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Volume 14 Issue 9
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Original Articles
Competition Between Pairing and Anti-pairing Correlations in the Superdeformed Nuclear States in A ~ l90 and 150 Ranges
LIU Yu-xin, SONG Jian-gang, SUN Hong-zhou, WANG Jia - jun, ZHAO En-guang
Chin. Phys. Lett. 1997, 14 (9): 641-644 .  
Abstract   PDF(pc) (245KB) ( 335 )
An approach considering both pairing and anti-pairing correlations in superdeformed (SD) states is proposed. Calculated results show that not only the general changing feature but also the turnover of dynamical moment of inertia with rotational frequency of the first SD band of 192Hg, 194Hg, and 152Dy are well described in the approach. It indicates that there exist competition, even change-over between the anti-pairing and pairing effects in the SD states in A ~ 190 and 150 ranges.

Light Hadrons at Finite Temperature in the Linear Sigma Model
CHEN Hong, LIU Bo, JIANG Huan-qing
Chin. Phys. Lett. 1997, 14 (9): 645-647 .  
Abstract   PDF(pc) (142KB) ( 387 )
The vacuum properties at finite temperature for the linear sigma model are studied by using the effective potential formalism. It is found that the light hadronic masses drop fast with increasing temperature. An extensive scaling behavior of light hadronic masses is observed and is found to follow the scaling law postulated in dense matter.
Influence of First-Order Phase Transition on the Single-Photon Spectra
AI Xiao-bai
Chin. Phys. Lett. 1997, 14 (9): 648-651 .  
Abstract   PDF(pc) (265KB) ( 511 )
A dynamical like-compact-star structure model is presented to treat the first-order phase transition from quark-gluon plasma to hadronic matter. It is found that the influence of latent heat released in phase transition on the single-photon spectra is too evident to be ignored even with the conventional expansion scenario.
Floquet Eigenstate, Phase Space Distribution and Entropy in the Atomic Stabilization Dynamics
XIE Bai-song, CHEN Shi-gang
Chin. Phys. Lett. 1997, 14 (9): 652-655 .  
Abstract   PDF(pc) (228KB) ( 388 )
A simple numerical method is developed to calculate the Floquet eigenstate and the quasienergy; the quantum Wigner function and the Husimi function in phase space in the atomic stabilization dynamics have also been studied Within the Kramers-Henneberger reference frame. The characteristic Wehrl entropy is introduced and used to measure the spreading and ionization of those obtained Floquet eigenstate wave packets.

Symmetry Reduction and Rotational Re-quantization of Symmetric Top Molecules at Local Mode Limit
CHENG Ji-xin, WANG Xiao-gang, LIN Hai, ZHU Qing-shi
Chin. Phys. Lett. 1997, 14 (9): 656-659 .  
Abstract   PDF(pc) (226KB) ( 581 )
The (400) stretching overtone band of AsH3 has been observed near 8029.0 cm-1 and analyzed in both symmetric and asymmetric top models. The results indicate that the dynamical symmetry of the (400) local mode state has reduced to that of an asymmetric top and the rotational energy levels can be assigned by a set of quantum numbers J, Ka, and Kc.
The (e, 2e) Spectra of Argon
FAN Xiao-wei, ZHOU Shao-jie, ZHANG Qing-Xiang, ZHANG Wen-xin, PANG Wen-ning, LAI De-shi, WEI Jing-jing, ZHU Wei-bin, WANG Xiao-dong, DENG Jing-kang, WANG Yan, GAO Nai-fei, ZHENG Yen-you, CHEN Xue-jun
Chin. Phys. Lett. 1997, 14 (9): 660-662 .  
Abstract   PDF(pc) (115KB) ( 471 )
Accurate measurements of the binding energy spectrum and momentum distribution of argon areperformed using the high resolution (ΔE = 1.4 eV, Δp = 0.1 a.u.) energy multichannel (e, 2e) spectrometer (θ1 = θ2 = 45°,  = 0°- ±30°) built recently in our laboratory. Detailed satellite structure of argon has been observed. Good agreement can be found between the experimental data and the theoretical calculations performed using Hartree- Fock method with the different basis sets and configuration interaction method.

