Table of contents

15 June 2001, Volume 10 Issue 6 Previous issue    Next issue

GENERAL

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THERMODYNAMICS OF THE SLOWLY ROTATING KERR-NEWMAN BLACK HOLE IN THE GRAND CANONICAL ENSEMBLE Chen Ju-hua (陈菊华), Jing Ji-liang (荆继良), Wang Yong-jiu (王永久) Chinese Physics, 2001, 10 (6):  467-474.  DOI: 10.1088/1009-1963/10/6/301 Abstract ( 1113 )   PDF (246KB) ( 437 )   We investigate the thermodynamics of the slowly rotating Kerr-Newman (K-N) black hole in the grand canonical ensemble with York's formalism. Some thermodynamical properties, such as the thermodynamical action, entropy, thermodynamical energy and heat capacity are studied, and solutions of the slowly rotating K-N black hole with different boundary conditions are analysed. We find stable solutions and instantons under certain boundary conditions.

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THE ELECTRON IN THE GRAVITATIONAL FIELD OF THE KERR BLACK HOLE Wang Yong-jiu (王永久), Tang Zhi-ming (唐智明) Chinese Physics, 2001, 10 (6):  475-479.  DOI: 10.1088/1009-1963/10/6/302 Abstract ( 1165 )   PDF (222KB) ( 457 )   We investigate the electronic energy levels in the field of the micro-Kerr black hole under the approximation condition $a<<GM/c^2$, and obtain some interesting results.

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THE MEAN-SQUARE EXPONENTIAL STABILITY AND INSTABILITY OF STOCHASTIC NONHOLONOMIC SYSTEMS Shang Mei (尚玫), Guo Yong-xin (郭永新) Chinese Physics, 2001, 10 (6):  480-485.  DOI: 10.1088/1009-1963/10/6/303 Abstract ( 1508 )   PDF (253KB) ( 450 )   We present a new methodology for studying the mean-square exponential stability and instability of nonlinear nonholonomic systems under disturbance of Gaussian white-noise by the first approximation. Firstly, we give the linearized equations of nonlinear nonholonomic stochastic systems; then we construct a proper stochastic Lyapunov function to investigate the mean-square exponential stability and instability of the linearized systems, and thus determine the stability and instability in probability of corresponding competing systems. An example is given to illustrate the application procedures.

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QUANTUM FLUCTUATIONS IN MESOSCOPIC RESISTANCE-INDUCTANCE-CAPACITANCE ELECTRIC CIRCUITS AT FINITE TEMPERATURE Liang Xian-ting (梁先庭), Fan Hong-yi (范洪义) Chinese Physics, 2001, 10 (6):  486-489.  DOI: 10.1088/1009-1963/10/6/304 Abstract ( 1292 )   PDF (203KB) ( 760 )   By using the charge and current in a quantization resistance-inductance-capacitance (RLC) electric circuit, we construct a pair of canonical variables. Using this pair of variables and the thermal field dynamics, we obtain the fluctuations of charge and current in the RLC electric circuit at finite temperatures. It is shown that the fluctuations increase with increasing temperature and decrease with prolonging of time.

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QUANTUM FLUCTUATIONS IN A MESOSCOPIC DAMPED LC PARALLEL CIRCUIT IN DISPLACED SQUEEZED FOCK STATE Gu Yong-jian (顾永建) Chinese Physics, 2001, 10 (6):  490-493.  DOI: 10.1088/1009-1963/10/6/305 Abstract ( 1288 )   PDF (94KB) ( 570 )   We study the quantum effects of a damped LC parallel circuit considering its different performance from an RLC series circuit in classical physics. The damped LC parallel circuit with a source is quantized and the quantum fluctuations of magnetic flux and electric charge in the circuit in displaced squeezed Fock state are investigated. It is shown that, as in the RLC series circuit, the fluctuations only depend on the squeezing parameter and the parameters of the circuit components in the damped LC parallel circuit, but the effects of the circuit components on the fluctuations are different in the two circuits.

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ADAPTIVE CONTROL AND IDENTIFICATION OF CHAOTIC SYSTEMS Li Zhi (李智), Han Chong-zhao (韩崇昭) Chinese Physics, 2001, 10 (6):  494-496.  DOI: 10.1088/1009-1963/10/6/306 Abstract ( 1082 )   PDF (99KB) ( 511 )   A novel adaptive control and identification on-line method is proposed for a class of chaotic system with uncertain parameters. We prove that, using the presented method, a controller and identifier is developed which can remove chaos in nonlinear systems and make the system asymptotically stabilizing to an arbitrarily desired smooth orbit. And at the same time, estimates to uncertain parameters converge to their true values. The advantage of our method over the existing result is that the controller and identifier is directly constructed by analytic formula without knowing unknown bounds about uncertain parameters in advance. A computer simulation example is given to validate the proposed approach.

THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

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CALCULATION OF KAON ELECTROMAGNETIC FORM FACTOR Wang Zhi-gang (王志刚), Wan Shao-long (完绍龙), Wang Ke-lin (汪克林) Chinese Physics, 2001, 10 (6):  497-500.  DOI: 10.1088/1009-1963/10/6/307 Abstract ( 878 )   PDF (112KB) ( 443 )   The kaon meson electromagnetic form factor is calculated in the framework of coupled Schwinger-Dyson and Bethe-Salpeter formulation in simplified impulse approximation (dressed vertex) with modified flat-bottom potential, which is a combination of the flat-bottom potential taking into consideration the infrared and ultraviolet asymptotic behaviours of the effective quark-gluon coupling. All the numerical results give a good fit to experimental values.

ATOMIC AND MOLECULAR PHYSICS

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STUDY OF ANALYTIC POTENTIAL ENERGY FUNCTION AND STABILITY FOR PuOn+ WITH DENSITY FUNCTIONAL THEORY Li Quan (李权), Liu Xiao-ya (刘晓亚), Wang Rong (汪蓉), Zhu Zheng-he (朱正和), Fu Yi-bei (傅依备), Wang Xiao-lin (汪小琳) Chinese Physics, 2001, 10 (6):  501-504.  DOI: 10.1088/1009-1963/10/6/308 Abstract ( 1196 )   PDF (126KB) ( 552 )   The theoretical study of PuOn+(n=1,2,3) using a density functional method shows that PuO+ (X6$\Sigma$-) and PuO2+(X5$\Sigma$-, 7$\Sigma$-, 9$\Sigma$-) ions are stable, and the PuO3+ (4$\Sigma$+, 6$\Sigma$+) ion is unstable. The analytic potential energy functions of X6$\Sigma$- for PuO+ and X5$\Sigma$-, 7$\Sigma$-, 9$\Sigma$- for PuO2+ have been derived, and their force constants and spectroscopic data have been calculated.

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CALCULATION OF THE FINE STRUCTURE OF OXYGEN-LIKE IONS USING THE POLARIZATION POTENTIAL FUNCTION Sheng Yong (盛勇), Wang Rong (汪蓉), Jiang Gang (蒋刚), Zhu Zheng-he (朱正和) Chinese Physics, 2001, 10 (6):  505-511.  DOI: 10.1088/1009-1963/10/6/309 Abstract ( 1144 )   PDF (157KB) ( 474 )   We have calculated the forbidden transition energies and magnetic dipole transition probabilities of 2s22p4(3P1－3P2) and 2s22p4 (3P0－3P1) of oxygen-like isoelectronic sequences (Z=10－32) by a method of polarization potential correction. The transition energies show good agreement with experiment and are much better than the calculations in the literature. These results also illustrate that it is feasible to use the dipole expansion of the polarization potential to deal with some dynamic and non-dynamic effects in the central field approach. The relation of polarizability and cut-off radius with atomic number is discussed. We also give the fitted formula between the polarizability $\alpha_1$ and atomic number Z as $\alpha_1$ = 0.73429-9.56644×10-4Z+7.43016×10-5Z2-2.53298×10-6Z3+2.08306×10-8Z4.

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MEASUREMENT OF HYPERFINE COUPLING CONSTANTS OF THE EXCITED STATES 4f7(8S07/2)6p3/2(7/2, 3/2) IN 151,153Eu+ Ma Hong-liang (马洪良), Yang Fu-jia (杨福家) Chinese Physics, 2001, 10 (6):  512-515.  DOI: 10.1088/1009-1963/10/6/310 Abstract ( 1412 )   PDF (136KB) ( 506 )   Hyperfine structure spectra of singly ionized europium have been measured by collinear fast-ion-beam laser spectroscopy. All the spectral lines were resolved and the magnetic dipole and electric quadrupole coupling constants of the metastable and excited levels were determined.

