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Volume 17 Issue 1
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Original Articles
A Family of Interesting Exact Solutions of the Sine-Gordon Equation
HUANG De-Bin, LIU Zeng-Rong, WANG Li-Lian
Chin. Phys. Lett. 2000, 17 (1): 1-3 .  
Abstract   PDF(pc) (197KB) ( 383 )
By using AKNS [Phys. Rev. Lett. 31 (1973) 125] system and introducing the wave function, a family of interesting exact solutions of the sine-Gordon equation are constructed. These solutions seem to be some soliton, kink, and anti-kink ones respectively for the different choice of the spectrum, whereas due to the interaction between two traveling-waves they have some properties different from usual soliton, kink, and anti-kink solutions.
Influence of Fermion Determinant on the Temperature Dependence of Gluon Condensates
LIU Jue-Ping
Chin. Phys. Lett. 2000, 17 (1): 4-6 .  
Abstract   PDF(pc) (264KB) ( 439 )
The contribution of the fermion determinant to the gluon condensates at a finite temperature is calculated in the framework of the grand partition function for a weak-interacting instanton medium of a disordered phase. It is found that the temperature behavior of both chromomagnetic and chromoelectric gluon condensates depends sensitively on the flavor number. The more the flavors are, the faster the gluon condensates decrease. In the three-flavor are, the gluon condensates would be vanish (or the scale invariance would be restored) approximately at the temperature of 180MeV.

Structure of H-Dihyperon
SHEN Peng-Nian, , ZHANG Zong-Ye, YU You-Wen, YUAN Xiu-Qing, YANG Shu
Chin. Phys. Lett. 2000, 17 (1): 7-9 .  
Abstract   PDF(pc) (305KB) ( 421 )
The structure of H dihyperon (DH) is investigated by employing the SU (3) chiral quark model. As the structure of DH, two different configuations, six-quark cluster configuration and two-cluster configuration, are considered, respectively. The result shows that except the σ chiral field, the overall effect of the other SU (3) chiral fields is destructive in forming a stable DH and the two-cluster configuration is the preferred structure. The resultant mass of DH in a three-coupled-channel calculation in the SU (3) chiral quark model is ranged from 2225 to 2234 MeV.

A Qualitative Analysis of Channel Wave Functions and Widths of the Low-lying States of 6Li
BAO Cheng-Guang
Chin. Phys. Lett. 2000, 17 (1): 10-12 .  
Abstract   PDF(pc) (255KB) ( 377 )
The structure of the channel wave functions of 6Li is studied qualitatively. It is found that the widths of the low-lying resonances can be in general explained by using shell model wave functions. Nonetheless, the width of the 3+ state is narrower than that anticipated by the shell model, thus there is a room for the existence of other physical pictures to describe the very light nuclei.
Nonlinearity of the Dipole Moment Surface and Intensities Anomaly of CHCl3
LIN Hai, YUAN Lan-Feng, WANG Dong, ZHU Qing-Shi
Chin. Phys. Lett. 2000, 17 (1): 13-15 .  
Abstract   PDF(pc) (263KB) ( 384 )
Relative absorption intensities of the Fermi resonance polyads of isolated C-H chromophore for the CHCI3 molecule are calculated by one-dimensional dipole moment surface which had been obtained by the ab initio density functional method B3PW91 with 6-311++G(3df, 2pd) basis set, and agree very well with the experimental results. It is shown that the nonlinearity of the dipole moment surface in the vicinity of the equilibrium configuration is responsible for the intensities anomaly, i.e. the unusual strong intensities of the second Fermi resonance polyad.

A Statistical Theory for Hydrogen Bonding Networks: One Component Case
WANG Hai-Jun, BA Xin-Wu, ZHAO Min, LI Ze-Sheng
Chin. Phys. Lett. 2000, 17 (1): 16-18 .  
Abstract   PDF(pc) (259KB) ( 517 )
The theory of reversible gelation is shown to be applicable to the hydrogen bonding system by analyzing their similarities in statistical viewpoint. The size distribution of hydrogen bonding clusters, the gelation condition and the generalized scaling law can be obtained directly. These results show that such a system can undergo phase transition process. Furthermore, a relationship between Gibbs free energy of forming hydrogen bond and conversions of groups is given. As an example, the chemical shift of OH groups is considered.

