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Volume 13 Issue 8
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Original Articles
An Explicit Exact Solution of a Nonlinear Schrödinger Equation for Short Ultraintense Laser Pulse in an Underdense Plasma
GAO Hong-jun
Chin. Phys. Lett. 1996, 13 (8): 561-564 .  
Abstract   PDF(pc) (122KB) ( 417 )
A nonlinear Schrödinger equation for short ultraintense laser pulses in an underdense plasma has been discussed, and three types explicit exact solutions of this equation are obtained by using analytical method.
Exact Solution of Persistent Currents in One-Dimensional Mesoscopic Rings with Consideration of Electron-Phonon Coupling
WANG Ke-lin, WANG Mao-xi
Chin. Phys. Lett. 1996, 13 (8): 565-567 .  
Abstract   PDF(pc) (104KB) ( 415 )
With a new nonperturbative method, the problem of persistent currents in one-dimensional mesoscopic rings with consideration of electron-phonon coupling is exactly solved and the energy spectrum is obtained. The result of this paper means that in the case of tight-binding model consideration of persistent currents can be treated separately from the interaction of electronphonon interaction.
A Model of Vertical Isolation System with Gravitational Positive Feedback
ZHAO Peng-fei, LUO Jun, ZHANG Ping-hua
Chin. Phys. Lett. 1996, 13 (8): 568-571 .  
Abstract   PDF(pc) (183KB) ( 381 )
An ideal model of vertical isolation system with gravitational positive feedback is proposed and some properties are discussed. The theoretical analysis shows that the resonant frequency of the system could be reduced much efficiently by means of a negative spring coefficient.
Communication via Chaotic Synchronization Based on Contraction Maps
ZHOU Chang-song, CHEN Tian-lun
Chin. Phys. Lett. 1996, 13 (8): 572-575 .  
Abstract   PDF(pc) (190KB) ( 417 )
A newly proposed method for constructing chaotically synchronizing systems is applied to communication. Several independent information signals can be transmitted at the same time if the chaotic system is a multi-dimensional one. Robustness of the method is investigated.
A High-Spin Isomer in l98Bi
ZHOU Xiao-hong, SUN Xiang-fu, GUO Ying-xiang, LEI Xiang-guo, CHEN Xin-feng, LIU Zhong, ZHANG Yu-hu, JIN Han-juan, LUO Yi-xiao, WEN Shu-xian*, YUAN Guan-jun*, LI Guang-sheng*, YANG Chun-xiang*
Chin. Phys. Lett. 1996, 13 (8): 576-578 .  
Abstract   PDF(pc) (157KB) ( 435 )
High-spin states in l98Bi were populated via the 187Re (l6O, 5n) reaction. A partial level scheme for l98Bi was established for the first time, including a 15+ high-spin isomeric state with a measured half-life of 8.0± 3.6ns. By comparing the level structure of l98Bi with that of the even-even core 198Pb, the configuration v (i13/2)-2 v (P3/2)-1 π (hg/2)1 was ascribed to this isomeric state.
Spectroscopic Properties of Sr 5p1/2ns Autoionizing States
DAI Chang-jian, LÜ, Jun
Chin. Phys. Lett. 1996, 13 (8): 579-582 .  
Abstract   PDF(pc) (268KB) ( 363 )
The resonance profile of the Sr 5p1/2ns states and angular dependence of ejected electrons have been studied by using three-step excitation scheme. Energy levels and widths of the 5p1/2ns states with n ranging from 7 to 10 are measured. The electrons originated from the decays to different ionic states are resolved with the time-of-flight detector.
Effects of Correlated Noises on Statistic Property of Single-Mode Laser
WEI Xue-qin, CAO Li, WU Da-jin
Chin. Phys. Lett. 1996, 13 (8): 583-586 .  
Abstract   PDF(pc) (149KB) ( 380 )
The loss-noise model with saturation effects driven by correlated additive and multiplicative white noise is studied. An analytical expression of the stationary probability distribution is obtained. The mean, variance and skewness of the steady-state laser intensity are calculated numerically. We have also found the correlated noises affect the statistic properties of laser heavily. Moreover, the laser intensity is locked at a fixed value when correlated parameter λ is equal to -1.

On the General and Resonant Solutions of Atoms Reflected by an Evanescent Laser Wave
TAN Wei-han, LI Qiang-ning
Chin. Phys. Lett. 1996, 13 (8): 587-589 .  
Abstract   PDF(pc) (117KB) ( 373 )
Usually the reflection of two level atoms by a detuning evanescent laser wave was studied in past few years.1-3 In previous paper we have presented an exact solution for this model based on the matrix Laplace transformation technique, and proceeded the numerical calculations for a given set of parameters.4 However in the special case of resonance interaction considered in this paper, the solution for Schrödinger wave equation and reflectivity calculation can be greatly simplified; besides, the resonant solution provides a check to the numerical data based on the general solution of the previous paper.

