Current Issue

Volume 20 Issue 1
Online Date:
Previous Issue    Next Issue
Original Articles
Critical Pressure of the Structure I Empty Gas Hydrate
Chin. Phys. Lett. 2003, 20 (1): 1-4 .  
Abstract   PDF(pc) (407KB) ( 425 )
A 368 water molecule structure I empty gas hydrate with possible minimum energy are calculated under high pressures by using TIP4P potential molecular dynamical simulations. Thermodynamical properties are analysed. Radial distribution function and phonon density of states shows that there is a phase transition to high-density ice at low temperature.

Absurd Results from the Expression of Expectation Values of “Double-Wave Theory”
ZHU Zhen-He
Chin. Phys. Lett. 2003, 20 (1): 5-7 .  
Abstract   PDF(pc) (184KB) ( 407 )
Two of the four fundamental hypotheses of the double-wave theory (DWT) are criticized. It is expounded that the hypothesis of two wave functions is unreasonable and the hypothesized expression of measured values or expectation values of mechanical quantities is wrong and does not express the measured values or expectation values at all. This expression can lead to some absurd results.
One-Dimensional Potentials in q Space
S. A. Alavi
Chin. Phys. Lett. 2003, 20 (1): 8-11 .  
Abstract   PDF(pc) (214KB) ( 632 )
We study one-dimensional potentials in q space and the new features that arise. In particular, we show that the probability of tunneling of a particle through a barrier or potential step is less than that of the same particle with the same energy in ordinary space which is somehow unexpected. We also show that the tunneling time for a particle in q space is less than that of the same particle in ordinary space.

Mesoscopic Persistent Currents, Aharonov-Bohm Magnetic Flux and Time Reversal Symmetry
LI Hua-Zhong
Chin. Phys. Lett. 2003, 20 (1): 12-13 .  
Abstract   PDF(pc) (148KB) ( 360 )
We discuss the effect of Aharonov-Bohm magnetic flux on the time reversal symmetric properties of mesoscopic metallic ring systems. It is usually believed that AB flux causes time reversal symmetry breaking. We analysis the case of mesoscopic persistent currents and find out that AB flux does not break time resversal symmetry. Our arguments are supported by general theory of mesoscopic persistent currents.

Teleported State and its Fidelity in Quantum Teleportation of Continuous Variables
LI Fu-Li, LI Hong-Rong, ZHANG Jun-Xiang, ZHU Shi-Yao
Chin. Phys. Lett. 2003, 20 (1): 14-17 .  
Abstract   PDF(pc) (228KB) ( 559 )
When given an unknown quantum state which may be either a pure or mixed state in the coherent state representation, we show that explicit expressions for the teleported state and its fidelity in the teleportation process (S.L. Braunstein and H. J. Kimble, Phys. Rev. Lett. 80(1998)869) can be obtained without explict expansions for the two-mode squeezed vacuum state and the Bell basis in a specified representation.
Quantum Statistical Entropy of Non-extreme and Nearly Extreme Black Holes in Higher-Dimensional Space-Time
XU Dian-Yan
Chin. Phys. Lett. 2003, 20 (1): 18-21 .  
Abstract   PDF(pc) (218KB) ( 332 )
The free energy and entropy of Reissner-Nordstrom black holes in higher-dimensional space-time are calculated by the quantum statistic method with a brick wall model. The space-time of the black holes is divided into three regions: region 1, (r > ro) region 2, (ro > r > ri); and region 3, (ri > r > 0), where ro is the radius of the outer event horizon, and ri is the radius of the inner event horizon. The detailed calculation shows that the entropy contributed by region 2 is zero, the entropy contributed by region 1 is positive and proportional to the outer event horizon area, the entropy contributed by region 3 is negative and proportional to the inner event horizon area. The total entropy contributed by all the three regions is positive and proportional to the area difference between the outer and inner event horizons. As ri approaches ro in the nearly extreme case, the total quantum statistical entropy approaches zero.

Breakdown of an Inhomogeneous Scale-Free Network Under Intentional Attack
Chin. Phys. Lett. 2003, 20 (1): 22-24 .  
Abstract   PDF(pc) (311KB) ( 780 )
Using a recently introduced network model with node and connection diversity, we study the breakdown of different scale-free networks under intentional attacks. Our simulation results show that inhomogeneous networks are more sensitive to intentional attack than the homogeneous ones and that the centralization of the networks is an important variable, reflecting the characteristics of the network under intentional attack. Using a recently introduced method we can theoretically develop the critical point of the inhomogeneous networks.
Stochastic Resonance in Linear Regime of a Single-Mode Laser
ZHANG Liang-Ying, CAO Li, WU Da-Jin, WANG Jun
Chin. Phys. Lett. 2003, 20 (1): 25-27 .  
Abstract   PDF(pc) (327KB) ( 569 )
We present an analytic investigation of the signal-to-noise ratio by studying the linear model of a single-mode laser driven by colored pump noise (τ1) and colored quantum noise (τ2) with colored cross-correlation (τ3), and obtain an exact analytic expression of the signal-to-noise ratio. We detect that the stochastic resonance occurs when the noise correlation coefficient λ < 0. Furthermore, we analyse the effect of τ1, τ2, and τ3 on the signal-to-noise ratio, and derive the condition under which the stochastic resonance occurs.

