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Volume 15 Issue 1
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Original Articles
Derivation of Tilde Rules in η-ξ Spacetime
ZUO Jian, GUI Yuan-xing
Chin. Phys. Lett. 1998, 15 (1): 1-2 .  
Abstract   PDF(pc) (146KB) ( 386 )
The M operation is introduced in η-ξ spacetime to derive the tilde rules in thermo field dynamics (TFD). This leads to an explanation of the tilde system in TFD as the system in region II of η-ξ spacetime.

Feature of Motion Around D-stars
LI Jia-mu, LI Xin-zhou,
Chin. Phys. Lett. 1998, 15 (1): 3-4 .  
Abstract   PDF(pc) (149KB) ( 325 )
The motion of test particles around D-stars is investigated by Hamilton-Jacobi method. There may exist bound orbits under certain conditions. The trajector with periastrons at large r are Keplerian in form, except for the periastron shift. The trajectory with periastrons at small r, differ markedly from Keplerian orbits. The radius of the most tightly bound is found.
Splitting of One-Phonon Coupling States in the Weakly Coupling Model
LONG Gui-lu, RUAN Dong, ZHANG Wei-lin, ZHU Sheng-jiang
Chin. Phys. Lett. 1998, 15 (1): 5-7 .  
Abstract   PDF(pc) (205KB) ( 383 )
The splitting of one-phonon coupling states in the weakly coupling model for odd-A nuclei is studied. Matrix elements are given explicitly, and an analytical expression for the energy levels is given in a perturbation approach. An application is given to 93Nb and 51V. A comparison between the weakly coupling model and the shell model treatment for 51V is discussed.
Measurement of the 27AI(n, 2n)26A1 Cross Section Using Accelerator Mass Spectrometry
ZHAO Qiang, LU Xiang-yang, GUO Zhi-yu, SHI Zhao-min, WANG Jian-jun, LIU Ke-xin, LI Bin, LI Kun, CHEN Jia-er, LU Han-lin
Chin. Phys. Lett. 1998, 15 (1): 8-9 .  
Abstract   PDF(pc) (178KB) ( 398 )
The 27AI(n, 2n)26AI cross section is of great interest for the waste disposal assessment of fusion reactor materials and fusion research. By the technique of accelerator mass spectrometry, we have measured the 26AI/27AI ratio of AI2O3 powder samples which were irradiated by a neutron beam. The neutron reaction cross section for 27AI(n, 2n)26AI in the energy range of 14.8-14.9MeV are deduced.

On Refinement of Quark-Gluon Plasma Signal in Ultra-Relativistic Heavy Ion Collisions
LIU Feng, LIU Lian-shou
Chin. Phys. Lett. 1998, 15 (1): 10-12 .  
Abstract   PDF(pc) (226KB) ( 490 )
The relation between the formation of a unique system and the upward-bending parameter a of 2-D(η, ψ)lnFq vs InM in relativistic heavy-ion collisions is discussed. It is argued that the correlation between the value of upward-bending parameter a for individual events and the value for the same events of some other quantity, e.g.,K/π ratio, commonly used as quark-gluon plasma signal can be utilized to increase the reliability of this signal.
Rotational Effect of Intermediate Mass Fragments for 40Ar + 159Tb Reaction at 30 MeV/Nucleon
HE Zhi-yong, LI Zu-yu, DUAN Li-min, ZHANG Bao-guo, JIN Gen-ming, DAI Guang-xi, FU Yan-biao, WANG Hong-wei, WANG Su-fang
Chin. Phys. Lett. 1998, 15 (1): 13-15 .  
Abstract   PDF(pc) (245KB) ( 426 )
The in-plane and out-of-plane emissions of light charged particles and intermediate mass fragments were measured for 40Ar + 159Tb collisions at 30 MeV/nucleon. An in-plane enhancement was observed for mid-rapidity light particles and fragments, indicating that a rotational effect exists in this reaction system. This enhancement increased with mass for light particles with Z≤2, but became nearly constant values for fragments with Z≥3. This enhancement was observed to increase strongly with increasing impact parameter.

