedback functional method for controlling spatiotemporal chaos is presented. As a key point, some typical kinds of nonlinear feedback functions are given. The efficiency and robustness of the method based on the flexibility of choices of nonlinear feedback functions are discussed.
Satellite Structure for Valence Shell of Methane by Electron Momentum Spectroscopy
FAN Xiao-wei, ZHANG Qing-xiang, ZHOU Shao-jie, DENG Jing-kang, ZHENG Yen-you, CHEN Xue-jun
Chin. Phys. Lett. 1997, 14 (11): 827-829 .  
Abstract   PDF(pc) (128KB) ( 460 )
The first extensive electron momentum spectroscopy study of the satellite structure in the inner valence region of methane at 1200eV is reported. The experimental momentum profiles belonging to the (2a1)-1 satellite state are presented at energies 25.3, 28.5, 31.5, 35.5eV, and compared with the 146-G(CI) calculation.
On the Zero-Order Diffraction of Phase Mask
WEN Peng-yue, CUI Xiao-ming, LIU Hong-du, E. Y. B. Pun, P. S . Chung
Chin. Phys. Lett. 1997, 14 (11): 830-833 .  
Abstract   PDF(pc) (168KB) ( 388 )
The zero-order diffraction of phase grating mask is analysed for rectangular and sinusoidal corrugated profiles, and a novel method is proposed for determining the depth and duty cycle parameter by the diffraction measurement at different wavelengths.
Alternating Linear Polarization State in a Neodymium-Doped Fiber Laser with Modulated Pump
YANG Qian-suo, WANG Peng-ye, DAI Jian-hua, ZHANG Hong-jun
Chin. Phys. Lett. 1997, 14 (11): 834-837 .  
Abstract   PDF(pc) (213KB) ( 526 )
we present an analysis for the alternating linear polarization (ALP) state in a multi-longitudinal-mode laser with external modulation, and propose a new method for detecting this state. In a neodymium-doped fiber laser with a modulated pump, the ALP state is experimentally observed at both periodic and chaotic oscillation.
Enhanced Photorefractive Properties of a Rh-Doped BaTiO3 Crystal at Elevated Temperature
CHI Ming-jun, DOU Shuo-xing, GAO Hong, SONG Hong-wei, ZU Ji-feng, ZHU Yong, YE Pei-xian
Chin. Phys. Lett. 1997, 14 (11): 838-841 .  
Abstract   PDF(pc) (206KB) ( 530 )
Two-beam coupling and self-pumped phase conjugation properties of a Rh-doped BaTiO3 crystal were investigated at 633nm as the temperature was increased from 20 to 50°C. A significant decrease in response time and an increase in gain of two-beam coupling were obtained. The self-pumped phase conjugation reflectivity was increased from 45 to 64% in this temperature range.
Photorefractive Effect in Poly (N-Vinylcarbazole) Composite with Fullerene
CHEN Zhi-jian, XU Li-fang, HUANG Zhi-wen, GONG Qi-huang, ZHANG Zhi-jie, CHEN Yi-wang, CHEN Hui-ying
Chin. Phys. Lett. 1997, 14 (11): 842-844 .  
Abstract   PDF(pc) (185KB) ( 514 )
The photorefractive effect was observed in poly(N-vinylcarbazole) composite films doped with electro-optic chromophore 2,5-dimetly-4(p-nitrophenylazo) anisole, plasticizer N-ethylcarbazole and different content fullerene C60. Their two-beam coupling experiment was performed by using a cw He-Ne laser at 632.8nm. The two-beam-coupling gain coefficient as higher as 140cm-1 was measured at poling dc electric field of 76V/μm and it was also found to be relied on the content of photosensitizer C60.

Direct Approach for Kink Solution of Ф - 4 Equation Under Perturbation
TANG Yi, YAN Jia-ren, CHEN Zhen-hua
Chin. Phys. Lett. 1997, 14 (11): 845-849 .  
Abstract   PDF(pc) (115KB) ( 502 )
Perturbations about kink solution of Ф- 4 equation are investigated by a direct approach which was recently developed in a study of soliton perturbation theory. In this scheme, the derivative expansion method from classical perturbation theory is employed to linearize the perturbed equation. The solution of the linearized equation for first-order correction is derived by the method of Laplace transformation. At the same time, the parameters variation is obtained directly from the secularity conditions.
Surface Plasmon Resonance Investigations of Photoinduced Changes in Liquid Crystalline Azobenzene Polymer Langmuir-Blodgette Films
GU Jian-hua, CHEN Yi-wen, LIANG Bing-jie, LU Bin, LU Zu-hong
Chin. Phys. Lett. 1997, 14 (11): 849-852 .  
Abstract   PDF(pc) (215KB) ( 413 )
In this letter, we report a novel phenomenon of photoisomerization-induced changes in liquid crystalline azobenzene polymers P12 Langmuir-Blodgette monolayer deposited on gold film by irradiating the monolayer with UV(360nm) and blue (450nm) lights, which was investigated by surface plasmon resonance technique. It has been shown that it is possible to switch the refractive indices reversibly by irradiating these films with light of appropriate wavelength.
A Novel Nonlinear Optimization Method of Inversion for Sea-Bottom Properties
XIAO Ling, ZHANG Ren-he, LI Feng-hua
Chin. Phys. Lett. 1997, 14 (11): 853-856 .  
Abstract   PDF(pc) (165KB) ( 408 )
A nonlinear optimization method is proposed to inverse the sea-bottom properties. The method is called seed division algorithm (SDA) and can be used to solve global optimization problem. A numerical test is carried out to inverse the sea-bottom properties. The test is based on SDA and beam displacement ray mode theory.
Nonlinear Plasma Oscillation with a Fractional Harmonics and Analysis in the Time-Frequency Spectrum
HUANG Guang-li, LI You-ping, HUANG Guang-yuan, Bengt Holback
Chin. Phys. Lett. 1997, 14 (11): 857-860 .  
Abstract   PDF(pc) (208KB) ( 430 )
In the observations of Freja satellite in the energization region of the low aurora (1700 km), a new nonlinear plasma oscillation with a turbulent spectrum at the fractional harmonics of the local proton gyrofrequencies is reported and analyzed with the wavelet transformation in the time-frequency spectrum.