Experimental Analysis of Stochastic Resonance in a Duffing System
WANG Fu-Zhong, CHEN Wei-Shi, QIN Guang-Rong, GUO De-Yong, LIU Jun-Ling
Chin. Phys. Lett. 2003, 20 (1): 28-30 .  
Abstract   PDF(pc) (456KB) ( 449 )
An experimental circuit is used to study the stochastic resonance (SR) phenomena in a Duffing system. The characteristics of SR are investigated from various aspects by varying all the possible parameters. The deviations between the experimental results and the adiabatic theory are presented.

Information Measure for Size Distribution of Avalanches in the Bak-Sneppen Evolution Model
LI Wei, CAI Xu
Chin. Phys. Lett. 2003, 20 (1): 31-34 .  
Abstract   PDF(pc) (262KB) ( 406 )
Information of avalanche size distribution is measured by calculating information entropy (IE) in the Bak-Sneppen evolution model. It is found that the IE increases as the model evolves. Specifically, we establish the relation between the IE and the self-organized threshold fc. The variation of the IE near the critical point yields an exponent entropy index E = (τ - 1)/σ, where τ and σ represent the critical exponents for avalanche size distribution and avalanche size cutoff, respectively. A new quantity Dτ(g) (g = 1-(fc-G)(τ - 1)/σ, where G is the gap of the current state), defined as 1-Iτ(g)/Iτ(1), with Iτ(g) and Iτ(1) being the IE for the current state and the critical one respectively, is suggested that it represent the distance between the state with gap G and the critical one.

Calculation of the Specific Heats for the II-III and II-IV Phase Transitions in NH4I
H. Yurtseven, H. Kaya
Chin. Phys. Lett. 2003, 20 (1): 35-38 .  
Abstract   PDF(pc) (334KB) ( 400 )
This study gives our calculation for the specific heats CVI due to an Ising model using the observed Cp data for the II-III and II-IV phase transitions in NH4I. By fitting to the Cp data we determine the values of the critical exponent for the pressure of 0.14 GPa (II-III phase transition) and for the pressures of 0.75, 1.35 and 1.97 GPa (II-IV phase transition) in NH4I. Our exponent values are close to the predicted values of the specific heat in a three-dimensional Ising model. Our calculated CVI are in good agreement with the experimental Cp for NH4I in most cases.

Solitons in a Heisenberg Spin Chain with an Easy Axis Under an Oscillating Magnetic Field
LI Zai-Dong, LI Lu, LIANG Jiu-Qing,
Chin. Phys. Lett. 2003, 20 (1): 39-41 .  
Abstract   PDF(pc) (187KB) ( 655 )
The Lax pair is given for the equations of motion of a continuum-Heisenberg-spin chain of an easy axis in an oscillating magnetic field. Using an inverse scattering transformation we derive soliton solutions for the case of the easy axis.
Nucleon-Nucleon Phase Shifts in the Extended Quark-Delocalization Colour-Screening Model
LU Xi-Feng, PING Jia-Lun, WANG Fan
Chin. Phys. Lett. 2003, 20 (1): 42-45 .  
Abstract   PDF(pc) (367KB) ( 437 )
An alternative method is applied to the study of nucleon-nucleon scattering phase shifts within the framework of the extended quark delocalization colour-screening model, in which the one-pion-exchange with short-range cutoff is included.
Isospin Effect of the Pairing Correlation in Al Isotopes
ZHANG Hu-Yong, SHEN Wen-Qing, REN Zhong-Zhou, MA Yu-Gang, CAI Xiang-Zhou, ZHONG Chen, WEI Yi-Bin, CHEN Jin-Gen, ZHOU Xing-Fei, MA Guo-Liang, WANG Kun
Chin. Phys. Lett. 2003, 20 (1): 46-48 .  
Abstract   PDF(pc) (307KB) ( 496 )
The binding energies of Al isotopes are investigated by using the Skyrme-Hartree-Fock approach with the SKIII force parameter. Special emphasis is placed on the influence of the isospin effect of the pairing correlation on the neutron separation energy. Calculations show that the Skyrme-Hartree-Fock approach provides a good description of the binding energy of Al isotopes with different forms of pairing correlation. Meanwhile, it is found that the isospin effect of the pairing correlation plays a great role to the separation energy when the Al isotopes approach to the proton drip line.
Calculation of Cross Section of Radiative Halo-Neutron Capture by 12C at Stellar Energy with the Asymptotic Normalization Coefficient Method
WU Kai-Su, CHEN Yong-Shou, LIU Zu-Hua, LIN Cheng-Jian, ZHANG Huan-Qiao
Chin. Phys. Lett. 2003, 20 (1): 49-52 .  
Abstract   PDF(pc) (287KB) ( 427 )
The cross section of the direct neutron capture reaction 12C(n,γ)13C(1/2+) is calculated with the asymptotic normalization coefficient method. The result is in good agreement with a recent experiment at low energy. An enormous enhancement of cross section is found for this direct neutron capture in which a p-wave neutron is captured into an 2s1/2 orbit with neutron halo. The possible effect of the neutron halo structure presented in this reaction on the s-process in astrophysics is discussed in general.