Physical Simulation for Large-Bore Copper Vapor Laser
YU De-Li, WANG Run-Wen, TAO Yong-Xiang
Chin. Phys. Lett. 2000, 17 (1): 19-21 .  
Abstract   PDF(pc) (189KB) ( 503 )
On the basis of the electric circuit differential equations and the nonlinear partial differential equations of kinetics, a kinetic model for a series of large-bore copper-vapor lasers is carried out. Through the consistent computational results the radial kinetic parameters such as the stimulating electric field and the plasma electron temperature are presented. The factors, which evidently influence the output power and the beam quality of the large-bore copper-vapor laser, are the buffer gas pressure and the charging voltage.
Electro-optical Properties and Temporal Stability of the Guest-Host DCNP/PEK-c Polymer Thin Film
SHI Wei, FANG Chang-Shui, PAN Qi-Wei, SUN Xun, GU Qing-Tian, XU Dong, WEI Hong-Zhen, YU Jin-Zhong
Chin. Phys. Lett. 2000, 17 (1): 22-24 .  
Abstract   PDF(pc) (331KB) ( 630 )
The polyetherketone (PEK-c) guest-host system thin films in which the range of the weight percent of 3-(1,l-dicyanothenyl)-l-phenyl-4, 5-dihydro-1H-pryazole (DCNP) is from 20% to 50% were prepared. The predicted high value of electro-optical (EO) coefficient γ33 = 48.8pm/V by using two-level model was obtained when the weight percent of DCNP in the polymer system is 40%.whereas EO coefficients are attenuated at higher chromophore loading than 40%. The temporal stability of the EO activity of the guest-host polymer was evaluated by probing the decay of the orientational order of the chromophores in the polymer system.

Spontaneous Emission from a Driven Atom Embedded in a Photonic Crystal
XIE Shuang-Yuan, YANG Ya-Ping, CHENG Hong, ZHU Shi-Yao, WU Xiang
Chin. Phys. Lett. 2000, 17 (1): 25-27 .  
Abstract   PDF(pc) (253KB) ( 369 )
The properties of the spontaneous emission from a three-level atom with an external driving field in a photonic crystal are studied. The population in the two upper levels displays complete decay or oscillatory behavior, depending on the initial atomic state and the relative position of the two upper levels from the forbidden gap. The intensity and the phase of the external field can also affect spontaneous emission from the atom.

Abnormal Shift of Center Wavelength in Annealing Long-Period Gratings
QIN Li, WEI Zhan-Xiong, WANG Qing-Ya, LI Hui-Ping, ZHANG Yu-Shu, GAO Ding-San
Chin. Phys. Lett. 2000, 17 (1): 28-30 .  
Abstract   PDF(pc) (272KB) ( 408 )
During annealing process of long-period gratings, the center wavelengths of some modes shift to red wavelength while those of others shift to blue compared with their original written ones, and the magnitudes of the shifts are related to the decay of the grating strength. The red shifts of center wavelength are more evident in lower-order modes of the gratings. We suggest that part of the photodissociated-H2 combines continuously with Ge-defect centers within 2h after UV-exposure, and with which the observed abnormal shifts can be explained successfully.

Microwave Absorption in Electron Cyclotron Resonance Plasma
LIU Ming-Hai, HU Xi-Wei, WU Qin-Chong, YU Guo-Yang
Chin. Phys. Lett. 2000, 17 (1): 31-33 .  
Abstract   PDF(pc) (232KB) ( 354 )
The microwave power absorption in electron cyclotron resonance plasma reactor was investigated with a two-dimensional hybrid-code. Simulation results indicated that there are two typical power deposition profiles over the entire parameter region: (1) microwave power deposition peaks on the axis and decreases in radial direction, (2) microwave power deposition has its maximum at some radial position, i.e., a hollow distribution. The spatial distribution of electron temperature resembles always to the microwave power absorption profile. The dependence of plasma parameter on the gas pressure is discussed also.