Photoionization Time-of-Flight Mass Spectra of Aluminum Clusters-Associated Complexes
NI Guo-quan, ZHOU Ru-fang, ZHAI Hua-jin, WANG Yu-zhu
Chin. Phys. Lett. 1997, 14 (9): 663-666 .  
Abstract   PDF(pc) (266KB) ( 394 )
Using a laser vaporization/pulsed molecular beam source, photoionization time-of-flight mass spectra of bare aluminum clusters Aln (n up to larger than 70) and of carbon-, oxygen-, and hydrogen-adducted aluminum clusters-associated complexes are detected. The cause of the observed odd-even alternation in reactivity of Aln and the formation mechanism of the informative products are discussed.
Observation of High-Order Femtosecond Solitons in a Self-Mode-Locked Ti:Sapphire Laser
ZHANG Wei-li, WANG Qing-yue, CHAI Lu, XING Qi-rong, K. M. Yoo
Chin. Phys. Lett. 1997, 14 (9): 667-670 .  
Abstract   PDF(pc) (229KB) ( 400 )
The N = 3 femtosecond solitonlike pulses are observed directly in a self-mode-locked Ti:sapphire laser as well as even higher-order solitonlike pulses for the first time. When the laser is operating in a stable train of mode-locked pulses, the periodic pulse train appears by only varying the intracavity dispersion. The soliton period with N = 3 corresponds to a cavity round trip number of 164.
Direct Approach Based on the Separation of Variables for the Soliton Study of Perturbed Sine-Gordon Equation
YAN Jia-ren, TANG Yi, CHEN Zhen-hua
Chin. Phys. Lett. 1997, 14 (9): 671-674 .  
Abstract   PDF(pc) (163KB) ( 421 )
A new direct approach based on the separation of variables for the study of soliton perturbations is developed. As an example, the effects of perturbation on a soliton (kink), i.e., both the time-dependence of soliton parameters and the first-order correction are derived for perturbed sine-Gordon equation. Our approach is very concise and easy to understand, and it can be extended directly to deal with other nonlinear evolution equations.

Fiber Optic Moiré Interferometer
YUAN Li-bo
Chin. Phys. Lett. 1997, 14 (9): 675-677 .  
Abstract   PDF(pc) (172KB) ( 500 )
A novel fiber optic moiré interferometer has been developed and demonstrated. A He-Ne laser and three high birefringence fibers were used to configurate a fiber optic interferometer. The moiré fringe patterns formed by the interferometer depend on the arrangement of three fiber ends. The experiment results and the intensity distribution function of the interference patterns are given.
Nonlinear Description of Stimulated Raman Scattering and the Corresponding Four-Wave Process
WANG Shan-cai, HU Xi-wei
Chin. Phys. Lett. 1997, 14 (9): 678-680 .  
Abstract   PDF(pc) (178KB) ( 422 )
Nonlinear behaviors of the stimulated Raman scattering and the corresponding four-wave process ( ω0 → ωs + ωpl + ωp2) are discussed. The analytic and numerical solutions of the coupling equations which count the decay of the pump wave have been given. The difference between three-wave and four-wave parameter processes is also indicated.
Effect of Nitrogen and Hydrogen on the Crystallization of Nanocrystalline Silicon Nitrogen Films
HAN Wei-qiang, HAN Gao-rong, FAN Shou-shan, GU Bing-lin
Chin. Phys. Lett. 1997, 14 (9): 682-685 .  
Abstract   PDF(pc) (244KB) ( 391 )
Hydrogenated nanocrystalline silicon nitrogen (nc-SiNx:H) films were prepared by rf glow discharge of gas mixture of silane (SiH4) and nitrogen (N2) diluted heavily by hydrogen (H2). The effect of the gas volume ratios Xg of (SiU4 +N2)/H2 and XN) of N2/SiH4 on the crystallization and composition of films is described. The growth process and crystallization mechanism of nc-SiNx:H films are discussed in detail.
Extremely Narrow Sb Delta-Doped Epitaxial Layer Characterized by X-Ray Reflectivity
JIANG Zui-min, XIU Li-song, JIANG Xiao-ming, ZHENG Wen-li, LU Xue-kun, ZHU Hai-jun, ZHANG Xiang-jiu, WANG Xun
Chin. Phys. Lett. 1997, 14 (9): 686-689 .  
Abstract   PDF(pc) (244KB) ( 367 )
An Sb delta doping layer in silicon is grown at the temperature of 300°C by silicon molecular beam epitaxy and characterized by the small angle x-ray reflectivity measurement using synchrotron radiation beam. The oscillations of the reflectivity caused by dopant Sb at Q as large as 14.5 are detected. Simulation of this curve as a whole shows that the total amount of dopant Sb is 0.15 monolayer and is restricted to two atomic layers. An extremely narrow Sb delta doping structure without Sb segregation is thus obtained at the growth temperature of 300°C as verified by the experiment.
Metalorganic Chemical Vapor Deposition of GaAs on Si Substrate Prepared by Room Temperature Chemical Cleaning Treatment
YIN Min, LOU Li-ren, FU Zhu-xi
Chin. Phys. Lett. 1997, 14 (9): 690-693 .  
Abstract   PDF(pc) (194KB) ( 333 )
A new method for metalorganic chemical vapor deposition (MOCVD) of GaAs on Si substrates is developed. Instead of the usual high temperature surface cleaning treatment for Si substrate, the new method uses room temperature HF vapor polishing in the preparation chamber in the MOCVD system as the first step of the growth. Single crystal GaAs layers with mirror-like surfaces were obtained.
Effect of Interchain Coupling on Quantum Lattice Fluctuation and Fluctuation Induced Interchain Order Transition in Trans-polyacetylene
ZENG Shang-you, RAO Xue-song, WU Chang-qin, SUN xin
Chin. Phys. Lett. 1997, 14 (9): 694-697 .  
Abstract   PDF(pc) (264KB) ( 411 )
Based on the modified Su-Schrieffer-Heeger Harniltonian and by adding the interchain hopping term, we consider the effect of interchain coupling on quantum lattice fluctuation in trans-polyacetylene. It has been found that the interchain coupling does not always weaken quantum lattice fluctuation. After overcoming a barrier of 1 eV or so, the quantum lattice fluctuation can induce a transition of interchain order. The physical meaning of these features is discussed.
Cooper Pairing Near the Boundary in the -U Hubbard Model
XU Yuan, YAN Xin-zhong
Chin. Phys. Lett. 1997, 14 (9): 698-700 .  
Abstract   PDF(pc) (159KB) ( 351 )
The Cooper pairing near the boundary of a superconductor is analyzed by using the linear-response theory The system is described by the square lattice (t, -U) Hubbard model occupying half space. At half filling, the pairing also corresponds to the antiferromagnetic ordering in the repulsive Hubbard model. The numerical result clearly shows that, at weak to intermediate coupling (U/t ≤ l), the boundary exerts strong influence on the order parameter; the weaker the coupling, the deeper the order parameter is suppressed near the boundary. The present scheme is valid in the whole temperature regime of Cooper pairing.