Halo Structure of Nucleus 23Al
ZHAO Yao-Lin, MA Zhong-Yu, , CHEN Bao-Qiu, SHEN Wen-Qing,
Chin. Phys. Lett. 2003, 20 (1): 53-55 .  
Abstract   PDF(pc) (286KB) ( 499 )
The recently measured reaction cross section of 23Al is analysed in the Glauber model with an optical limit or few-body approach. It is found that the conventional fixed core-plus-nucleon model for halo nuclei is unable to explain the observed abnormally large reaction cross section of 23Al by any selection of the halo nucleon configurations. The reaction cross section of 23Al can be described when the core size is enlarged, although the Coulomb barrier largely hinders the formation of a halo structure for proton-rich nuclei. This is consistent with the case in s-d shell neutron-rich nuclei, where an enlarged core was proposed to explain both the reaction cross section and longitudinal momentum distribution data.
Relativistic Multichannel Theory: Theoretical Study of C+ Autoionization States
XIA Dan, ZHANG Shi-Zhong, PENG Yong-Lun, LI Jia-Ming,
Chin. Phys. Lett. 2003, 20 (1): 56-59 .  
Abstract   PDF(pc) (391KB) ( 383 )
Based on relativistic multichannel theory, the autoionization states of C+ are studied. We calculate all the autoionization states in the energy region of 193900 ~ 231700cm-1, and the results are in good agreement with experimental data. The energy structure we obtain will be important in the dielectronic recombination processes, which play a key role to determine the abundance of carbon in a nebula.

A Calculation of Direct Radiative Recombination Cross Sections and Rate Coefficients
XIA Hai-Ning, CHEN Chong-Yang, SHI Xi-Heng, QI Jing-Bo, WANG Yan-Sen
Chin. Phys. Lett. 2003, 20 (1): 60-63 .  
Abstract   PDF(pc) (470KB) ( 431 )
We calculate direct radiative recombination cross sections and rate coefficients for Be-like O4+, Si10+ and Na-like Fe15+ using nonrelativistic dipole approximation. In order to incorporate the screening effect due to the inner shell electrons in the calculation, we use the distorted wave method instead of pure coulomb approximation with effective charge. The calculated cross sections and rate coefficients are in agreement with other theoretical calculations and the experimental data.

Optical Beams in Media with Spatial Dispersion
Chin. Phys. Lett. 2003, 20 (1): 64-67 .  
Abstract   PDF(pc) (355KB) ( 738 )
We theoretically predict a novel phenomenon of the diffraction-free propagation of the paraxial optical beam in the isotropic or cubic linear medium with spatial dispersion. Under the weak spatial dispersion condition, the paraxial wave equation is derived, in which there is the diffraction term with the coefficient G that depends on the compensation between the classic diffraction and spatial dispersion. Near the exciton dipole absorption line, we can have Γ = 0, then the beam propagates diffraction-freely, and its shape keeps unchangeable. Discussed are also the physical mechanism and the possible experimental candidates of crystals for the phenomenon.

Properties of Movement and Boiling of Speckles Produced by Moving Objects Illuminated with Partially Coherent Light
TENG Shu-Yun, CHENG Chuan-Fu, LIU Man, LIU Li-Ren, XU Zhi-Zhan
Chin. Phys. Lett. 2003, 20 (1): 68-71 .  
Abstract   PDF(pc) (519KB) ( 331 )
Properties of movement and the boiling of dynamic partially coherent speckles are investigated. Theoretical analysis of the correlation functions shows that in front of and behind the Fraunhofer plane, the directions of the movement of the dynamics partially coherent speckles are the same and opposite to that of the object, respectively. The boiling occurs according to a parabolic factor with respect to time separation τ. These properties are observed experimentally by using an elaborately chosen extended source to meet the requirement of intensity and coherence. The boiling of the speckles is measured with the photon counting system, which is refitted for the automatic data acquisition, and the experimental results are conformed by the theory.

Simultaneous Measurement of Transverse Load and Temperature Using a Single Long-Period Fiber Grating Element
RAO Yun-Jiang, WANG Yi-Ping, ZHU Tao, RAN Zeng-Ling
Chin. Phys. Lett. 2003, 20 (1): 72-75 .  
Abstract   PDF(pc) (511KB) ( 448 )
A single long-period fiber grating (LPFG) element written by focused high-frequency CO2 laser pulses is demonstrated for simultaneous measurement of transverse load and temperature. Temperature and transverse load can be directly measured by detecting the resonant wavelength shift and the resonant peak amplitude change of the LPFG, respectively, as there are two special circular orientations along the fiber axis where the resonant peak amplitude change of the LPFG has a linear relationship with the load applied and is insensitive to the resonant wavelength shift. Such a sensor could solve the cross-sensitivity problem between transverse load and temperature due to the unique feature of this type of LPFG, i.e. the wavelength-load-sensitivity of the LPFG strongly depends on loading orientations due to the non-uniform distribution of the refractive index on the cross-section of the LPFG caused by the thermal shock effect and other effects of the high-frequency CO2 laser pulses exposure method used.

