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CN 11-5639/O4
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Chin. Phys. B  
  Chin. Phys. B--2005, Vol.14, No.9
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GENERAL

An extended functional transformation method and its application in some evolution equations

Ding Hai-Yong, Xu Xi-Xiang, Yang Hong-Xiang
Chin. Phys., 2005, 14 (9): 1687-1690 doi: 10.1088/1009-1963/14/9/001
Full Text: [PDF 218 KB] (Downloads:614)
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In this paper, an extended functional transformation is given to solve some nonlinear evolution equations. This function, in fact,is a solution of the famous KdV equation, so this transformation gives a transformation between KdV equation and other soliton equations. Then many new exact solutions can be given by virtue of the solutions of KdV equation.

A method of moments for calculating dynamic responses beyond linear response theory

Kang Yan-Mei, Xu Jian-Xue, Xie Yong
Chin. Phys., 2005, 14 (9): 1691-1697 doi: 10.1088/1009-1963/14/9/002
Full Text: [PDF 288 KB] (Downloads:576)
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A method of moments for calculating the dynamic response of periodically driven overdamped nonlinear stochastic systems in the general response sense is proposed, which is a modification of the method of moments confined within linear response theory. The calculating experience suggests that the proposed technique is simple and efficient in implementation, and the comparison with stochastic simulation shows that the first three orders of susceptibilities calculated by the proposed technique have high accuracy. The dependence of the spectral amplification parameters at the first three harmonics on the noise intensity is also investigated, and another observed phenomenon of stochastic resonance in the systems induced by the location of a single periodic orbit is disclosed and explained.

Applications of F-expansion method to the coupled KdV system

Li Bao-An, Wang Ming-Liang
Chin. Phys., 2005, 14 (9): 1698-1706 doi: 10.1088/1009-1963/14/9/003
Full Text: [PDF 247 KB] (Downloads:730)
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An extended F-expansion method for finding periodic wave solutions of nonlinear evolution equations in mathematical physics is presented, which can be thought of as a concentration of extended Jacobi elliptic function expansion method proposed more recently. By using the homogeneous balance principle and the extended F-expansion, more periodic wave solutions expressed by Jacobi elliptic functions for the coupled KdV equations are derived. In the limit cases, the solitary wave solutions and the other type of travelling wave solutions for the system are also obtained.

Integrals of generalized Hamilton systems with additional terms

Shang Mei, Mei Feng-Xiang
Chin. Phys., 2005, 14 (9): 1707-1709 doi: 10.1088/1009-1963/14/9/004
Full Text: [PDF 185 KB] (Downloads:516)
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Exact travelling wave solutions for (1+1)-dimensional dispersive long wave equation

Liu Cheng-Shi
Chin. Phys., 2005, 14 (9): 1710-1715 doi: 10.1088/1009-1963/14/9/005
Full Text: [PDF 231 KB] (Downloads:1054)
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A complete discrimination system for the fourth order polynomial is given.As an application, we have reduced a (1+1)-dimensional dispersive long wave equation with general coefficients to an elementary integral form and obtained its all possible exact travelling wave solutions including rational function type solutions, solitary wave solutions, triangle function type periodic solutions and Jacobian elliptic functions double periodic solutions. This method can be also applied to many other similar problems.

Probabilistic and controlled teleportation of tripartite state in a general form and its quantum networks

Yuan Hong-Chun, Qi Kai-Guo
Chin. Phys., 2005, 14 (9): 1716-1723 doi: 10.1088/1009-1963/14/9/006
Full Text: [PDF 316 KB] (Downloads:637)
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We discuss a scheme for probabilistic and controlled teleportation of an unknown arbitrary three-particle state by constructing a peculiar non-maximally entangled state as a controlled quantum channel,which is teleported between two sides with the help of the auxiliary particle and the cooperation of the third side (Charlie) as a supervisor. In comparison with some existing schemes, on the receiver's side it is easy to have the sender's state through operating two uniform unitary transformations in turn. In addition, we also give an efficient quantum network for implementing the new scheme by means of some primitive operations.

Probabilistic teleportation of an arbitrary three-particle state

Lin Xiu, Li Hong-Cai
Chin. Phys., 2005, 14 (9): 1724-1731 doi: 10.1088/1009-1963/14/9/007
Full Text: [PDF 218 KB] (Downloads:575)
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A scheme for teleporting an arbitrary and unknown three-particle state from a sender to either one of two receivers is proposed. The quantum channel is composed of a two-particle non-maximally entangled state and two three-particle non-maximally entangled W states. An arbitrary three-particle state can be perfectly teleported probabilistically if the sender performs three generalized Bell-state measurements and sends to the two receivers the classical result of these measurements, and either one of the two receivers adopts an appropriate unitary transformation conditioned on the suitable measurement outcomes of the other receiver. All kinds of unitary transformations are given in detail.