Different Cooling Rate Dependences of Different Microstructure Units in Aluminium Glass by Molecular Dynamics Simulation
LIU Chang-Song, ZHU Zhen-Gang, XIA Jun-Chao, SUN De-Yan
Chin. Phys. Lett. 2000, 17 (1): 34-36 .  
Abstract   PDF(pc) (250KB) ( 419 )
Constant-pressure molecular dynamics simulation and the pair analysis technique have been performed to study the microstructural evolution of aluminium during rapid solidification. The microstructure characteristics of icosahedral ordering increase with decrease of the cooling rate, whereas the microstructure unit characteristics of hcp crystalline structure decrease. There are two kinds of microstructure units which are similar to those in the fcc crystal containing interstitialcies. These two kinds of microscopic units are nearly independent of the cooling rate. The microscopic structural unit characteristics of fcc crystalline structure do not depend on the cooling rate either. These results may help us understand the microstructure of glass and its stability.
Random Neighbor Sandpile Model with Constrained Total Energy
ZHANG Shu-Dong
Chin. Phys. Lett. 2000, 17 (1): 37-39 .  
Abstract   PDF(pc) (244KB) ( 447 )
We propose an energy-constrained sandpile model with random neighbors. The critical behavior of the model is in the same universality class as the mean-field self-organized criticality sandpile. The critical energy Ec depends on the number of neighbors n of each site, but the various exponents do not. For n = 6 , we got that Ec = 0.4545; and a self-similar structure of the energy distribution function with five major peaks is also observed. This is a natural result of system dynamics and the way the system is disturbed.

Splitting Behaviour of Implanted MeV Au+ Ions in LiB3O5
WANG Ke-ming, SHI Bo-rong, Nelson Cue, LU Fei, WANG Feng-xiang, XIE Zhao-xia, SHEN Ding-yu, LIU Yao-gang
Chin. Phys. Lett. 2000, 17 (1): 40-42 .  
Abstract   PDF(pc) (242KB) ( 397 )
The diffusion behaviour of 1.0 and 2.0MeV Au+ implanted into LiB3O5 single crystal has been studied by the Rutherford backscattering of 2.1 MeV He ions. Annealing was performed at temperatures of 600, 700, and 800°C each for 30min. The results show that the diffusion behaviour is quite different in two cases. In LiB3O5, the depth distribution of the 1.0 MeV Au is nearly Gaussian and becomes bimodal after annealing at 800°C for 30min. But in the case of 2.0MeV, the depth distribution of as implanted Au+ in LiB3O5 has splitting behaviour. After 800°C for 30min annealing, there is no obvious diffusion observed. The precise interpretation is needed.

Non-planar and Non-linear Second Sound Waves in He II
ZHANG Peng, KIMURA Seiji, MURAKAMI Masahide, WANG Ru-zhu
Chin. Phys. Lett. 2000, 17 (1): 43-45 .  
Abstract   PDF(pc) (209KB) ( 432 )
Non-planar and non-linear second sound wave are experimentally investigated in an open He II bath. It is found that second sound wave characterized by a negative tail part in an open He II bath is different from that propagating through a channel, and the shape of the negative tail part of second sound wave varies at different location in an open He II bath. Theoretical consideration is also carried out based on two-fluid model and vortex evolution equation. It is found that experimental and theoretical results agree rather well with each other. Second sound wave may develop into the thermal shock wave provided that the heat flux is large.

Sign Change of Thermopower at Low Temperatures in Nd0.7 ( Ca,Sr,Ba)0.3 MnO3
ZHOU Sheng-Ming, DONG Qiu-Zhao, ZHOU Gui-En, ZHANG Yu-Heng
Chin. Phys. Lett. 2000, 17 (1): 46-48 .  
Abstract   PDF(pc) (284KB) ( 462 )
The temperature dependence of thermopower and resistivity for the series of Nd0.7 ( Ca,Sr,Ba)0.3 MnO3with a fixed average A-site cation radius have been measured. Infrared spectra revealed that the size differences between various A-site ions cause large local distortions of MnO6 octahedra. The thermopower is enhanced above metal-insulator transition temperature Tm and is reduced below Tm by increasing amount of A-site cation disorder. The sign change of thermopower induced by A-site cation disorder has been observed at low temperatures. The observed thermopower behaviors have been explained by Mott's formula and the effect of the spin disorder scattering.