Modeling of Laser-Generated Guided Waves in Bonded Plates with a Weak Interface by the Two-Layer Normal Mode Expansion Method
DU Jun, CHENG Jian-Chun
Chin. Phys. Lett. 2003, 20 (1): 76-79 .  
Abstract   PDF(pc) (434KB) ( 399 )
The two-layer normal mode expansion method is employed to analyse the laser-generated elastic guided waves in bonded plates accounting for the adhesive bond layer in terms of a weak interface with the spring model. The sensitivity of dispersion and transient characteristics of the guided wave to the stiffness coefficients characterizing the cohesive quality is analysed in details. This method provides a new promising way for the characterization of the cohesive quality in bonded plates.

Finite-Amplitude Vibration of a Bubble
QIAN Zu-Wen, XIAO Ling
Chin. Phys. Lett. 2003, 20 (1): 80-82 .  
Abstract   PDF(pc) (422KB) ( 439 )
The Rayleigh-Plesset equation for bubble vibration is modified. The numerical solution of new equation is obtained by means of the symbolic computation programme. The acceleration of the liquid on the surface of the bubble, or pressure in the bubble, displays much intense δ-impulse with a very short duration from ns to ps. Suggestions for developing the measurements of sonoluminescence and cavitation fusion (if any) are presented.

Bifurcation Behaviour in the Reverse-Flow Boundary Layer with Special Injection or Suction
ZHENG Lian-Cun, ZHANG Xin-Xin, HE Ji-Cheng
Chin. Phys. Lett. 2003, 20 (1): 83-86 .  
Abstract   PDF(pc) (494KB) ( 397 )
Bifurcation solutions are numerically presented for reverse flow boundary layer equations with special suction/injection by utilizing similarity transformation and shooting technique. The results indicate that both superior solution and inferior solution are noticeable. The skin friction and shear stress for the superior solution decrease with the increases of the ratio of surface velocity to free stream velocity and suction/injection. The behaviour is opposite to that for the inferior solution. Both the skin frictions for the superior and inferior solutions decrease with the increase of the power law parameter. The inferior solution approaches the superior solution with the increase of the velocity ratio and suction/injection. When power law is unit and suction/injection is zero, the superior solution approaches the classical Blasius solution as the velocity ratio approaches zero.

Self-Organized Criticality Processes in HL-1M Tokamak Plasma
HUANG Yuan, QIU Xiao-Ming, DING Xuan-Tong, WANG En-Yao
Chin. Phys. Lett. 2003, 20 (1): 87-89 .  
Abstract   PDF(pc) (325KB) ( 324 )
We study the dynamics of laminar time between successive bursts in anomalous particle flux measured at the HL-1M tokamak plasma edge. The results reveal that the flux fluctuations are self-similar in a narrow range of time scales and that their probability distribution function is not Gaussian. These properties are not consistent with those predicted by self-organized criticality (SOC) models as well as the running sand-pile SOC model developed by Hwa and Kardar.

Radiation Heat Waves in Gold Plasma
YANG Jia-Min, XU Yan, DING Yao-Nan, LAI Dong-Xian, DING Yong-Kun, JIANG Shao-En, ZHENG Zhi-Jian, MIAO Wen-Yong
Chin. Phys. Lett. 2003, 20 (1): 90-92 .  
Abstract   PDF(pc) (363KB) ( 669 )
Eight beams 0.35μm laser with pulse duration of about 1.0 ns and energy of 260 J per beam was injected into a cylindrical cavity to generate intense x-ray radiation on the “Shengguang II”high power laser facility. Gold foils with a thickness in the range of 0.09-0.52μm were attached on the diagnostic hole of the cavity and ablated by the intense x-ray radiation. The propagating radiation heat wave in the high-Z gold plasma was observed clearly. For comparison, we also simulated the experimental results.

Particle Confinement Improvement with Current Ramp in the HL-1M Tokamak
YAN Long-Wen, WANG En-Yao, QIAN Jun, CHEN Liao-Yuan, LIU Yong
Chin. Phys. Lett. 2003, 20 (1): 93-95 .  
Abstract   PDF(pc) (484KB) ( 393 )
Particle confinement with current ramp is investigated in the HL-1M tokamak. The ratio of particle confinement time to energy confinement time is used to determine confinement improvement. It increases a factor of 3 after the current rises twofold. An optimization density range to improve particle confinement is (1.5-3.5) x 1019m-3. Particle confinement improvement during current ramp-up is beneficial to the startup of fusion reactors.

A New High Power Microwave Source Operated at Low Magnetic Field
YANG Jian-Hua, ZHANG Ya-Zhou, ZHANG Jian-De, SHU-Ting, LI Chuan-Lu
Chin. Phys. Lett. 2003, 20 (1): 96-98 .  
Abstract   PDF(pc) (457KB) ( 474 )
A new type of high power microwave source operated at low magnetic field is proposed and studied by the particle-in-cell (PIC) method. An oversized uniform backward-wave-oscillator-like structure is connected to a tapered slow-wave structure by a resonant cavity. In this device, the electron beam current is effectively used to yield microwaves with high efficiency, and the mode is locked in a wide range of diode voltage to reduce the requirement to the voltage wave form. The PIC simulation results show that a peak microwave power of 2.1 GW (averaged 1.1 GW) with a pure TM01 mode at 10.7 GHz is radiated with 4.1 GW input beam power, the frequency remains approximately the same when the diode voltage changed from 300 kV to 700 kV.