Probabilistic remote preparation of a two-atom entangled state

Zhang Ying-Qiao, Jin Xing-Ri, Zhang Shou
Chin. Phys., 2005, 14 (9): 1732-1735 doi: 10.1088/1009-1963/14/9/008
Full Text: [PDF 189 KB] (Downloads:508)
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A scheme for remotely preparing a two-atom entangled state via entanglement swapping in cavity quantum electronic dynamics (QED) with the help of separate measurements is proposed. And the effect of cavity decay is eliminated in our scheme.

Quantum radiation of non-stationary Kerr-Newman-de Sitter black hole

Jiang Qing-Quan, Yang Shu-Zheng, Li Hui-Ling
Chin. Phys., 2005, 14 (9): 1736-1744 doi: 10.1088/1009-1963/14/9/009
Full Text: [PDF 284 KB] (Downloads:680)
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By introducing a new tortoise coordinate transformation, we investigate the quantum thermal and non-thermal radiations of a non-stationary Kerr--Newman--de Sitter black hole. The accurate location and radiate temperature of the event horizon as well as the maximum energy of the non-thermal radiation are derived. It is shown that the radiate temperature and the maximum energy are related to not only the evaporation rate, but also the shape of the event horizon, moreover the maximum energy depends on the electromagnetic potential. Finally, we use the results to reduce the non-stationary Kerr--Newman black hole, the non-stationary Kerr black hole, the stationary Kerr--Newman--de Sitter black hole, and the static Schwarzshild black hole.

Symmetric linear potential and imperfect Brownian ratchet in molecular motor function

Li Fang-Zhen, Hu Kuang-Hu, Su Wan-Fang, Chen Yi-Chen
Chin. Phys., 2005, 14 (9): 1745-1754 doi: 10.1088/1009-1963/14/9/010
Full Text: [PDF 285 KB] (Downloads:420)
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Biomolecular motors are tiny engines that transport materials at the microscopic level within biological cells. In recent years, Elston and Peskin et al have investigated the effect of the elastic properties of the tether that connects the motor to its cargo at the speed of the motor. In this paper we extend their work and present a tether in the form of symmetric linear potential.Our results show that when the driving mechanism is an imperfect Brownian ratchet, the average speed decreases as the stiffness of the tether increases in the limit of large motor diffusion coefficient, which is similar to the results of Elston and Peskin.However, a threshold for the stiffness of the tether connecting the motor to its cargo is found in our model. Only when the tether is stiffer than the threshold can the motor and its cargo function co-operatively, otherwise, the motor and its cargo depart from each other. This result is more realistic than that of the spring model of Elston and Peskin.

Adaptive synchronization of a critical chaotic system

Tu Li-Lan, Lu Jun-An
Chin. Phys., 2005, 14 (9): 1755-1759 doi: 10.1088/1009-1963/14/9/011
Full Text: [PDF 239 KB] (Downloads:567)
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This paper further investigates the synchronization problem of a new chaotic system with known or unknown system parameters. Based on the Lyapunov stability theory, a novel adaptive control law is derived for the synchronization of a new chaotic system with known or unknown system parameters. Theoretical analysis and numerical simulations show the effectiveness and feasibility of the proposed schemes.

Controlling and synchronizing spatiotemporal chaos of the coupled Bragg acousto-optical bistable map system using nonlinear feedback

Yue Li-Juan, Shen Ke
Chin. Phys., 2005, 14 (9): 1760-1765 doi: 10.1088/1009-1963/14/9/012
Full Text: [PDF 2855 KB] (Downloads:3380)
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In this paper we present the control and synchronization of a coupled Bragg acousto-optic bistable map system using nonlinear feedback technology. This nonlinear feedback technology is useful to control a temporally chaotic system as well as a spatiotemporally chaotic system. It can be extended to synchronize the spatiotemporal chaos. It can work in a wide range of the controlled and synchronized signals, so it can decrease the sensitivity down to a noise level. The synchronization can be obtained by the analysis of the largest conditional Lyapunov exponent spectrum, and easily implemented in practical systems just by adjusting the coupled strength without any pre-knowledge of the dynamic system required.

Upper bound for the time derivative of entropy for a dynamical system driven by coloured cross-correlated white noises

Xie Wen-Xian, Xu Wei, Cai Li, Jin Yan-Fei
Chin. Phys., 2005, 14 (9): 1766-1769 doi: 10.1088/1009-1963/14/9/013
Full Text: [PDF 224 KB] (Downloads:506)
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It is shown how the cross-correlation time and strength of coloured cross-correlated white noises can set an upper bound for the time derivative of entropy in a nonequilibrium system. The value of upper bound can be calculated directly based on the Schwartz inequality principle and the Fokker--Planck equation of the dynamical system driven by coloured cross-correlated white noises. The present calculations can be used to interpret the interplay of the dissipative constant and cross-correlation time and strength of coloured cross-correlated white noises on the upper bound.