Time-Dependent Quantum Dynamics Study of Reactive Scattering of the H + O2 Involving Long-Lived Resonances
ZHANG Yi-ci, ZHANG Yan-bing, ZHAN Li-xin, ZHANG Shao-long, ZHANG Dong-hui, John. Zhang Zeng-hui
Chin. Phys. Lett. 1998, 15 (1): 16-18 .  
Abstract   PDF(pc) (175KB) ( 427 )
A time-dependent quantum wave packet calculation for the combustion reaction H + O2 using double many-body expansion IV potential energy surface was studied. The resonance-like structures of probabilities together with the cross section and rate constant results are given.
Isotope Effect in Collision Between Helium Atom and Hydrogen Molecule
YANG Xiang-dong, ZHANG Ji-yan, JlNG Fu-qian
Chin. Phys. Lett. 1998, 15 (1): 19-20 .  
Abstract   PDF(pc) (158KB) ( 333 )
Rotationally inelastic He-H2, D2, T2 collision was studied quantum-mechanically. Converged cross sections were calculated by using the close coupling method for relative kinetic energies of 0.01 to 0.54 eV. Born-Oppenheimer approximation was employed to determine the potential surface of He-D2, He-T2, and He-H2. Careful comparison between the cross sections of the isotopically substituted systems was carried out, and the regular changes of the total cross sections of the isotopically substituted He-H2 colliding systems were obtained.
Structure and Transmission Spectra for Colloidal Crystals with Silica Spheres
MEI Dong-bin, DONG Peng, LI Hong-qiang, CHENG Bing-ying, ZHANG Dao-zhong
Chin. Phys. Lett. 1998, 15 (1): 21-23 .  
Abstract   PDF(pc) (239KB) ( 533 )
An ordered colloidal structure of SiO2 spheres of 0.33μm diameter has been formed in distilled water. It is a face-centered cubic structure with a lattice constant of 0.54μm and a volume fraction of 0.48, as determined by the Kossel rings analysis. The light transmission in the [111] direction exhibited a dip located at 11600cm-1. A plane wave expansion method is used to calculate the lowest gap at the L point. The gap center coincides quite well with the measured transmission dip.
A New Method for Phase Retrieval in the Optical System
CONG Wen-xiang, CHEN Nan-xian, GU Ben-Yuan
Chin. Phys. Lett. 1998, 15 (1): 24-26 .  
Abstract   PDF(pc) (197KB) ( 633 )
In this letter, a new recursive algorithm to implement phase retrieval from two intensities in the two-dimensional Fourier transform domain is presented. In terms of the cascading property and additivity of the order of the fractional Fourier transform, a set of convolution equations is exactly derived. Applying recursive algorithm, these equations can be easily solved. This approach simplifies significantly computational manipulations comparing with conventional iterative algorithms and does not need initial phase distribution.
Nonresonant Optical Nonlinearities of Surface Chemically Modified ZnO Composite Nanoparticles
WANG Rong-yao, WU Xiao-chun, ZOU Bing-suo, WANG Li, WU Peng-fei, LIU Shao-mei, WANG Jin-guo, XU Ji-ren
Chin. Phys. Lett. 1998, 15 (1): 27-29 .  
Abstract   PDF(pc) (221KB) ( 604 )
With surface chemical modification, we have obtained core-shell structure ZnO nanoparticles. The nonresonant third-order nonlinear optical refraction of this new composite material was found to be -3.8 x 10-l0 esu by Z-scan measurements with a femtosecond pulsed laser. The ultrafast nonlinear response time ~250 fs measured by time-resolved pump-probe techniques suggests that the nonlinearity of this new material originates mainly from a rapid electronic polarization process or virtual process such as the optical Stark effect.
Ultrafast Third-Order Optical Nonlinearity of Organic Solvents Investigated by Subpicosecond Transient Optical Kerr Effect
GONG Qi-huang, LI Jian-liang, ZHANG Tie-qiao, YANG Hong
Chin. Phys. Lett. 1998, 15 (1): 30-31 .  