Structural Evolution of Nanostructured γ-Ni-28Fe Alloy Investigated by Using the Internal Friction Technique
LIU Yin, QIN Xiao-Ying, WANG Li, ZHANG Ming-Xu
Chin. Phys. Lett. 2003, 20 (1): 99-101 .  
Abstract   PDF(pc) (376KB) ( 513 )
The structural evolution of nanostructured γ-Ni-28Fe alloy (n-Ni-Fe) (grain size d ~ 30 nm), synthesized by the mechno-chemical method, was investigated by using the internal friction technique combined with differential scanning calorimetry (DSC) in the temperature range from 300 K to 670 K. An internal friction peak with typical characteristics of the first-order phase transition was observed in the vicinity of 620 K, which corresponds to a broad exothermic process revealed by using DSC. These results can be explained as the structural changes from the disordering to the ordering transition in the n-Ni-Fe sample.
P-Type Doping of GaN by Mg+ Implantation
YAO Shu-De, ZHOU Sheng-Qiang, YANG Zi-Jian, LU Yi-Hong, SUN Chang-Chun, SUN Chang, ZHANG Guo-Yi, VANTOMME Andre, PIPELEERS Bert, ZHAO Qiang
Chin. Phys. Lett. 2003, 20 (1): 102-104 .  
Abstract   PDF(pc) (395KB) ( 884 )
Mg+ and Mg+ + P+ were introduced into GaN by ion implantation. The structure and crystalline quality of the GaN samples were analysed by Rutherford backscattering and channeling spectrometry before (Xmin = 1.6%) and after implantation (Xmin = 4.1%). X-ray diffraction reveals the existence of implantation-induced damage in the case of post-implantation followed by rapid thermal annealing. The resistivity, average factor, carrier concentration and carrier mobility were measured by the Hall effect. The transformation from n-type to p-type for GaN was observed.

Moving Compacton-like Kink in a Purely Anharmonic Lattice with Symmetric On-Site Potential
XIA Qing-Lin, JIANG Dong-Chu
Chin. Phys. Lett. 2003, 20 (1): 105-107 .  
Abstract   PDF(pc) (274KB) ( 284 )
We study the moving compacton-like kink in the system of a purely anharmonic lattice with symmetric on-site potential by a direct algebraic method. It is found that the localization of the compactons is related to the nonlinear coupling parameter Cnl and the potential barrier height V0 of the double well potential, and the velocity of the propagation of the compacton is determined by the localization parameter q and the potential barrier height V0. Numerical calculation results demonstrate that the compacton is stable when it moves along the lattice chain.
Fabrication of Single Crystalline Silicon on Glass by Smart-Cut Technique
SONG Hua-Qing, SHI Jing, ZHANG Miao, LIN Qing, LIN Cheng-Lu
Chin. Phys. Lett. 2003, 20 (1): 108-110 .  
Abstract   PDF(pc) (421KB) ( 637 )
Single crystalline silicon films are transferred on to a glass substrate by the smart-cut technique, which is based on H+ ions implantation, anodic bonding and layer transfer. Structures of the resulting thin film silicon on glass (SOG) are characterized by transmission-electron microscopy, scanning electron microscopy and Raman spectroscopy. The results show that SOG substrates fabricated by the smart-cut have advantages of steep top Si/glass interface and good monocrystalline Si quality. The Hall-effect measurement indicates that the single crystalline SOG substrates have a better electrical property compared with polycrystalline silicon SOG substrates.

Influence of Mass Transport on Formation of Si-Nanostructures
ZHANG Xiao-Na, LI Chao-Rong, ZHANG Ze
Chin. Phys. Lett. 2003, 20 (1): 111-113 .  
Abstract   PDF(pc) (301KB) ( 429 )
Nanowires-like, condyloid-like and flakes of Si-nanostructures were synthesized by thermal evaporation under different mass transport conditions by changing the ambient pressure. The structural analysis shows that a higher mass transport rate is not favorite for the formation of fine single crystalline nanowires when the substrate placed closely to the thermal vapor source. The higher mass transport rate can induce a lower Si partial pressure near the source and hence results in a lower supersaturation near the substrate. Experimental results reveal that the formation of Si-nanowires is not controlled by mass transport but by surface process. The driving force on the surface is the key factor for the formation of well-crystallized nanowires.
Electronic Structures of the Filled Tetrahedral Semiconductor LiMgN with a Zincblende-Type Structure
LI Hui-Ping, HOU Zhu-Feng, HUANG Mei-Chun, ZHU Zi-Zhong
Chin. Phys. Lett. 2003, 20 (1): 114-116 .  
Abstract   PDF(pc) (394KB) ( 809 )
An ab initio method with mixed-basis norm-conserving non-local
pseudo-potentials has been employed to investigate the electronic structures of LiMgN. The band structure, electronic density of states and charge density contour plot of LiMgN are also presented. By the calculation, we have found that LiMgN with a zinc-blende-type structure was an indirect gap semiconductor, and the value of indirect (Γ - X) energy band gap under the local density approximation was 2.97 eV. In addition, the strong covalent character for Li-N and Mg-N has also been found in LiMgN.
Behaviour of Polariton in a Simple Model
WAN Shao-Long, MA Shuang-Ge, WANG Ke-Lin
Chin. Phys. Lett. 2003, 20 (1): 117-120 .  
Abstract   PDF(pc) (320KB) ( 281 )
Behaviour of a simple model polariton system is restudied. The distribution of phonons in polariton never is sub-Poisson given by computation of the thermal counterpart of the Q parameter and the matrix m(3). The polariton complex as a whole shows non-classical behaviour below a threshold temperature, which depends on the photon-phonon coupling strength, when the distribution of phonons is always classical at any temperature.