A Method for Effective Population Transfer in U Vapor with Doppler Effect and Collision
NING Xi-jing, JING Chun-yang, LIN Fu-cheng
Chin. Phys. Lett. 1996, 13 (8): 590-593 .  
Abstract   PDF(pc) (238KB) ( 387 )
We proposed a method for effective population transfer in an atomic vapor with Doppler effect and collision. Using this method, we have demonstrated that an efficient population transfer occurs in 238U vapor produced in a hollow-cathode discharge tube. A numerical calculation with density matrix agrees well with our experimental result and indicates that the method can be used to raise the efficiency of atomic vapor isotope separation.
Coupling Alfvénic and Ion-Acoustic Solitons
WU De-jin, WANG De-yu, Carl-Gunne Fä, lthammar*
Chin. Phys. Lett. 1996, 13 (8): 594-597 .  
Abstract   PDF(pc) (187KB) ( 574 )
An exact nonlinear equation governing the coupling Alfvénic and ion-acoustic solitons and criterion for their existence are presented. For the case of low-β plasmas, the two modes decouple. In the small amplitude limit, the analytical results lead to KdV solitons.


Self-Consistent Flow Shear Induced by Drift-Thermal Turbulence
PENG Xiao-dong, GAO Qing-di
Chin. Phys. Lett. 1996, 13 (8): 598-601 .  
Abstract   PDF(pc) (199KB) ( 452 )
The self-consistent poloidal flow shear induced by turbulence driven by impurity radiation has been studied analytically. A set of reduced equations is obtained. In our system, three equilibrium states exist. The first is the zero flow shear state, which is relevant to the behavior such as L mode; the second is the positive flow shear state, which is relevant to the behavior such as dithering H mode; and the third is the negative flow shear state, which is relevant to the behavior such as edge-localized modes.
Effects of Lu3+ Doping on Optical Properties and Laser Performances of NYAB Crystal
PAN Heng-fu, WANG Pu, FAN Xiao-feng, WANG Rui-hua, LU Bao-sheng
Chin. Phys. Lett. 1996, 13 (8): 602-605 .  
Abstract   PDF(pc) (176KB) ( 795 )
Volume compensation (VC) achieved in (Lu, Nd):YAl3 (BO3)4 (YAB) crystal codoped with Lu3+ and Nd3+ ions is described. The lattice parameters, spectral properties and laser performances of the VC (Lu, Nd):YAB and single-doped Nd: YAB (NYAB) crystals are measured and compared. The results indicate that the laser performances of NYAB crystal can be greatly improved by the VC doping.



Real-Time Investigation of the Growth Kinetics of an Organometallic Complex Crystal ATMB
SUN Yi, YU Xi-ling, HOU Wen-bo, ZHANG Shu-jun, GUO Shi-yi
Chin. Phys. Lett. 1996, 13 (8): 606-609 .  
Abstract   PDF(pc) (312KB) ( 479 )
This paper reports the growth kinetics of a new kind of organometallic complex crystal triallylthiourea mercury bromide (ATMB), investigated by in situ microscopic observation. The step trains formed by the layer growth mechanism have larger width (ranged from 2 to 15μm) and lower height (40-250nm). The relationship between the growth rate R and the relative supersaturation σ was obtained by directly measuring the movement of step trains of ATMB crystal in aqueous solution. The variation of growth mechanism with supersaturation σ is also discussed.




Thermal Conductivity of Diamond-Based Silicon-on-Insulator Structures
GU Chang-zhi, JIN Zeng-sun, LU Xiang-yi, ZOU Guang-tian, LU Jian-xia, YAO Da, ZHANG Ji-fa, FANG Rong-chuan
Chin. Phys. Lett. 1996, 13 (8): 610-612 .  
Abstract   PDF(pc) (166KB) ( 413 )
Diamond films of various thickness (1-300μm) were deposited on single-crystal Si active (300 μm) by a microwave plasma chemical vapor deposition method using gaseous mixtures of methane and hydrogen. After thinning of the Si layer by machine and ion-beam polishing a diamond-based silicon-on-insulator structure with final Si layer thickness of about 1μm is formed. Thermal conductivity of this structure material with various thicknesses of diamond and Si layer was measured. Compared with bulk silicon, the thermal conductivity of the siliconon-diamond structure with 300μm diamond and 1μm silicon increases by 850%.