Effects of high pressure on the Raman and fluorescence emission spectra of two novel 1,3,4-oxadiazole derivatives

Luo Ji-Feng, Tang Ben-Chen, Gao Chun-Xiao, Li Min, Han Yong-Hao, Zou Guang-Tian
Chin. Phys., 2005, 14 (9): 1770-1773 doi: 10.1088/1009-1963/14/9/014
Full Text: [PDF 279 KB] (Downloads:470)
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The effects of pressure on the fluorescence emission and Raman spectra of 1,4-bis[(4-methyloxyphenyl)-1,3,4-oxadiazolyl]- 2,5-bisheptyloxyphenylene (OXD-2) and on the fluorescence emission spectra of 1,4-bis[(4-methylphenyl)-1,3,4-oxadiazolyl]phenylene (OXD-1) are investigated using a diamond anvil cell. With the increase of pressure, the intensity of the fluorescence emission increases and reaches maxima at 13GPa for OXD-1 and at 9.6GPa for OXD-2. The effect of pressure on the peak position of the emission shows a similar trend, red shift with the increase of pressure. But at higher pressures, the intensity of emission drops down dramatically. The Raman spectra of OXD-2 indicate that there appears a structural change at ca 3GPa.

Effect of temperature on the morphology of nanobubbles at mica/water interface

Zhang Xue-Hua, Li Gang, Wu Zhi-Hua, Zhang Xiao-Dong, Hu Jun
Chin. Phys., 2005, 14 (9): 1774-1778 doi: 10.1088/1009-1963/14/9/015
Full Text: [PDF 747 KB] (Downloads:726)
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The great implication of nanobubbles at a solid/water interface has drawn wide attention of the scientific community and industries. However, the fundamental properties of nanobubbles remain unknown as yet. In this paper, the temperature effects on the morphology of nanobubbles at the mica/water interface are explored through the combination of AFM direct image with the temperature control. The results demonstrate that the apparent height of nanobubbles in AFM images is kept almost constant with the increase of temperature, whilst the lateral size of nanobubbles changes significantly. As the temperature increases from 28{^\circ}C to 42{^\circ}C, the lateral size of nanobubbles increases, reaching a maximum at about 37{^\circ}C, and then decreases at a higher temperature. The possible explanation for the size change of nanobubbles with temperature is suggested.
RAPID COMMUNICATION

Nonlinear optical properties of Au/PVP composite thin films

Shen Hong, Cheng Bo-Lin, Lü Guo-Wei, Wang Wei-Tian, Guan Dong-Yi, Chen Zheng-Hao, Yang Guo-Zhen
Chin. Phys., 2005, 14 (9): 1915-1918 doi: 10.1088/1009-1963/14/9/042
Full Text: [PDF 649 KB] (Downloads:636)
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Colloidal Au and poly(vinylpyrrolidone) (PVP) composite thin films are fabricated by spin-coating method. Linear optical absorption measurements of the Au/PVP composite films indicate an absorption peak around 530 nm due to the surface plasmon resonance of gold nanoparticles. Nonlinear optical properties are studied using standard Z-scan technique, and experimental results show large optical nonlinearities of the Au/PVP composite films. A large value of \chi3 / \alpha up to 0.56×10-10esu?cm is obtained, which is comparable to the best values reported in metal/oxide composite films.
NUCLEAR PHYSICS

Velvet's multi-pulsed emission and multi-pulsed electron beams

Xia Lian-Sheng, Zhang Huang, Chen De-Biao, Zhang Kai-Zhi, Shi Jin-Shui, Zhang Lin-Wen
Chin. Phys., 2005, 14 (9): 1779-1783 doi: 10.1088/1009-1963/14/9/016
Full Text: [PDF 1077 KB] (Downloads:536)
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The velvet electron emission characteristics and beams' brightness are investigated with a multi-pulsed mode. The results indicate that in the multi-pulsed mode the velvet emission is not uniform and the periphery emission is much stronger than that from the centre. The periphery emission contributes much more to the formation of the cathode plasma than the centre emission, which leads to diode impendence breakdown. The relationship between the cathode plasma expansion and the initial emittance of the cathode is deduced to describe the characteristics of the multi-pulsed vacuum diode. The emittance of the multi-pulsed beams is measured to be less than 1000mm \cdot mrad. The brightness of the electron beams is better than 1\times 10^{8}A/(m \cdot rad)^{2}.
CLASSICAL AREAS OF PHENOMENOLOGY

Theoretical and experimental study of the intensity distribution in biological tissues

Xu Tang, Zhang Chun-Ping, Chen Gui-Ying, Tian Jian-Guo, Zhang Guang-Yin, Zhao Cheng-Mei
Chin. Phys., 2005, 14 (9): 1813-1820 doi: 10.1088/1009-1963/14/9/022
Full Text: [PDF 350 KB] (Downloads:587)
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Based on the diffusion approximate theory (DA), a theoretical model about the distribution of the intensity of a narrow collimation beam illuminating on a semi-infinite biological tissue is developed. In order to verify the correctness of the model, a novel method of measuring the distributions of the intensity of light in Intralipid-10% suspension at 650 nm is presented and measurements of the distributions of the distance-dependent intensity of scattering light in different directions are made. The investigations show that the results from our diffusion model are in good agreement with the experimental results beyond and in the areas around the light source, and the distance-dependent intensity in the incident direction attenuates approximately in the exponential form. Furthermore, our theoretic results indicate the anisotropic characteristics of the intensity in different directions of scattering light inside the biological tissue.

