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Volume 9 Issue 11
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Original Articles
Revised Effective Theory Including Strong CP Violation
WU Dandi
Chin. Phys. Lett. 1992, 9 (11): 565-568 .  
Abstract   PDF(pc) (0KB) ( 219 )
In this paper we provide a compact version of the effective theory of pseu-doscalar mesons. Our way of representing the θ-term is different from previous ones in the literature. Yet no gauge fields appear in this model, it bears many other underotood features of the underlying QCD, such as large ŋ mass and, if θ≠0, non-zero ŋ→ 2π decay amplitude.
Stochastic Dynamics of Langmuir Wave Fields
ZHOU Cangtao, HE Xiantu(X. T. He)
Chin. Phys. Lett. 1992, 9 (11): 569-572 .  
Abstract   PDF(pc) (191KB) ( 396 )
The chaotic behavior of a cubic-quintic nonlinear Schrődinger equation has been discussed numerically. It is shown that the quintic Hamiltonian perturbation leads to the integrability of system broken down.
Cumulant Expansion in Intermediate Coupling Region in U(l) Lattice Gauge Theory
ZHENG Xite, LI Yuliang, LEI Chunhong
Chin. Phys. Lett. 1992, 9 (11): 573-576 .  
Abstract   PDF(pc) (193KB) ( 545 )
Determining the parameters in the i-th order approximation in the cumulant expansion from the requirement that the correction to the zeroth order approximation is zero or the smallest, we show in the example of calculating the Polyakov line < L > of U(1) gauge model at finite temperature with NT = 1-to 5-th order that the expansion works well not only in the strong and weak coupling regions, but also in the intermediate coupling region except the very vicinity of the phase transition point. The calculated < L > is in agreement with Monte Carlo simulations.
Sub-Barrier Fusion Coupled-Channels Calculations for 16O + 16,18O
LIU Guimin, FU Deji*, CHENG Xiaowu
Chin. Phys. Lett. 1992, 9 (11): 577-580 .  
Abstract   PDF(pc) (200KB) ( 453 )
A simple version of coupled channels approach is generalized to the light system 16O + 16,18O for subbarrier fusion study. It shows that the contribution of the inelastic channel of 2+1 state in 18O is small, while neutron-pair transfer reaction channel of vanishing Q-value is required to explain the trend of the existing low-energy fusion data.
Electronic Structure of CBN Ball Within Tight-Binding Approximat ion
LIU Jingnan, HUANG Mingwei, GU Binglin
Chin. Phys. Lett. 1992, 9 (11): 581-584 .  
Abstract   PDF(pc) (148KB) ( 408 )
Using a tight-binding approximation, we have calculated the electronic structure of the suggested CBN ball created from buckyball C60 in which 48 carbon atoms are replaced with 24 boron atoms and 24 nitrogen atoms.

A Model on Understanding Atomic Coherence in Lasing Without Inversion
LUO Zhenfei, XU Zhizhan
Chin. Phys. Lett. 1992, 9 (11): 585-588 .  
Abstract   PDF(pc) (182KB) ( 458 )
A laser model which may operate in the absence of population inversion is proposed. It is found that the realization of lasing without inversion in this model is due to the change of noninversion condition along with the creation of atomic coherence, instead of a coherence-term-induced gain enhancement.

Experimental Evidence of Radiation Amplification Without Population Inversion in Sodium Atoms
GAO Jinyue, GUO Chuan*, JIN Guangxu, GUO Xinzhen, WANG Qingwen, ZHANG Hanzhuang, ZHAO Jian, JIANG Yun, WANG Dezhong, JIANG Dongmei
Chin. Phys. Lett. 1992, 9 (11): 589-592 .  
Abstract   PDF(pc) (184KB) ( 446 )
We have demonstrated a radiation amplification without population inversion in sodium according to a four-level model, which was recentlyproposed by Nor-ducci et al. The amplified radiation signal at 589.0nm has been observed when an intense coherent driving field at 589.6nm was on and an incoherent pumping process from the ground state 3S1/2 to 3P3/2 excited state was operating.
Stimulated Emission Originated from Collision of Long Life Zn
LI Zhaolin, CHENG Bingying, ZHU Junkong*, ZHANG Daozhong
Chin. Phys. Lett. 1992, 9 (11): 593-596 .  
Abstract   PDF(pc) (210KB) ( 400 )
Under the resonant excitation of Zn atomic 4p3P1 state a strong stimulated emission at 481.0nm is produced, which corresponds to the transition between 5s3S1 and 4p3P2 of Zn. If N2 molecular gas is used as buffer gas instead of rare gas He or Ar, the stimulated emission may be enhanced by several orders of magnitude. The dependences of intensity on density of atomic Zn and N2 pressure are studied experimentally. The mechanism which causes population inversion is propased.
Two Kinds of Deep Hole-Traps in Bi4Ge3O12 Crystal
FENG Xiqi, CHENG Chaoyang, YIN Zhiwen, M. R. Khamlary*, P. D. Townsend*
Chin. Phys. Lett. 1992, 9 (11): 597-600 .  
Abstract   PDF(pc) (191KB) ( 541 )
This paper presents the thermoluminescence (TL) and the absorption spectra of a series of doped Bi4Ge3O12(BGO) crystal irradiated by ultraviolet light. By the representation of Fe : BGO and Mn : BGO, the formation mechanism of two kinds of deep TL traps was discussed, and also their association with the stability of color center.