Second Bound State of Biexcitons in Quantum Dots
XIE Wen-Fang
Chin. Phys. Lett. 2003, 20 (1): 121-123 .  
Abstract   PDF(pc) (240KB) ( 383 )
The second bound state of the biexcitons in a quantum dot, with orbital angular momentum L = 1, is reported. By using the method of few-body physics, the binding energy spectra of the second bound state of a biexciton in a GaAs quantum dot with a parabolic confinement have been calculated as a function of the electron-to-hole mass ratio and the quantum dot size. The fact that the biexcitons have a second bound state may aid in the better understanding of their binding mechanism.
Electronic Transport in Nanostructures Consisting of Magnetic-Electric Barriers
LU Mao-Wang, ZHANG Li-De, YAN Xiao-Hong
Chin. Phys. Lett. 2003, 20 (1): 124-126 .  
Abstract   PDF(pc) (545KB) ( 475 )
We present a theoretical investigation on the transport properties of the nanostructures consisting of magnetic-electric barriers produced by the deposition, on the top of a heterostructure, of metallic ferromagnetic stripe with an applied voltage. Both the transmission probability and the conductance are found to be greatly dependent upon the applied voltage. When a positive voltage is applied to the stripe, both the transmission probability and the conductance shift towards low-energy region and increase. Conversely, they move towards high-energy direction and reduce for an applied negative voltage.

Preparation and Transparent Property of the n-ZnO/p-Diamond Heterostructure
WANG Cheng-Xin, GAO Chun-Xiao, LIU Hong-Wu, HAN Yong-Hao, LUO Ji-Feng, SHEN Cai-Xia
Chin. Phys. Lett. 2003, 20 (1): 127-129 .  
Abstract   PDF(pc) (313KB) ( 414 )
Heterostructures of an n-type ZnO film/p-type diamond film on the {111} crystalline diamond substrate have been prepared for the first time. The electrodes of the n- and p-type semiconductors are experimentally verified to be ohmic. The diode shows a good rectification characteristic and the ratio of forward current to the reverse current exceeded 200 within the range of applied voltages of -2 to +2 V. The turn-on voltage of the diode is 0.34 V and the highest current is about 5.0 mA as the forward voltage reaches 2 V. Moreover, the diode is optically transparent in the region of 500-700 nm wavelength.

Multi-Rare-Earth Ions Codoped Tellurite Glasses for Potential Dual Wavelength Fiber-Optic Amplifiers
DAI Shi-Xun, YANG Jian-Hu, XU Shi-Qing, DAI Neng-Li, WEN Lei, HU Li-Li, JIANG Zhong-Hong
Chin. Phys. Lett. 2003, 20 (1): 130-132 .  
Abstract   PDF(pc) (379KB) ( 697 )
A novel co-doping method of multi-rare-earth (RE) ions was demonstrated in tellurite glasses for fiber amplifiers. Fluorescence emissions at both 1.53 and 1.63μm communication windows were firstly observed from Er3+/Yb3+/Tm3+-codoped tellurite glasses under a single wavelength pumping at 980 nm. The full width at half maximum of fluorescence at 1.53 and 1.63μm are 55 nm and 50 nm, respectively. This codoping method of three RE ions could be applied to other low photon energy glasses, which would be possibly used for potential dual wavelength fiber-optic amplifiers to broaden the communication windows.
Fluorescence Microscopy of Nanoscale Silver Oxide Thin Films
PAN Xin-Yu, JIANG Hong-Bing, LIU Chun-Ling, GONG Qi-Huang, ZHANG Xi-Yao, ZHANG Qi-Feng, XU Bei-Xue, WU Jin-Lei
Chin. Phys. Lett. 2003, 20 (1): 133-136 .  
Abstract   PDF(pc) (329KB) ( 415 )
The experimental conditions for photoactivated intermittent fluorescence from nanoscale silver oxide were studied with fluorescence microscopy. Strong fluorescence was observed from the Ag2O particles with size of 10-20 nm excited with both blue and green light. We observed the saturation of photoexcitation with blue light and explained the experimental results using the model of agglomeration of silver atoms to form small clusters and the fluorescence of Ag2 and Ag3 clusters.