Scheme for implementing quantum secret sharing via cavity QED

Chen Zhi-Hua, Lin Xiu-Min
Chin. Phys., 2005, 14 (9): 1821-1824 doi: 10.1088/1009-1963/14/9/023
Full Text: [PDF 237 KB] (Downloads:533)
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An experimentally feasible scheme for implementing quantum secret sharing via cavity quantum electrodynamics (QED) is proposed. The scheme requires the large detuning of the cavity field from the atomic transition, the cavity is only virtually excited, thus the requirement on the quality factor of the cavity is greatly loosened.

Teleportation of atomic states with a weak coherent cavity field

Zheng Shi-Biao
Chin. Phys., 2005, 14 (9): 1825-1827 doi: 10.1088/1009-1963/14/9/024
Full Text: [PDF 179 KB] (Downloads:490)
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A scheme is proposed for the teleportation of an unknown atomic state. The scheme is based on the resonant interaction of atoms with a coherent cavity field. The mean photon-number of the cavity field is much smaller than one and thus the cavity decay can be effectively suppressed. Another advantage of the scheme is that only one cavity is required.

Higher-order squeezing of quantum field and higher-order uncertainty relations in non-degenerate four-wave mixing

Li Xi-Zeng, Su Bao-Xia, Chai Lu
Chin. Phys., 2005, 14 (9): 1828-1833 doi: 10.1088/1009-1963/14/9/025
Full Text: [PDF 276 KB] (Downloads:759)
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It is found that the field of the combined mode of the probe wave and the phase conjugate wave in the process of non-degenerate four-wave mixing exhibits higher-order squeezing to all even orders. The higher-order squeezed parameter and squeezed limit due to the modulation frequency are investigated. The smaller the modulation frequency is, the stronger the degree of higher-order squeezing becomes. Furthermore, the higher-order uncertainty relations in the process of non-degenerate four-wave mixing are presented for the first time. The product of higher-order noise moments is related to even order number N and the length L of the medium.

Optical bistability of a composite system induced by a broadband squeezed vacuum

Luo Jin-Ming, Li Jia-Hua
Chin. Phys., 2005, 14 (9): 1834-1838 doi: 10.1088/1009-1963/14/9/026
Full Text: [PDF 254 KB] (Downloads:487)
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A composite system consisting of a degenerate optical parametric oscillator (DOPO) and N two-level atoms interacting with a broadband squeezed vacuum (SV) centred at frequency \omega_{\rm s} and an input monochromatic pumping field with a frequency \omega_{\rm p} is analysed. The corresponding explicit analytical steady-state solutions in the central mode \omega_{\rm p}=\omega_{\rm s} are derived, and the result displays optical bistability (OB). In addition, the influence of the broadband SV on the bistable behaviour is analysed in detail.

Bound soliton pulses in a passively mode-locked fibre ring laser

Zhang Shu-Min, Lü Fu-Yun, Gong Yan-Dong, Zhou Xiao-Qun, Yang Xiu-Feng, Lü Chao
Chin. Phys., 2005, 14 (9): 1839-1843 doi: 10.1088/1009-1963/14/9/027
Full Text: [PDF 974 KB] (Downloads:434)
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The bound solitons in a passively mode-locked fibre ring laser are observed and their formation mechanism is summarized in this paper. In order to obtain stable bound solitons, a strong CW laser field at the centre of the soliton spectral is necessary to suppress and synchronize the random soliton phase variations.

Effects of container geometry on granular segregation pattern

Hu Mao-Bin, Kong Xiang-Zhao, Wu Qing-Song, Wu Yong-Hong
Chin. Phys., 2005, 14 (9): 1844-1849 doi: 10.1088/1009-1963/14/9/028
Full Text: [PDF 1554 KB] (Downloads:459)
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In a set of vibrating quasi-two-dimensional containers with the right-hand sidewall bent inward, three new segregation patterns have been identified experimentally including a Two-Side segregation Pattern, a Left-hand Side segregation Pattern and a pattern where big particles aggregate to the upper left part of the container. In a container with small bending degree, either the two-side segregation pattern or the left-hand side segregation pattern is stable, which is determined by the initial distribution of particles.
ATOMIC AND MOLECULAR PHYSICS