CLASSICAL AREAS OF PHENOMENOLOGY

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AN ANALYTIC MODEL FOR TRANSIENT COLLISIONAL X-RAY LASERS Li Ying-jun (李英骏), Zhang Jie (张杰), Teng Ai-ping (滕爱萍) Chinese Physics, 2001, 10 (6):  516-522.  DOI: 10.1088/1009-1963/10/6/311 Abstract ( 1096 )   PDF (207KB) ( 499 )   A set of similarity equations is derived to describe the hydrodynamics of transient X-ray lasers from slab plasmas generated by combined irradiation of nanosecond and picosecond laser pulses. By separating nanosecond and picosecond laser heating processes into different periods, analytical solutions are obtained for the similarity equations. The calculated results are in agreement with numerical simulations and experimental data.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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PARAMETRIC SIMULTONS IN ONE-DIMENSIONAL NONLINEAR LATTICES Huang Guo-xiang (黄国翔) Chinese Physics, 2001, 10 (6):  523-530.  DOI: 10.1088/1009-1963/10/6/312 Abstract ( 894 )   PDF (261KB) ( 471 )   Parametric simultaneous solitary wave (simulton) excitations are shown to be possible in nonlinear lattices. Taking a one-dimensional diatomic lattice with a cubic potential as an example, we consider the nonlinear coupling between the upper cut-off mode of acoustic branch (as a fundamental wave) and the upper cut-off mode of optical branch (as a second harmonic wave). Based on a quasi-discreteness approach the Karamzin－Sukhorukov equations for two slowly varying amplitudes of the fundamental and the second harmonic waves in the lattice are derived when the condition of second harmonic generation is satisfied. The lattice simulton solutions are given explicitly and the results show that these lattice simultons can be nonpropagating when the wave vectors of the fundamental wave and the second harmonic waves are exactly at $\pi/a$ (where a is the lattice constant) and zero, respectively.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

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ELECTRONIC PROPERTIES OF CARBON NANOTUBES WITH A PENTAGON-HEPTAGON PAIR DEFECT Hu Hui-fang (胡慧芳), Li Yi-bing (李义兵), Zhou Wei-ya (周维亚), Tang Dong-sheng (唐东升) Chinese Physics, 2001, 10 (6):  531-536.  DOI: 10.1088/1009-1963/10/6/313 Abstract ( 1099 )   PDF (160KB) ( 552 )   The features of energetics and electronic properties of carbon nanotubes, containing a pentagon-heptagon pair (5/7) topological defect in the hexagonal network of the zigzag configuration, are investigated using the extended Su-Schriffer-Heeger model based on the tight binding approximation in real space. Our calculations show that this pentagon-heptagon pair defect in the nanotube structures is not only responsible for a change in nanotube diameter, but also governs the electronic behaviour around Fermi level. Furthermore, we have calculated the densities of states of the (9,0)-(8,0) and (8,0)-(7,0) systems. For the (9,0)-(8,0) system, a narrow gap exists in the vicinity of the Fermi energy. In contrast, for the (8,0)-(7,0) system, a little peak of the density of states occurs at the Fermi energy. These can be attributed to the addition of a pair of pentagon-heptagon defects in the interface between two isolated carbon nanotubes.

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AN EFFECTIVE TWO-LEVEL CHANNEL FOR AN IMPURITY IN A SUPERLATTICE Zhang Ai-zhen (张爱珍), Zhang Ping (张平), Duan Su-qing (段素青), Zhao Xian-geng (赵宪庚), Liang Jiu-qing (梁九卿) Chinese Physics, 2001, 10 (6):  537-540.  DOI: 10.1088/1009-1963/10/6/314 Abstract ( 1059 )   PDF (207KB) ( 612 )   The eigenstates and eigenspectrum of a charged particle in a one-dimensional semiconductor superlattice with an impurity under the action of a dc electric field are investigated employing the single-band tight-binding model. We find that the system undergoes a series of avoided crossings, at which resonant oscillations between the impurity and its nearest neighbour occur if appropriate conditions are met, suggesting an effective two-level approximation. This phenomenon shows that introducing an impurity in a perfect lattice provides a promising structure for the observation of terahertz radiation.

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GINZBURG-LANDAU THEORY AND VORTEX LATTICE OF HIGH-TEMPERATURE SUPERCONDUCTORS Zhou Shi-ping (周世平) Chinese Physics, 2001, 10 (6):  541-549.  DOI: 10.1088/1009-1963/10/6/315 Abstract ( 976 )   PDF (344KB) ( 499 )   The thermodynamics of the vortex lattice of high-temperature superconductors has been studied by solving the generalized Ginzburg-Landau equations derived microscopically. Our numerical simulation indicates that the structure of the vortex lattice is oblique at the temperature far away from the transition temperature Tc, where the mixed s-d$_{x^2-y^2}$ state is expected to have the lowest energy. Whereas, very close to Tc, the d$_{x^2-y^2}$ wave is slightly lower energetically, and a triangular vortex lattice recovers. The coexistence and the coupling between the s and d waves would account for the unusual dynamic behaviours such as the upward curvature of the upper critical field curve HC2(T), as observed in dc magnetization measurements on single-crystal YBa2Cu3O7 samples.