Colossal Magnetoresistive p-n Junctions of Te-Doped LaMnO3/Nb-doped SrTiO3
LÜ, Hui-Bin, DAI Shou-Yu, CHEN Zheng-Hao, LIU Li-feng, GUO Hai-Zhong, XIANG Wen-Feng, FEI Yi-Yan, HE Meng, ZHOU Yue-Liang, YANG Guo-Zhen
Chin. Phys. Lett. 2003, 20 (1): 137-140 .  
Abstract   PDF(pc) (628KB) ( 678 )
We have fabricated colossal magnetoresistive (CMR) p-n junctions made of Te-doped LaMnO3 and Nb-doped SrTiO3 with laser molecular beam epitaxy. The I-V characteristics of the La0.9Te0.1MnO3/SrNb0.01Ti0.99O3 p-n junctions as a function of applied magnetic field (0-5 T) were experimentally studied in the temperature range 77-300 K. The results indicate that the p-n junction exhibited the CMR behaviour. The magnetoresistance (MR) is positive at 220 K and 300 K, while it displays a negative MR at 77 K. For a positive bias, the MR ratios (ΔR/R0, ΔR = RH-R0) are 7.5% at 0.1 T and 18% at 5 T for 300 K, 5% at 0.1 T and 33% at 5 T for 220 K, -14% at 0.1 T and -71% at 5 T for 77 K. For a negative bias, the MR ratios are 6.3% at 0.1 T and 10.8% at 3 T for 300 K, 5.1% at 0.T and 15% at 3 T for 220 K, -19% at 0.1 T and -72% at 5 T for 77 K. The CMR behaviour of the p-n junction is different from those of the LaMnO3 compound family.
Single-Bubble Sonoluminescence Under Different Driving Pressures
LU Mei-Jun, CHEN Wei-Zhong, JIANG Li-An, LI Sheng-Qiong, WANG Wen-Jie
Chin. Phys. Lett. 2003, 20 (1): 141-143 .  
Abstract   PDF(pc) (389KB) ( 303 )
We experimentally investigate the single-bubble sonoluminescence (SBSL) under different driving pressures. The spectrum of SBSL, pulse shape of light emission and the phase of SBSL are all studied, compared to a sinusoidal driving pressure. The results show that the temperature and the width of the light pulse increase with increasing sound pressure. So does the phase of SBSL emission, which agrees very well with the numerical calculation result. At the same time, a possible method of determining the value of sound pressure was discussed.

Micropolarizer of Ordered Ni Nanowire Arrays Embedded in Porous Anodic Alumina Membrane
PANG Yan-Tao, MENG Guo-Wen, SHAN Wen-Jun, FANG Qi, ZHANG Li-De
Chin. Phys. Lett. 2003, 20 (1): 144-147 .  
Abstract   PDF(pc) (396KB) ( 595 )
A micropolarizer of nickel nanowire arrays within an anodic alumina membrane (AAM) was fabricated by anodization of pure Al and electrodeposition of Ni, respectively. X-ray diffraction, scanning electron microscopy and transmission-electron microscopy reveal that the nanowires are polycrystal and have an average diameter of 70 nm. Spectrophotometer measurements show that the nickel nanowire arrays embedded in the AAM can only transmit polarized light vertical to the wires. An extinction ratio of 25 to 30 dB and an average insertion loss of 1.07 dB in the wavelength range of 1-2.5μm were obtained, respectively. Thus, Ni nanowire/AAM can be used as a wire grid type micropolarizer.

Switching Properties and Phase Transition Mechanism of Mo6+-Doped Vanadium Dioxide Thin Films
XU Shi-Qing, MA Hong-Ping, DAI Shi-Xun, JIANG Zhong-Hong
Chin. Phys. Lett. 2003, 20 (1): 148-150 .  
Abstract   PDF(pc) (338KB) ( 921 )
Using V2O5 and MoO3 powders as precursors, a novel preparation method, i.e., the so-called inorganic sol-gel, is developed to synthesize Mo6+-doped vanadium dioxide (VO2) thin films. The structure, valence state, phase transition temperature and magnitude of resistivity change are characterized by x-ray diffraction, x-ray photoelectron spectroscopy and the four point equipment. The results show that the main chemical composition of doped thin films was VO2, the structure of MoO3 in doped thin films did not change, and the phase transition temperature of doped thin films was obviously lowered with the increasing MoO3 doped concentration, but the magnitude of resistivity change was also decreased. However, so long as MoO3 doped concentration was not more than 5wt.%, the magnitude of resistivity change of doped thin films still reached more 2 orders. The analysis show that MoO3 dissolved in crystal structure of VO2 formed the donor defect MOxv and then reduced the forbidden-band width, which lowered the phase transition temperature. Consequently it was widened applications of the VO2 thin films.
Exact Solution of the Cluster Size Distribution for Multi-polymer Coagulation Process
KE Jian-Hong, LIN Zhen-Quan, WANG Xiang-Hong
Chin. Phys. Lett. 2003, 20 (1): 151-154 .  
Abstract   PDF(pc) (219KB) ( 582 )
We propose a simple irreversible multi-polymer coagulation model in which m polymers consist of multiple components bond spontaneously to form a larger cluster. We solve the generalized Smoluchowski rate equation with constant reaction rates to obtain the exact solution of the cluster size distribution. The results indicate that the evolution behaviour of the system depends crucially on the polymer number m of the coagulation reaction. The cluster concentrations decay as t-m/ (m-1)2, and the typical size S(t) of the m-polymer coagulation system grows as t1/(m-1). On the other hand, the cluster size distribution may approach unusual scaling form in some cases.

Structural and Dynamical Analysis of a Two-Dimensional Dusty Plasma Lattice
HUA Jian-Jun, LIU Yan-Hong, YE Mao-Fu, WANG Long, ZHANG Zhi-He
Chin. Phys. Lett. 2003, 20 (1): 155-157 .  
Abstract   PDF(pc) (447KB) ( 563 )
A two-dimensional dusty plasma lattice in an rf discharge was observed. The structural and dynamical properties were analysed by computing pair correlation function, static structure factor, bond-orientational correlation function and mean square displacement. The bond-orientational correlation function was found to fit into the law of r0.25, and the mean square displacement experienced “ballistic”, “subdiffusive” and “diffusive” regimes, both of which together with the other parameters indicate that the two dimensional dusty plasma stayed at a state between liquid and solid.