Conditional stability of diatomic molecule driven by a weak laser field

Chong Gui-Shu, Hai Wen-Hua, Xie Qiong-Tao
Chin. Phys., 2005, 14 (9): 1784-1791 doi: 10.1088/1009-1963/14/9/017
Full Text: [PDF 290 KB] (Downloads:406)
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Using a direct perturbation method, we investigate the stability of a diatomic molecule modelled by a weakly laser-driven Morse oscillator. It is shown that stationary state solution of the system is stable in the sense of Lyapunov and the periodical one possesses conditional stability, namely its stability depends on the initial conditions and system parameters. The corresponding sufficient and necessary conditions are established that indicate the stable states associated with some discrete energies. The results reveal how a diatomic molecule can be stabilized or dissociated with a weak laser, and demonstrate that the mathematical conditional stability works in the considered physical system.

Theoretical studies on the photoionization cross-sections of solid silver

Ma Xiao-Guang, Sun Wei-Guo
Chin. Phys., 2005, 14 (9): 1792-1798 doi: 10.1088/1009-1963/14/9/018
Full Text: [PDF 857 KB] (Downloads:471)
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An alternative expression for photoionization cross-section of atoms or molecules and a dielectric influence function (DIF) in a high-density system proposed recently are used to study the photoionization cross-sections of solid silver. It is suggested that a density turning point (DTP) of a photoionized system may be viewed as the critical point where the photoionization properties of atoms in a real system may have a notable change. The results show that the present theoretical photoionization cross-sections are in good agreement with the experimental results of a silver crystal both in structure and in magnitude.

Nanocrystal formation and structure in oxyfluoride glass ceramics

Yu Hua, Zhao Li-Juan, Meng Jie, Liang Qin, Yu Xuan-Yi, Tang Bai-Quan, Xu Jing-Jun
Chin. Phys., 2005, 14 (9): 1799-1802 doi: 10.1088/1009-1963/14/9/019
Full Text: [PDF 462 KB] (Downloads:476)
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The up-conversion luminescent property of the oxyfluoride glass ceramics 30SiO_{2}\cdot15Al_{2}O_{3}\cdot (50--x)PbF_{2}\cdot xCdF_{2} doped with 4ErF_{3}\cdot1YbF_{3} has been investigated. Up-conversion luminescent intensity of Er^{3+} ions increased obviously after heat-treatment due to co-doping with CdF_{2}. The structure model of nanocrystals Pb_{x}Cd_{1-x}F_{2} was determined and the effect of CdF_{2} in oxyfluoride glass ceramics was explained by the analysis of x-ray diffraction data. Different nucleation temperatures of samples with different compositions were obtained by differential thermal analysis curves and the results showed the growth process of different nanocrystals in glass ceramics.

Ion source effect on the bond length of 4HeH+

Miao Jing-Wei, Wang Hu, Zhu Zhou-Sen, Yang Chao-Wen, Shi Mian-Gong, Tang A-You, Miao Lei, Xu Zu-Run, Yuan Xue-Dong, Liu Xiao-Dong, Yang Bei-Fang
Chin. Phys., 2005, 14 (9): 1803-1807 doi: 10.1088/1009-1963/14/9/020
Full Text: [PDF 274 KB] (Downloads:394)
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The bond length of ^{4}HeH^{+} resulting from collision-induced destruction is measured at 1.4420 MeV using the Coulomb Explosion Technique. The measured bond length of ^4HeH^+ is 0.094\pm 0.003nm. The bond length of ^{4}HeH^{+} obtained with our radio frequency (RF) ion source is larger than that obtained with a duoplasmatron ion source at Argonne National Laboratory (ANL), but the bond lengths of H_{2}^{+} and H_{3}^{+}obtained separately by ANL and by us with the two different ion sources are consistent with each other, which implies that there exists an ion source effect on the bond length of ^{4}HeH^{+}. The main reason why the ^{4}HeH^{+} bond lengths obtained by the two different ion sources are different is also discussed.