Resonant Raman Scattering Studies of the Ion-Beam-Irradiated Polyimide Films
XU Dong, XU Xinglong, DU Gendi, ZOU Shichang
Chin. Phys. Lett. 1992, 9 (11): 601-604 .  
Abstract   PDF(pc) (181KB) ( 470 )
Experimental evidence has been obtained to support the applicability of the conduction mechanism, namely two-phase model proposed by Sheng [Phys. Rev. Lett. 31 (1973) 44], for the polyimide films subjected to high-energy-ion irradiation. The spectra obtained by resonant Raman spectroscopy can be well interpreted in terms of this model.
Double-Crystal x-Ray Diffraction Study on Ta/Al Multilayers
XIU Lisong, YUAN Xiangyang, WU Ziqin, JIANG Shusheng*, HU An*, ZHAO Jiyong**, JIANG Jianhua**
Chin. Phys. Lett. 1992, 9 (11): 605-608 .  
Abstract   PDF(pc) (213KB) ( 774 )
Double-crystal x-ray diffraction has been used to measure the rocking curve of Ta/Al multilayers. The diffraction profiles of the multilayers are different. Besides the normal profile, two kinds of distorted profiles have been found. The simulations show that the deformed profiles of the peaks are caused by the imperfect periodicity (e.g. systematic period deviation and coexistence of two slightly different periods) in the multilayers.
Spectral Structure and Gap-Labeling Properties for a New Class of One-Dimensional Quasilattices
HUANG Xiuqing*, LIU Youyan**
Chin. Phys. Lett. 1992, 9 (11): 609-612 .  
Abstract   PDF(pc) (183KB) ( 565 )
A new class of 1D quasiperiodic lattices, for which the substitution rules are B→BA, and A→BAB, has been studied in several aspects. The high-dimensional projection method for obtaining the quasilattice is presented. A multifractral spectral behavior and gap fabeling properties have been found, which display the perfect quasiperiodicity of the studied model.
Field and Temperature Dependence of Susceptibility of Single Crystal Bi2Sr2CaCu2O8
YU Zheng, DING Shiying, ZENG Zhaoyang, SHI Kexin, YAO Xixian, YANG Guang*, ZHAO Zhongxian*, WANG Hong**, WANG Zhuo**
Chin. Phys. Lett. 1992, 9 (11): 613-616 .  
Abstract   PDF(pc) (175KB) ( 467 )
Susceptibility measurements on Bi2Sr2CaCu2O8 single crystals do reveal field-induced-suppression of sharp phase transition. No apparent anisotropy of the susceptibility was observed when magnetic field was applied along the three main directions a, b and c. The three dimensional isotropic fluctuation diamagnetism theory is proposed to explain our experimental finding of isotropic susceptibility. In a wide range of magnetic field, the temperature dependence of susceptibility does not show any obvious change in its character when the sample enters into expected vortex-lattice state from vortex-liquid state.
On Magnetocrystalline Anisotropy of Sm2Fe17Nx Compounds
XU You, BA Tu*, LIU Yinglie**
Chin. Phys. Lett. 1992, 9 (11): 617-620 .  
Abstract   PDF(pc) (222KB) ( 317 )
The effect of the nitrogen on the magnetocrystalline anisotropy of the Sm-sublattice in Sm2Fe17Nx compounds has been calculated with the single ion crystal field model. The effects of the nitrogen atoms at different interstitial sites on the anisotropy of the rare earth sublattice have been discussed.
Decomposition of C70 and C60 Under Laser Irradiation Monitored by Raman Spectroscopy
CHENG Guangxu, ZANG Wencheng, YANG Ping, WANG Wennai, GU Gang, DOU Youwei, FENG Duan
Chin. Phys. Lett. 1992, 9 (11): 621-622 .  
Abstract   PDF(pc) (118KB) ( 327 )
The degradation of C60 in organic solution by light has been reported by Taylor et al. [Nature, 351 (1991)277]. The powders of the mixture of C60 and C70 prepared by arc heating ofgraphite electrodes in the environment of He gas was not to be stable with respect to intense irradiation of argon laser (488.0nm), as monitored by Raman spectrascopy, C70 is found to be first decomposed into fragmentary graphite, then C60 followed suit. It is interesting to note that besides graphite, some traces of diamond-like structure are shown confirming some speculations of Mackay [Nature, 352 (1991) 762]
Renormalization Group on the Aperiodic Hamiltonian
YAN Xiaohong, YOU Jianqiang, YAN Jiaren, ZHONG Jianxin
Chin. Phys. Lett. 1992, 9 (11): 623-625 .  
Abstract   PDF(pc) (150KB) ( 396 )
We present the renormalization group of the generalized Fibonacci lattices associated with the aperiodic sequences as constructed by the inflation rule: {A,B} →{AnBm,A}, in which m and n are positive integers. The derived renormalization group consists of 2n(n+ m - 1) + 1 basic renormalization-group Mtransformations. By suitable combinations of these basic transformations, the local electronic properties of the generalized Fibonacci lattices can be exactly obtained.

16 articles