Abstract   PDF(pc) (157KB) ( 806 )
A femtosecond optical Kerr effect experiment has been used to study the dynamic process of third-order optical nonlinearity for organic solvents acetone, acetonitrile, alcohol, benzene, chloroform, dichlomathane, dimenthyl-sulfoxande, dioxane, ethanol, and methanol, etc. The nonlinear refractive index for the solvents at femtosecond time scale was measured.
Measurement of the Optical Coherence of a Femtosecond Pulsed Laser by Shearing Interferometry with a Double-Frequency Grating
MING Hai, QIAN Jiang-yuan, XIE Jian-ping, A. B. Fedotov, X. Xiao, M. M. T. Loy
Chin. Phys. Lett. 1998, 15 (1): 32-34 .  
Abstract   PDF(pc) (252KB) ( 485 )
Shearing interferometry of an ion-etched holographic double-frequency grating is used to measure the optical coherence of femtosecond pulsed lasers. The experimental results show that the optical coherence of the femtosecond light beam is not only related to the spectral width and size of the light source but is also related to the pulse duration and mode-locked laser state. The results of theoretical analysis and numerical calculation are also given. Application of this research is also discussed.

Poloidal Flow Destabilized by Electron Cyclotron Resonant Heatingin Collision Tokamak Plasmas
LIU Cai-gen, QIAN Shang-jie
Chin. Phys. Lett. 1998, 15 (1): 35-37 .  
Abstract   PDF(pc) (212KB) ( 580 )
The production of the poloidally sheared flow during electron cyclotron resonant heating (ECRH) in the collisional tokamak plasmas, which refers to the edge region, is studied. Based on the linearized kinetic drift equation and the fluid equations including the density perturbation term driven by rf waves, the criterion of the destabilization of the poloidal plasma rotation is analytically derived. It is shown that the edge poloidal plasma rotation can be destabilized during ECRH in the present rf power level.
Influence of the Nongyrotropy on the Gyrotropic Ring Instability
CAO Jin-bin, WANG Xue-yi, CAI Chun-lin
Chin. Phys. Lett. 1998, 15 (1): 38-40 .  
Abstract   PDF(pc) (190KB) ( 430 )
The instability driven by the nongyrotropic newborn ions is studied for oblique propagation. The results show the influence of nongyrotropic on the gyrotropic ring instability decreases when the propagation angle increases. The growth rate in the case of nongyrotropic is smaller than that in the case of gyrotropic. The nongyrotropic also breaks the symmetry of the propagation of the waves in the plane perpendicular to the ambient magnetic field.
A Novel Sterilization Method Using Pulsed Discharge Plasma
WANG Xi-lu*, Akira Mizuno, Shijin Katsura
Chin. Phys. Lett. 1998, 15 (1): 41-42 .  
Abstract   PDF(pc) (172KB) ( 396 )
Pulsed discharge plasma(PDP) has been used to kill bacteria and the curves of the survival rate of bacteria against treatment time are obtained. Irreversible structural change in the cell membrane is caused by PDP and the cell is thus killed. The sterilization mechanism is analyzed.

Local Structure Determination of Mn2+-Doped Fluoride Crystals by Superhyperfine Splitting Measurements
ZHAO Min-guang
Chin. Phys. Lett. 1998, 15 (1): 43-45 .  
Abstract   PDF(pc) (170KB) ( 517 )
A procedure is presented for the calculation of the Mn2+-F- bond length from the superhyperfine constants measured by magnetic resonance experiments. With the present technique it is possible to detect the variation of the bond length, ΔR, down to 0.01 Å. The technique is sensitive enough to determine the bond length R and its variation ΔR experienced when pressure or temperature changes.
Studies on Lead Tungstate Crystal
LIU Feng-zhen, HAN Jian-ru, MAN Chang-feng, CHEN Huan-chu, HE Mao
Chin. Phys. Lett. 1998, 15 (1): 46-47 .  