Spin polarization effect for Os2 molecule

Xie An-Dong, Yan Shi-Ying, Zhu Zheng-He, Fu Yi-Bei
Chin. Phys., 2005, 14 (9): 1808-1812 doi: 10.1088/1009-1963/14/9/021
Full Text: [PDF 265 KB] (Downloads:724)
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Density functional Theory (DFT) (B3p86) of Gaussian03 has been used to optimize the structure of Os$_2$ molecule. The result shows that the ground state for Os$_2$ molecule is 9-multiple state and its electronic configuration is $^{9}\Sigma _{\rm g}^{+}$, which shows spin polarization effect of Os$_2$ molecule of transition metal elements for the first time. Meanwhile, we have not found any spin pollution because the wavefunction of the ground state does not mingle with wavefunctions with higher energy states. So, the fact that the ground state for Os$_2$ molecule is a 9-multiple state is indicative of spin polarization effect of Os$_2$ molecule of transition metal elements. That is, there exist 8 parallel spin electrons. The non-conjugated electron is greatest in number. These electrons occupy different spacious tracks, so that the energy of Os$_2$ molecule is minimized. It can be concluded that the effect of parallel spin of Os$_2$ molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell--Sorbie potential functions with the parameters for the ground state $^{9}\Sigma _{\rm g}^{+}$ and other states of Os$_2$ molecule are derived. Dissociation energy $D_\e$ for the ground state of Os$_2$ molecule is 3.3971eV, equilibrium bond length Re is 0.2403nm, vibration frequency $\omega _\e $ is 235.32cm$^{-1}$. Its force constants $f_2$, $f_3$, and $f_4$ are 3.1032$\times $10$^{2}$aJ$\cdot$nm$^{-2}$, $-14.3425\times $10$^{3}$aJ$\cdot$nm$^{-3}$ and 50.5792$\times $10$^{4}$aJ$\cdot$nm$^{-4 }$ respectively. The other spectroscopic data for the ground state of Os$_2$ molecule $\omega_{\e}\chi_{\e}$, $B_{\e}$ and $\alpha_{\e}$ are 0.4277cm$^{-1}$, 0.0307cm$^{-1}$ and 0.6491$\times $ 10$^{-4}$cm$^{-1}$ respectively.
CROSS DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

Floating zone growth and magnetic and specific heat properties of La0.67Ca0.33Mn1-xFexO3 (x=0.00, 0.04) single crystals

Kou Zhi-Qi, Ma Xiao, Di Nai-Li, Li Qing-An, Cheng Zhao-Hua
Chin. Phys., 2005, 14 (9): 1896-1899 doi: 10.1088/1009-1963/14/9/038
Full Text: [PDF 783 KB] (Downloads:329)
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Single crystals of La0.67Ca0.33MnO3 and La0.67Ca0.33Mn0.96Fe0.04O3 were obtained by floating zone method. Laue diffraction pattern and rocking curve of the single crystals show that their quality is good. The magnetic behaviours of these compounds have been studied. Fe doping significantly depresses the magnetic contribution to the total specific heat CP, but slightly influences the lattice contribution at temperatures above 50K. The peak of CP shifts towards high temperatures with increasing magnetic field. Both single crystals exhibit the first-order magnetic transition around the Curie temperature.

Theoretical analysis of nanosecond crystallization kinetics of phase-change optical recording films

Zhang Xue-Ru, Yang Kun, Song Ying-Lin
Chin. Phys., 2005, 14 (9): 1900-1903 doi: 10.1088/1009-1963/14/9/039
Full Text: [PDF 215 KB] (Downloads:377)
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A theoretical investigation of nanosecond crystallization kinetics of the phase-change optical recording films is presented. An extended Kissinger equation for the square-root heating is derived, which properly describes the temperature evolution of the films by nanosecond laser heating. The extended Kissinger equation was used to explain our previous experimental results.

Influence of laser intensity in second-harmonic detection with tunable diode laser multi-pass absorption spectroscopy

Kan Rui-Feng, Dong Feng-Zhong, Zhang Yu-Jun, Liu Jian-Guo, Liu Cheng, Wang Min, Gao Shan-Hu, Chen Jun
Chin. Phys., 2005, 14 (9): 1904-1909 doi: 10.1088/1009-1963/14/9/040
Full Text: [PDF 275 KB] (Downloads:610)
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Tunable diode laser absorption spectroscopy (TDLAS) has been widely employed in atmospheric trace gases detection. The ratio of the second-harmonic signal to the intensity of laser beam incident to the multi-pass cell is proved to be proportional to the product of the path length and the gas concentration under any condition. A new calibration method based on this relation in TDLAS system for the measurement of trace gas concentration is proposed for the first time. The detection limit and the sensitivity of the system are below 110 and 31ppbv (parts-per-billion in volume), respectively.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

Few-cycle relativistic solitons in plasmas

Fang Zong-Bao, Shen Bai-Fei, Cheng Chun-Fu, Zhang Xiao-Mei
Chin. Phys., 2005, 14 (9): 1850-1855 doi: 10.1088/1009-1963/14/9/029
Full Text: [PDF 256 KB] (Downloads:486)
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A set of exact one-dimensional solutions to coupled nonlinear equations describing the propagation of a relativistic ultrashort circularly polarized laser pulse in a cold collisionless and bounded plasma where electrons have an initial velocity in the laser propagating direction is presented. The solutions investigated here are in the form of quickly moving envelop solitons at a propagation velocity comparable to the light speed. The features of solitons in both underdense and overdense plasmas with electrons having different given initial velocities in the laser propagating direction are described. It is found that the amplitude of solitons is larger and soliton width shorter in plasmas where electrons have a larger initial velocity. In overdense plasmas, soliton duration is shorter, the amplitude higher than that in underdense plasmas where electrons have the same initial velocity.