Brillouin Instability in Underdense Plasma Under an Intense Laser Field
LIU Shi-bing, CHEN Shi-gang
Chin. Phys. Lett. 1997, 14 (11): 861-864 .  
Abstract   PDF(pc) (226KB) ( 333 )
The dispersion relation of the ion acoustic wave in an intense laser field is obtained by using a nonequilibrium distribution function. The Brillouin scattering instability is examined by numerical method.
Improvement of Friction and Wear Resistance for Ta or Ta+C Implanted H21 Steel
YANG Jian-hua, LIANG Hong, ZHANG Tong-he, SU Yi, ZHANG Tao
Chin. Phys. Lett. 1997, 14 (11): 865-868 .  
Abstract   PDF(pc) (272KB) ( 564 )
Ta and C ions extracted from a metal vapor vacuum arc ion source were implanted into H21 steel, with an implantation dose of 3 x 1017cm-2, extraction acceleration 42kV, and average ion beam flux about 40μ Rutherford backscattering spectrum was used to measure the surface composition after Ta or Ta+C implantation. Observation of phase induced by Ta and C implantation was carried out by x-ray diffraction analysis. Experimental results showed that the wear rate of the implanted layer dropped 30% for Ta ion implantation and by a factor of 2.5 for Ta+C dual ion implantation. Thus Ta+C dual ion implantation was found to significantly reduce the friction coefficient of H21 steel. The wear mechanisms of the implanted layer were discussed.
Density Oscillation Induced by an Interface
WANG Shao-feng, WANG Zhong-cheng, ZOU Shi-chang
Chin. Phys. Lett. 1997, 14 (11): 869-872 .  
Abstract   PDF(pc) (228KB) ( 377 )
An asymptotic expression for the density oscillation induced by an interface has been derived analytically by using a method which is equivalent to stationary phase approximation. The effects of the geometric structure of the Fermi surface and reflected amplitude are shown explicitly. The results provide a model-independent interpretation for some common features observed recently in the magnetic multilayer experiments.
Origin of the Fine Structure of Ultraviolet and Visible Spectra of Silicon Nanocolloids in 2-Propanol
ZHU Yong, ZHANG Li-de
Chin. Phys. Lett. 1997, 14 (11): 873-875 .  
Abstract   PDF(pc) (172KB) ( 607 )
The origin of the fine structure of ultraviolet and visible absorption spectra of silicon nanocolloids in 2-propanol prepared in Ar atmosphere by a new sputtering method is studied. The fine structure is described by phonon-electron coupling in electron transition of silicon. On the basis of the structure model of Si-Si4-nOn(n = 0, 1,2,3,4), an energy relation has been proposed to explain the fine structure. The fine structure indicates strong multiple phonon absorption which depends on that how many oxygen atoms the silicon atom bonds to.
Photoelectric Properties of Si-Sil-xGex-Ge Heterostructures for Infrared Detector
JIANG Ruo-lian, JIANG Ning, GU Shu-lin, LI Zhao, XU Jun, ZHU Shun-ming, HU Li-qun, ZHENG You-dou
Chin. Phys. Lett. 1997, 14 (11): 876-878 .  
Abstract   PDF(pc) (202KB) ( 423 )
Si-Sil-xGex-Ge heterostructures with Ge fraction graded linearly from 1 to 0 have been epitaxially grown on Ge substrates by rapid, thermal process/very low pressure-chemical vapor deposition. The peak value of the spectrum response for these structures ranges from 1.3 to 1.55 μm, which is just in accordance with the optical fiber communication window, and considered to be the superposition of the response in Sil-xGex absorption region and the Ge absorption region. High detecting sensitivity, and low dark current have been achieved from the prototype SiGe ptype intrinsic n-type photodetectors made of these structures.

Comment on “Local Cooling Effect of Rotation and Formation of Thermal Barrier in Tokamaks”
SHI Bing-ren, QIN Yun-wen
Chin. Phys. Lett. 1997, 14 (11): 879-879 .  
Abstract   PDF(pc) (85KB) ( 313 )
Reply to SHI Bing-ren and QIN Yun-wen’s Comment
QIU Xiao-ming, DING Ning
Chin. Phys. Lett. 1997, 14 (11): 880-880 .  
Abstract   PDF(pc) (78KB) ( 340 )
23 articles