Surface Alloying of Submonolayer Pb on Cu(ll1) Studied by Photoemission
XU Ming-Chun, QIAN Hai-Jie, LIU Feng-Qin, KRASH Ibrahim, LA Wu-Yan, WU Si-Cheng
Chin. Phys. Lett. 2000, 17 (1): 49-51 .  
Abstract   PDF(pc) (312KB) ( 428 )
The reactions of superthin Pb films on a Cu (111) surface with respect to the coverage of Pb and annealing have been studied by synchrotron radiation photoemission. The submonolayer Pb atoms deposited at room temperature are distributed on the Cu (111) surface as two-dimensional (2D) islands. Annealing to 200oC gives rise to Pb-Cu surface alloy formation. Analyses show that the surface alloy occurs only in the first layer of the Cu (111) surface. As a surfactant, Pb can promote 2D layer-by-layer growth of thin films on Cu (111), but the
Pb-Cu surface alloying may have an unfavorable effect on the activation process.

Formation of Multi-branched Domains in Magnetic Garnet Bubble Films
ZHOU Yan, ZHENG De-Juan, LI Dan, HAN Bao-Shan
Chin. Phys. Lett. 2000, 17 (1): 52-54 .  
Abstract   PDF(pc) (281KB) ( 344 )
A “low-bias-field method” for the formation of multi-branched domains (MBD’s) in garnet bubble films has been introduced. By using this method, only a single MBD can be formed each time inside a pancake coil with an inner diameter of 1 mm. The formation of MBD's is associated with the nucleation of vertical-Bloch-lines in their walls. Therefore, with the decrease of the bias field Hb from the “critical static bias field for multi-branched expansion” H[d], the patterns of MBD’s become more and more complex, accompanying with the successive formation of three types of hard domains. The typical photos and the static properties of MBD’s are presented.

Critical Point of Ising Films with Different Growth Directions
WANG Huai-yu, ZHOU Yun-song, D.L.Lin
Chin. Phys. Lett. 2000, 17 (1): 55-57 .  
Abstract   PDF(pc) (222KB) ( 406 )
The critical temperature Tc of a spin-1/2 Ising film of cubic structures is calculated by the variational cumulant expansion method for three directions of growth. The results from different growth directions are analysed and compared with each other. In the present model, the Tc values depend largely on the number of nearest neighbors in a monolayer for films with the same number of monolayers but grown in different directions. For sc, bcc and fcc structures, the highest Tc is found along the (100), (110), and (111) direction, respectively.

A Novel Oligomer Poly (Phenylene Vinylene) Derivative Containing Oxadiazole Segment
YANG Xiao-Hui, YIN Shou-Gen, WANG Zhen-Jia, HOU Yan-Bing, XU Zheng, XU Xu-Rong, PENG Jun-Biao, LI Wen-Lian
Chin. Phys. Lett. 2000, 17 (1): 58-60 .  
Abstract   PDF(pc) (271KB) ( 335 )
A novel oligomer PPV derivative (OPPV) is reported, which is designed to contain the oxadiazole function segment in the main chain. Photoluminescence of the OPPV thin film originates from aggregated states. In a double layer device consisting of poly phenylene vinylene (PPV) and OPPV, emission only from PPV layer was observed and the efficiency of the device was improved by about one order of magnitude compared with the single layer PPV device, this indicates the electron transport characteristic of OPPV. In the OPPV/Tb complex device, OPPV functions as the hole transport layer. A possible explanation is proposed.

Influence of Low-Energy Ion Irradiation on Plasma Membrane Permeability of Cells
ZHANG Dong-Mei, CUI Fu-Zhai, SUN Su-Qin, LIN You-Bo, TIAN Min Bo, CHEN Guo-Qiang
Chin. Phys. Lett. 2000, 17 (1): 61-63 .  
Abstract   PDF(pc) (308KB) ( 460 )
Effect of low-energy ion irradiation on plasma membrane permeability has been investigated by using electron spin resonance (ESR) spectroscopy of spin probe technique. The investigated system is plumule cells of wheat (Tkiticum aestivum L.) seeds implanted by 30keV N+ ions. ESR spectra indicated that plasmalemma permeability is sensitive to low-energy ion irradiation. Ion irradiations with increasing fluences up to semi-lethal dose lead to gradual increase in plasmalemma permeability of the plumule cells. The possible factors relevant to the changes in membrane permeability are discussed in relation to the changes in the physical state and chemical nature of membranes.