Effects of drive current rise-time and initial load density distribution on Z-pinch characteristics

Duan Yao-Yong, Guo Yong-Hui, Wang Wen-Sheng, Qiu Ai-Ci
Chin. Phys., 2005, 14 (9): 1856-1861 doi: 10.1088/1009-1963/14/9/030
Full Text: [PDF 383 KB] (Downloads:535)
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A two-dimensional, three-temperature radiation magneto-hydrodynamics model is applied to the investigation of evolutional trends in x-ray radiation power, energy, peak plasma temperature and density as functions of drive current rise-time and initial load density distribution by using the typical experimental parameters of tungsten wire-array Z-pinch on the Qiangguang-I generator. The numerical results show that as the drive current rise-time is shortened, x-ray radiation peak power, energy, peak plasma density and peak ion temperature increase approximately linearly, but among them the x-ray radiation peak power increases more quickly. As the initial plasma density distribution in the radial direction becomes gradually flattened, the peak radiation power and the peak ion-temperature almost exponentially increase, while the radiation energy and the peak plasma density change only a little. The main effect of shortening drive current rise-time is to enhance compression of plasma, and the effect of flattening initial load density distribution in the radial direction is to raise the plasma temperature. Both of the approaches elevate the x-ray peak radiation power.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

Dependence of stresses on grain orientations in BCC polycrystalline films on substrates

Zhang Jian-Min, Zhang Yan, Xu Ke-Wei
Chin. Phys., 2005, 14 (9): 1862-1865 doi: 10.1088/1009-1963/14/9/031
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Most thin films have different thermal expansion coefficients from their substrates, thus thermal stresses will be introduced into the films when the temperature is changed during annealing and service. Calculations of these stresses for grains in various crystallographic orientations have been made for seven BCC transition metals Cr, Fe, Mo, Nb, Ta, V and W. Neglecting W, which is isotropic and the stresses are equiaxial and without grain orientation (hkl) dependence, the BCC metals may be grouped into two classes. In the first class (Cr, Mo, Nb and V), the (100)-oriented grains have the largest stresses, while the stresses \sigma _1 and \sigma _2 in other (hkl)-oriented grains decrease linearly with the increase of the angle between (hkl) and (100), and with \sigma _1 < \sigma _2 except in (100)- and (111)-oriented grains. In the second class (Fe and Ta), on the contrary, the (100)-oriented grains have the lowest stresses, and the stresses \sigma _1 and \sigma _2 in other (hkl)-oriented grains increase linearly with the increase of the angle between (hkl) and (100), and with \sigma _1 > \sigma _2 except in (100)- and (111)-oriented grains.

Evaluation of multiaxial stress in textured cubic films by x-ray diffraction

Zhang Jian-Min, Xu Ke-Wei
Chin. Phys., 2005, 14 (9): 1866-1872 doi: 10.1088/1009-1963/14/9/032
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X-ray diffraction is used extensively to determine the residual stress in bulk or thin film materials on the assumptions that the material is composed of fine crystals with random orientation and the stress state is biaxial and homogeneous through the x-ray penetrating region. The stress is calculated from the gradient of \varepsilon \sim \sin ^2\psi linear relation. But the method cannot be used in textured films due to nonlinear relation. In this paper, a novel method is proposed for measuring the multiaxial stresses in cubic films with any \left[ {hkl} \right] fibre texture. As an example, a detailed analysis is given for measuring three-dimensional stresses in FCC films with \left[ {111} \right] fibre texture.

Post-deposition dynamics of multiple cluster aggregation on liquid surfaces

Wu Feng-Min, Xu You-Sheng, Ye Gao-Xiang, Wu Zi-Qin
Chin. Phys., 2005, 14 (9): 1873-1878 doi: 10.1088/1009-1963/14/9/033
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A comprehensive simulation model---deposition, diffusion, rotation and aggregation---is presented to demonstrate the post-deposition phenomena of multiple cluster growth on liquid surfaces, such as post-deposition nucleation, post-deposition growth and post-deposition coalescence. Emphasis is placed on the relaxations of monomer density, dimer density and cluster density as well as combined cluster-plus-monomer density with time after deposition ending. It is shown that post-deposition coalescence largely takes place after deposition due to the large mobility of clusters on liquid surfaces, while the post-deposition nucleation is only possible before the saturation cluster density is reached at the end of the deposition. The deposition flux and the moment of deposition ending play important roles in the post-deposition dynamics.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

Magnetotransport properties of La0.67Ca0.33MnO3/La0.67Sr0.33MnO3 bilayers

Feng Jia-Feng, Zhao Kun, Huang Yan-Hong, Zhao Jian-Gao, Han Xiu-Feng, Zhan Wen-Shan, Wong Hong-Kuen
Chin. Phys., 2005, 14 (9): 1879-1881 doi: 10.1088/1009-1963/14/9/034
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The perovskite bilayers La0.67Ca0.33MnO3 (LCMO) (100nm) / La0.67Sr0.33MnO3(LSMO) (100 nm) and LSMO (100 nm) / LCMO (100 nm) are fabricated by a facing-target sputtering technique. Their transport and magnetic properties are investigated. It is found that the transport properties between them are different obviously due to distinguishable structures, and the different lattice strains in both films result in the difference of metal-to-insulator transition. Only single-step magnetization loop appears in our bilayers from 5K to 320K, and the coercive force of LSMO/LCMO varies irregularly with a minimum \sim 2387A/m which is lower than that of LCMO and LSMO single layer films. The behaviour is explained by some magnetic coupling.