Growth and Luminescence of SiGe Self-organized Dots
CHEN Hong, XIE Xiao-gang, CHENG Wen-qin, HUANG Qi, ZHOU Jun-ming
Chin. Phys. Lett. 1996, 13 (8): 613-616 .  
Abstract   PDF(pc) (327KB) ( 480 )
It is found that the SiGe alloy self-organizes into uniform quantum dots embedded in the silicon layer during the growth of strained SiGe/Si rnultilayers on a Si (001) substrate by molecular beam epitaxy. The energy of photoluminescence from the quantum dots is higher than the indirect band-gap of Si, and the luminescence of the quantum dots exceeds that of quantum well by three orders of magnitude. This can be attributed to an indirect-to-direct band-gap conversion in the SiGe dots.
On Optical Polarons in One Dimensional Molecular-Crystal Chains
CHEN Hao, CHEN Yuan
Chin. Phys. Lett. 1996, 13 (8): 617-620 .  
Abstract   PDF(pc) (147KB) ( 422 )
An improved solution for the optical polarons in the molecular-crystal model with the dispersion term in one dimensional chains is found. Under approximation neglecting the dispersion term, the improved solution tends to usual optical polarons solution. The self-trapped well of the electron is calculated.
Domain Patterns and Phase Transitions in Ferroelectric Crystal KNbO3
LIU Xian-jie, ZHANG Xing-kui, XU Xiu-ying
Chin. Phys. Lett. 1996, 13 (8): 621-624 .  
Abstract   PDF(pc) (455KB) ( 373 )
We have studied the domain configurations and structures of KNbO3 crystal in orthorhombic and tetragonal phases by polarizing microscopy. The phase transition processes among orthorhombic, tetragonal and cubic phases and thermal hysteresis during phase transitions are observed directly. Domain-pattern changes and the stable domain patterns during the phase transitions are discussed.

Deposition of Diamond Film on Aluminum Nitride Ceramics and the Study of Their Thermal Conductance
CHEN Hong, ZHANG Ji-fa, CUI Jing-biao, FANG Rong-chuan*
Chin. Phys. Lett. 1996, 13 (8): 625-628 .  
Abstract   PDF(pc) (535KB) ( 539 )
Diamond films (DF) have been deposited on AlN ceramic substrates by hot filament chemical vapour deposition method. The diamond nucleation on AlN ceramics has been investigated. A nucleation density more than 108 cm-2 was obtained on this kind of insulating polycrystalline substrate under common deposition conditions. The thermal conductance of the DF/AlN compound materials has been studied by photothermal deflection technique. The thermal diffusivity of the DF/AlN is higher than that of the AlN ceramics, and will increase as the diamond films grow thicker.
Effect of Noise on the Dynamics of Neuronal Network
LIU Feng, WANG Wei, YAO Xi-xian
Chin. Phys. Lett. 1996, 13 (8): 629-632 .  
Abstract   PDF(pc) (225KB) ( 382 )
The structure of spatiotemporal pattern and the dynamical behavior of interspike timeinterval sequences of firings in a coupled noisy neuronal network are investigated. Various types of external stimuli have been used to exert on the network. The dynamics is modulated by animpulse-like synaptic current which is modeled as globally coupling interactions in the network. The peaks in the interspike interval histogram of spikes are located at integer multiples of the external period, which corresponds with experimental results.
Hawking Radiation of Dirac Particles in 1+1 Dimensional Nonstatic Black Hole
CHEN Da-ming, SHEN You-gen, SONG Guo-xuan
Chin. Phys. Lett. 1996, 13 (8): 633-636 .  
Abstract   PDF(pc) (143KB) ( 450 )
This letter is devoted to the discussion of the Hawking radiation of Dirac particles in 1 + 1 dimensional space-time. The general nonstatic 1 + 1 dimensional metric is used to calculate the radiant spectrum and the expression of radiation temperature, which, as an example, verifies the quantum-mechanical instability in black hole due to Hawking radiation.

Property Changes of Gamma-Ray Bursts
LI Ti-pei
Chin. Phys. Lett. 1996, 13 (8): 637-640 .  
Abstract   PDF(pc) (234KB) ( 445 )
From analysing the third burst and transient source experiment gamma-ray burst catalog, systematic variations of average observational characteristics of γ-ray bursts (GRBs) with a time scale of months to years are revealed, which raise a difficulty to existing models and indicate an origin of GRBs, at least partly, within the heliosphere. A possible GRB producing process is discussed.

21 articles