Implementation of Quantum Logic Gates by Nuclear Magnetic Resonance Spectroscopy
DU Jiang-Feng, WU Ji-Hui, SHI Ming-Jun, HAN Liang, ZHOU Xian-Yi, , YE Bang-Jiao, WENG Hui-Ming, HAN Rong-Dian,
Chin. Phys. Lett. 2000, 17 (1): 64-66 .  
Abstract   PDF(pc) (232KB) ( 390 )
Using nuclear magnetic resonance techniques with a solution of cytosine molecules, we show an implementation of certain quantum logic gates (including NOT gate, square-root of NOT gate and controlled-NOT gate), which have central importance in quantum computing. In addition, experimental results show that nuclear magnetic resonance spectroscopy can efficiently measure the result of quantum computing without attendant wave-function collapse.

Temperature Rise at the Edges of Dark Molecular Clouds
MAO Xin-Jie
Chin. Phys. Lett. 2000, 17 (1): 67-69 .  
Abstract   PDF(pc) (216KB) ( 359 )
Two-fluid magnetohydrodynamic equations are applied to dark molecular clouds that are composed of neutrals mixed with minor charged particles, weakly ionized gas systems. The result shows the temperatures are higher at the cloud edges than at their inner regions, the cause of which is that the cloud potential, released as clouds contract particularly at their edges, along with some dissipated rotational kinetic energy is converted into thermal. The cloud contracting is due to the loss of the magnetic field that threads it through ambipolar diffusion. Nevertheless, without the support of the magnetic and the centrifugal forces in the direction of the magnetic field assumed to be parallel to the cloud rotating axis, the cloud collapses in that direction when its mass is over the Jeans mass.
Dependence of Spiral Galaxy Distribution on Viewing Angle in RC3
MA Jun, SONG Guo-Xuan, SHU Cheng-Gang
Chin. Phys. Lett. 2000, 17 (1): 70-72 .  
Abstract   PDF(pc) (238KB) ( 447 )
The normalized inclination distributions are presented for the spiral galaxies in RC3. The results show that, except for the bin of 8l°-90°, in which the apparent minor isophotal diameters that are used to obtain the inclinations are affected by the central bulges, the distributions for Sa, Sab, Scd and Sd are well consistent with the Monte-Carlo simulation of random inclinations within 3-σ, and Sb and Sbc almost, but Sc is different. One reason for the difference between the real distribution and the Monte-Carlo simulation of Sc may be that some quite inclined spirals, the arms of which are inherently loosely wound on the galactic plane and should be classified to Sc galaxies, have been incorrectly classified to the earlier ones, because the tightness of spiral arms which is one of the criteria of the Hubble classification in RC3 is different between on the galactic plane and on the tangent plane of the celestial sphere. Our result also implies that there might exist biases in the luminosity functions of individual Hubble types if spiral galaxies are only classified visually.

Trainsient Accretion Disk and Energy Mechanism of Gamma Ray Bursts
LU Ye, ZHENG Guang-Sheng(K. S. Cheng), ZHAO Gang, YANG Lan-Tian
Chin. Phys. Lett. 2000, 17 (1): 73-75 .  
Abstract   PDF(pc) (298KB) ( 499 )
We suggest that a rotating massive black hole (l06 M O) located at an inactive galaxy may convert its host into a transient active phase by capturing and disrupting a star. During this period, a transient accretion disk is formed and a strong transient magnetic field can be produced in the inner boundary of the accretion disk. A large amount of rotational energy of the black hole is extracted and released in the ultra relativistic jet with a bulk Lorentz factor larger than l03 via Blandford-Znajek process. The relativistic jet energy can be converted into γ-ray radiation in the shock region located at a distance of about 1.4 x 1016 cm via the external shock mechanism. The observed properties of GRB971214 is used to illustrate our model.

Origin of the Negative Pressure for Relativistic Boson Condensate
Chin. Phys. Lett. 2000, 17 (1): 76-78 .  
Abstract   PDF(pc) (279KB) ( 604 )
We study the physical origin of the negative pressure for quantum scalar fields in inflationary models. The vacuum state and other quantum coherent states are explicitly constructed for the charged and uncharged relativistic boson condensates, in which the pressure takes negative values.
26 articles