Accelerated oxygen precipitation in fast neutron irradiated Czochralski silicon

Ma Qiao-Yun, Li Yang-Xian, Chen Gui-Feng, Yang Shuai, Liu Li-Li, Niu Ping-Juan, Chen Dong-Feng, Li Hong-Tao
Chin. Phys., 2005, 14 (9): 1882-1885 doi: 10.1088/1009-1963/14/9/035
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Annealing effect of the oxygen precipitation and the induced defects have been investigated on the fast neutron irradiated Czochralski silicon (CZ-Si) by infrared absorption spectrum and the optical microscopy. It is found that the fast neutron irradiation greatly accelerates the oxygen precipitation that leads to a sharp decrease of the interstitial oxygen with the annealing time. At room temperature (RT), the 1107cm-1 infrared absorption band of interstitial oxygen becomes weak and broadens to low energy side. At low temperature, the infrared absorption peaks appear at 1078cm-1, 1096cm-1, and 1182cm-1, related to different shapes of the oxygen precipitates. The bulk microdefects, including stacking faults, dislocations and dislocation loops, were observed by the optical microscopy. New or large stacking faults grow up when the silicon self-interstitial atoms are created and aggregate with oxygen precipitation.

The conduction mechanism of stress induced leakage current through ultra-thin gate oxide under constant voltage stresses

Wang Yan-Gang, Xu Ming-Zhen, Tan Chang-Hua, Zhang J.F., Duan Xiao-Rong
Chin. Phys., 2005, 14 (9): 1886-1891 doi: 10.1088/1009-1963/14/9/036
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The conduction mechanism of stress induced leakage current (SILC) through 2{nm} gate oxide is studied over a gate voltage range between 1.7V and stress voltage under constant voltage stress (CVS). The simulation results show that the SILC is formed by trap-assisted tunnelling (TAT) process which is dominated by oxide traps induced by high field stresses. Their energy levels obtained by this work are approximately 1.9eV from the oxide conduction band, and the traps are believed to be the oxygen-related donor-like defects induced by high field stresses. The dependence of the trap density on stress time and oxide electric field is also investigated.

Structure and magnetic properties of a new single-molecule magnet [Mn11Fe1O12 (CH3COO)16(H2O)4].2CH3COOH.4H2O

Cao Hui-Bo, He Lun-Hua, Wang Fang-Wei
Chin. Phys., 2005, 14 (9): 1892-1895 doi: 10.1088/1009-1963/14/9/037
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A new single-molecule magnet [Mn11Fe1O12 (CH3COO)16(H2O)4]?2CH3COOH?4H2O (Mn11Fe1) has been synthesized.The structure has been studied by the single crystal x-ray diffraction. The difference of Jahn--Teller distortion between Fe3+ and Mn3+ ion reveals that Fe3+ ion substitutes for Mn3+ ion on the Mn(3) sites in the Mn12 skeleton. The temperature dependence of the magnetization gives a blocking temperature TB=1.9K for Mn11Fe1. Based on the magnetization process analysis of the crystal at T=2K, we suggest that Mn11Fe1 has the ground state with a total spin S= 11/2.
Comprehensive Survey for the Frontier Disciplines

Oscillatory electron phonon coupling in Pb/Si(111) deduced by temperature-dependent quantum well states

Zhang Yan-Feng, Jia Jin-Feng, Han Tie-Zhu, Tang Zhe, Shen Quan-Tong, Guo Yang, Xue Qi-Kun
Chin. Phys., 2005, 14 (9): 1910-1914 doi: 10.1088/1009-1963/14/9/041
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Photoemission study of atomically flat Pb films with a thickness from 15 to 24 monolayers (ML) have been performed within a temperature range 75--270K.Well-defined quantum well states (QWSs) are observed, which exhibit interesting temperature-dependent behaviours. The peak position of the QWSs shifts towards higher binding energy with increasing substrate temperature,whereas the peak width broadens linearly due to enhanced electron--phonon coupling strength (\lambda ). An oscillatory \lambda with a period of 2ML is deduced. Preliminary analysis shows that the oscillation can be explained in terms of the interface induced phase variations, and is thus a manifestation of the quantum size effects.
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