Abstract   PDF(pc) (184KB) ( 356 )
The growth of lead tungstate (PWO) single crystals and their luminescence properties such as light yield, scintillation decay time, and transmittance were reported. The colourless PWO single crystal has been obtained by using the presyntheses powder. Ba, Nb, and Mg ions were doped in the crystals and the Ba-doped crystal has a relatively short decay time. Annealed crystal was found having a better transmission spectrum than that of unannealed one.

A Comparative Study of Defects and Growth in Organic Crystal Family of Hydrogen Phthalates
GUAN Tie-tang, ZHAO Qing-lan, LI Yuan-zhong, HUANG Yi-sen
Chin. Phys. Lett. 1998, 15 (1): 48-49 .  
Abstract   PDF(pc) (261KB) ( 339 )
The organic crystals of potassium hydrogen phthalate (KAP) (or rubidium hydrogen phthalate(RAP)) and thallium hydrogen phthalate(TAP) crystallize out in the same space group of P21ab. The growth morphological change between them has been studied via defective observation and growth theoretical calculation, which indicates that the crystals of KAP and RAP grow through the 2D mechanism and the growth mechanism of (001) faces in TAP changes to defect mechanism. The theoretical results are in good agreement with the experimental ones.

Abnormal Alignment of Misfit Dislocations in In0.52Al0.48As/InxGa1-xAs/In0.52AI0.48As/InP Heterostructure
WU JU, LI Han-xuan, WANG Zhan-guo
Chin. Phys. Lett. 1998, 15 (1): 50-51 .  
Abstract   PDF(pc) (253KB) ( 385 )
It was observed with transmission electron microscopy in the In0.52Al0.48As/InxGa1-xAs/In0.52AI0.48As/InP heterostructure that misfit dislocation lines deviate from the <110> directions at a certain angle depending on the indium content x. Such an abnormal alignment of misfit dislocations is explained in terms of an alloy effect on the formation of single jogs on the misfit dislocations in the interface between the III-V ternary compounds.
Nonlinear Internal Friction Character of Foamed Aluminum
HAN Fu-sheng, ZHU Zhen-gang, WANG Shan-ying, LIU Chang-song
Chin. Phys. Lett. 1998, 15 (1): 52-53 .  
Abstract   PDF(pc) (146KB) ( 324 )
An experiment has been carried out to investigate the damping behavior of foamed aluminum. It was found that foamed aluminum has a significant nonlinear internal friction character, i.e., its damping capacity is amplitude-dependent, and this character tends to be more pronounced with decreasing the density and pore size.
On Interlayer Interaction of 40.8 Free-Standing Films: Experiment and Theory
JIN Anjun Jerry, LIN Bin
Chin. Phys. Lett. 1998, 15 (1): 54-56 .  
Abstract   PDF(pc) (287KB) ( 437 )
Substrate-free films of N-(4-n-butoxybenzylidene-4-n-octylaniline (40.8) show a fascinating interlayer interaction. This interaction significantly affects the next ordering transition, or the second hexatic-B order, upon cooling. The Landau-de Gennes theory is employed to model the effect of the enhanced order by surface-ordering field. Based on this model, it is found that the surface-order penetration depth to be less than one layer.

Observation of the Third Subband Population in Modulation-Doped InGaAs/InAlAs Heterostructure
LI Han-xuan, WANG Zhan-guo, LIANG Ji-ben, XU Bo, LU Mei, WU Ju, GONG Qian, JIANG Chao, LIU Feng-qi, ZHOU Wei
Chin. Phys. Lett. 1998, 15 (1): 57-59 .  
Abstract   PDF(pc) (232KB) ( 412 )
The population of the third (n = 3) two-dimensional electron subband of InGaAs/InAlAs modulation-doped structures has been observed by means of Fourier transform photoluminescence (PL). Three well resolved PL peaks centred at 0.737, 0.908, and 0.980eV are observed, which are attributed to the transitions from the lowest three electron subbands to the n = 1 heavy-hole subband. The subband separations clearly exhibiting the features of the stepped quantum well with triangle and square potentials are consistent with numerical calculation. Thanks to the presence of Fermi cutoff, the population ratio of these three subbands can be estimated. Temperature and excitation-dependent luminescences are also analyzed.