A New Silicon-on-Insulator Structure of Metal-Oxide-Semiconductor Field Effect Transistor to Reduce Self-Heating Effect
LIN Qing, ZHANG Zheng-Xuan, ZHU Ming, XIE Xin-Yun, SONG Hua-Qing, LIN Cheng-Lu
Chin. Phys. Lett. 2003, 20 (1): 158-160 .  
Abstract   PDF(pc) (628KB) ( 521 )
A new silicon-on-insulator (SOI) device structure is proposed. This new design provides a new path to reduce the temperature of the channel of SOI metal-oxide-semiconductor field effect transistor (MOSFET). The device has been verified in two-dimensional device simulation. The new structure reduces the self-heating effect of SOI MOSFET and decreases the negative differential transconductance.

Photoeletricity Capability of Imager Detector with Coated Blends of Polymer and Perylene or Coronene
YANG Bing, LI Ying, XIE Ming-Gui
Chin. Phys. Lett. 2003, 20 (1): 161-163 .  
Abstract   PDF(pc) (364KB) ( 495 )
Perylene and coronene have been synthesized with good yield via
the Dields-Alder reaction. They have good photoluminescence properties and could transfer ultraviolet light to visible-light. To find an easy way of making a better ultraviolet charge coupled device, we blended perylene or coronene with polymers. Then, these blends were analysed by the photoluminescence spectrum. The results indicate that the blends have larger fluorescence intensity than pure perylene or coronene. Through spreading these blends on imager detectors, organic imager detectors having good ultraviolet photoelectricity capability were prepared.
Ultrasonic P Wave Velocity and Attenuation in Pyroxenite Under 3.0 GPa up to 1170°C
LIU Wei, DU Jian-Guo, BAI Li-Ping, ZHOU Wen-Ge, GUO Jie
Chin. Phys. Lett. 2003, 20 (1): 164-166 .  
Abstract   PDF(pc) (346KB) ( 474 )
Ultrasonic P wave velocity (VP) and quality factor (QP value, on behalf of attenuation) in pyroxenite were presented as functions of pressures (0.3-3.0 GPa) and temperatures (20-1170°C). The experimental results show that VP and QP depend upon pressure and temperature. VP and QP in pyroxenite increase more rapidly at the pressure 0.3-1.4 GPa than those at 1.4-3.0 GPa. As the temperature rising from 20°C to about 1170°C at the pressure 3.0 GPa, an almost linear decrease up to 11% in VP was observed, and QP drops from 243 at room temperature to 68 at 1170°C with the decrease of 72 %. The experimental data indicate that the pressure and temperature induced fabric changes and frictional sliding and dislocation in pyroxenite play a key role in wave propagation in rocks.
Moist Potential Vorticity and Up-Sliding Slantwise Vorticity Development
CUI Xiao-Peng, GAO Shou-Ting, WU Guo-Xiong
Chin. Phys. Lett. 2003, 20 (1): 167-169 .  
Abstract   PDF(pc) (235KB) ( 466 )
By using the moist potential vorticity equation derived from complete atmospheric equations including the effect of mass forcing, the theory of up-sliding slantwise vorticity development (USVD) is proposed based on the theory of slantwise vorticity development. When an air parcel slides up along a slantwise isentropic surface, its vertical component of relative vorticity is developed. Based on the theory of USVD, a complete vertical vorticity equation is expected with mass forcing, which explicitly includes the effect of both internal forcings and external forcings.

Structure of Callisto and Ice Holes on Its Surface
ZHANG Jian-Hui, CHEN Chu-Xin
Chin. Phys. Lett. 2003, 20 (1): 170-172 .  
Abstract   PDF(pc) (179KB) ( 387 )
The discovery of the induced magnetic field of Callisto that is a satellite of Jupiter has been interpreted as evidence for a subsurface salty liquid-water ocean, so we consider a layered structure of Callisto, i.e., a rock-metal core, an outer layer of ice and a middle layer of ocean. For the rock-metal core we try to indicate how the temperature, pressure and mass density depend on the depth. Due to motion across the magnetic field of Jupiter in a plasma environment, the ice shell of Callisto must be broken down by electric current.
Pulsar Spin-Down by 3P2 Superfluid Neutron with Field Decay
LUO Xin-Lian, PENG Qiu-He, , CHOU Chih-Kang,
Chin. Phys. Lett. 2003, 20 (1): 173-176 .  
Abstract   PDF(pc) (392KB) ( 415 )
To describe pulsar spin-down, we present a simple combined torque model that takes into account both the standard magnetic dipole radiation and the electromagnetic radiation from the 3P2 superfluid vortex neutrons inside neutron star. Using an ordinary exponential model for the magnetic field decay, we derive an analytical formulae for pulsar evolution tracks. The pulsar evolution on the P-P diagram is quite different from that of the standard magnetic dipole radiation model, especially when the superfluid torque or field decay becomes dominant.
52 articles