Field and Current Distribution in Superconducting Film Under Partial Field Penetration
XU Xiao-nong, SUN Ai-min, DING Shi-ying, JIN Xin, YAO Xi-xian, YAN Shao-lin, WEN Hai-hu
Chin. Phys. Lett. 1997, 14 (9): 701-704 .  
Abstract   PDF(pc) (217KB) ( 589 )
Using finite-element analysis in a self-consistent way with the self-field of the current considered for superconducting thin film, the field and current distributions under partial field penetration are calculated based on the field dependent critical current density function. The field penetrated depth is non-linear with the applied field. Due to the limited resolution of the vibrating sample magnetometer (VSM), the full penetrated field measured by VSM may be much smaller than its actual value.
Study of Cr6+ in Water by Surface Enhanced Raman Scattering
HUANG Ya-bin, YU Xiao-hong, ZHANG Wei-feng, MO Yu-jun
Chin. Phys. Lett. 1997, 14 (9): 705-707 .  
Abstract   PDF(pc) (164KB) ( 432 )
Cr6+ in K2Cr2O7, (NH4)2Cr2O7, and K2CrO4 aqueous solution showed the same new strong band of 794cm-1 in surface enhanced Raman scattering (SERS) by using SERS silver substrates. This new feature could be assigned to a surface complex of silver and Cr6+, for instance Ag2CrO4. The feature of 794cm-1 could be a fingerprint band for detecting pollutant Cr6+ in water from SERS by using the SERS active substrate of silver.
Optical Study of Bandedge Blue-Shift in AlGaN/GaN Double Quantum Wells
YANG Kai, SHEN Bo, ZHANG Rong, ZHOU Yu-gang, CHEN Zhi-zhong, CHEN Peng, ZHENG You-dou, HUANG Zhen-chun
Chin. Phys. Lett. 1997, 14 (9): 708-711 .  
Abstract   PDF(pc) (233KB) ( 519 )
Optical properties of AlGaN/GaN double quantum wells grown by metalorganic chemical vapor deposition are investigated. The wide-angle and small angle x-ray diffraction spectra show high crystalline quality of the sample. Optical transmission and cathodoluminescence spectra exhibit that there is a blue shift of the energy bandedge in the AlGaN/GaN double quantum wells comparing to that of bulk GaN. The experimental data are compared to theoretical calculation based on the finite square well model and a confined particle transitions are identified. The observed energy shift which differs from calculated values of ground state electron to heavy hole transition is attributed to strain in the AlGaN/GaN system.
Identification and Rutherford Backscattering Measurement of MeV Carbon Cluster Ions
WANG Xue-mei, LU Xi-ting, XIA Zong-huang, SHEN Ding-yu, ZHENG Tao, ZHAO Qiang, ZHAO Zi-qiang
Chin. Phys. Lett. 1997, 14 (9): 712-714 .  
Abstract   PDF(pc) (122KB) ( 458 )
The MeV carbon cluster ions provided by 1.7 MV tandem accelerator were identified and Rutherford backscattering spectra of MeV carbon cluster ions on the gold film were measured with silicon surface barrier detector.
Antimatter Domain and X-ray Background
XU Chong-ming, WU Xue-jun
Chin. Phys. Lett. 1997, 14 (9): 715-718 .  
Abstract   PDF(pc) (254KB) ( 405 )
This paper suggests an effective method to detect the antimatter domain by means of x-ray background radiation if the universe is Symmetric. The photons produced by the annihilation of electron-positron and proton-antiproton on the last scattering surface are considered. A possible observational figure is described also.
Comment on “Exact Solution of Persistent Currents in One-Dimensional Mesoscopic Rings with Consideration of Electron-Phonon Coupling”
ZHOU Yi-chang, FANG Yi-zhong
Chin. Phys. Lett. 1997, 14 (9): 719-719 .  
Abstract   PDF(pc) (57KB) ( 323 )
Reply to Comment
WANG Ke-lin, WANG Mao-xi
Chin. Phys. Lett. 1997, 14 (9): 720-720 .  
Abstract   PDF(pc) (29KB) ( 522 )

23 articles