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THE LAX PAIR FOR C2-TYPE RUIJSENAARS-SCHNEIDER MODEL Chen Kai (陈凯), Hou Bo-yu (侯伯宇), Yang Wen-li (杨文力) Chinese Physics, 2001, 10 (6):  550-554.  DOI: 10.1088/1009-1963/10/6/316 Abstract ( 1185 )   PDF (224KB) ( 428 )   We study the C2 Ruijsenaars-Schneider model with interaction potential of trigonometric type. The Lax pairs for the model with and without spectral parameters are constructed. Also given are the involutive Hamiltonians for the system. Taking a non-relativistic limit, we obtain the Lax pair of C2 Calogero-Moser model.

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INTER-GRAIN EXCHANGE INTERACTION FOR SINGLE-PHASE NANOCRYSTALLINE Nd-Fe-B MAGNETS Wang Xue-feng (王学凤), Jin Han-min (金汉民), Zhao Su-fen (赵素芬), Yan Yu (闫羽) Chinese Physics, 2001, 10 (6):  555-557.  DOI: 10.1088/1009-1963/10/6/317 Abstract ( 1020 )   PDF (136KB) ( 505 )   The demagnetization curve as a function of intensity of the inter-grain exchange interaction was calculated for single-phase nanocrystalline Nd-Fe-B magnets by use of the finite-element technique of micromagnetics. Also, the strength of the exchange interaction was estimated as a function of the Nd content x for the nanocrystalline NdxFe94-xB6 magnets by comparing the above result with the experimental relation between iHc and x for the magnets. We found that the inter-grain exchange interaction decreases with the increase of x, are ≈70% and ≈60% of the inter-grain exchange interaction for x=15.5($\mu$0iHc≈2.0T) and x=19($\mu$0iHc≈2.3T), respectively.

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DIRECT MEASUREMENT OF TRANSVERSE RELAXATION TIME OF INTERMOLECULAR MULTIPLE QUANTUM COHERENCES IN NMR Zheng Shao-kuan (郑绍宽), Chen Zhong (陈忠), Chen Zhi-wei (陈志伟), Zhong Jian-hui (钟健晖) Chinese Physics, 2001, 10 (6):  558-563.  DOI: 10.1088/1009-1963/10/6/318 Abstract ( 1050 )   PDF (147KB) ( 479 )   A one-dimensional NMR method is presented for measuring the transverse relaxation time, T2,n, of intermolecular multiple quantum coherences (IMQCs) of coherence order n in highly polarized spin systems. The pulse sequence proposed in this paper effectively suppresses the effects of radiation damping, molecular diffusion, inhomogeneity of magnetic field, and variations of dipolar correlation distance, all of which may affect quantitation of T2,n. This pulse sequence can be used to measure not only IMQC transverse relaxation time T2,n (n>1) quickly and directly, but also the conventional transverse relaxation time. Experimental results demonstrate that the quantitative relationship between T2,n (n≥1) and T2 is T2,n ≈T2/n. These results will be helpful for understanding the fundamental properties and mechanisms of IMQCs.

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BLUE COOPERATIVE UP-CONVERSION LUMINESCENCE OF Yb3+ IONS IN OXYFLUORIDE GLASS EXCITED BY 960 nm LASER Chen Xiao-bo (陈晓波), Song Zeng-fu (宋增福), N. Sawanobori Chinese Physics, 2001, 10 (6):  564-567.  DOI: 10.1088/1009-1963/10/6/319 Abstract ( 981 )   PDF (120KB) ( 475 )   Investigates the up-conversion luminescence of Yb-doped oxyfluoride glass excited by a 960nm-diode laser. A new up-conversion cooperative radiation luminescence is found, which is rather strong and positioned at 476.1 nm. It comes from the coupled states of two-Yb3+-ions cluster. It is significant because it is an effective and convenient method of producing bluelight.

GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS

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GAMMA-RAY AND X-RAY EMISSION FROM GAMMA-RAY-LOUD BLAZARS Zhang Xiong (张雄), Zhao Gang (赵刚), Xie Guang-zhong (谢光中), Zheng Guang-sheng (郑广生), Zhang Li (张力) Chinese Physics, 2001, 10 (6):  568-574.  DOI: 10.1088/1009-1963/10/6/320 Abstract ( 953 )   PDF (347KB) ( 448 )   We present a strong correlation of the gamma-ray (above 100 MeV) mean spectral indices $\alpha_\gamma$ and X-ray (1 keV) mean spectral indices $\alpha$X for 34 gamma-ray-loud blazars (16 BL Lac objects and 18 flat spectrum radio quasars). A strong correlation is also found between the gamma-ray flux densities $F_\gamma$ and X-ray flux densities FX in the low state for 47 blazars (17 BL Lac and 30 flat spectrum radio quasars). Possible correlation on the gamma-ray emission mechanism is discussed. We suggest that the main gamma-ray radiation mechanism is probably the synchrotron process. The gamma-ray emission may be somewhat different from that of BL Lac objects and flat spectrum radio quasars.