Fine Structure in the Electron Emission Process for Two DX-Like Centers in Sn-Doped AlGaAs
ZHAN Hua-han, KANG Jun-yong, HUANG Qi-sheng
Chin. Phys. Lett. 1998, 15 (1): 60-61 .  
Abstract   PDF(pc) (193KB) ( 312 )
Fine structure in the electron emission process for DX(Sn) centers in AJGaAs has been studied with high resolution Laplace defect spectroscopy. The influence of the different local configuration of AI and Ga atoms around the centers on the electron thermal emissions was observed. An experimental evidence for the microscopic structure of two DX-like centers in Sn-doped AJGaAs is provided.
Electronic Properties of CeCuGa
HOU Yu-rnin, JIN Duo, WANG Yu-peng, LUO Jian-lin, E. Nyeanchi, D. F. Brewer, A. L. Thomson
Chin. Phys. Lett. 1998, 15 (1): 62-64 .  
Abstract   PDF(pc) (195KB) ( 429 )
Specific heat in applied magnetic fields were measured to a low temperature 0.08 K and resistance to 0.5K. The specific heat shows a wide peak at 1 K, and a high value of the electronic coefficient γ (T → 0 ) 1200 mJ/mol.K2 is obtained. The temperature independence of the wide peak in specific heat at 1K in magnetic fields further suggests that the high value γ of CeCuGa is due to Kondo effect.
Effect of Sample Thickness on Magneto-Optic Imaging for Vortex Fully Penetrated Square-Shaped Superconductors
LIU Yun, GAO Zheng-xiang, TAO Jing, HAN Ru-shan
Chin. Phys. Lett. 1998, 15 (1): 65-67 .  
Abstract   PDF(pc) (291KB) ( 393 )
A significant effect of sample thickness on three components of the magnetic flux density distribution on square-shaped superconductor surface is shown, and the critical current density jc of the superconductor from the fully penetrated field μ0H* observed in magneto-optic imaging experiment is calculated.
Mössbauer Study of Catalytically Grown Carbon Nanotube
LI Qun-qing, FAN Shou-shan, HAN Wei-qiang, GAO Nai-fei, WANG Xin-rong
Chin. Phys. Lett. 1998, 15 (1): 68-69 .  
Abstract   PDF(pc) (176KB) ( 380 )
The valence states of iron in iron catalysts, hydrogen reduced catalysts, and catalytically grown carbon nanotubes are determined by Mössbauer spectra, respectively. The results show that the iron exists as Fe, FeO, and α-Fe2O3 in hydrogen reduced catalysts, whereas it exists as Fe-C alloy, FeO, and α-Fe2O3 in the catalysts encapsulated in carbon nanotube. It is postulated that Fe in hydrogen reduced catalysts plays the main role in the formation of catalytically grown carbon nanotube.
Wurtzite Boron Nitride Crystal Growth in the Region of Cubic Boron Nitride Crystal Synthesizing
ZHANG Tie-chen, YU San, LI Dong-mei, GUO Wei-li, GAO Chun-xiao, ZOU Guang-tian
Chin. Phys. Lett. 1998, 15 (1): 70-71 .  
Abstract   PDF(pc) (331KB) ( 919 )
Micro-grains of wurtzite boron nitride(wBN) crystal have been observed in the region of 5.0-7.0 GPa pressure and 1800-2000 K temperature where cubic boron nitride has been synthesized in the presence of a catalyst. The wBN grain size is about 20-30nm. The presence of these micro-grains indicates that the pressure for wBN growth could be lower than that found in the previous work.
Photoluminescence from Erbium-Implanted Silicon-Rich SiO2
LEI Hong-bing, YANG Qin-qing, ZHU Jia-lian, GAO Jun-hua, WANG Hong-jie, WANG Qi-ming
Chin. Phys. Lett. 1998, 15 (1): 72-73 .  
Abstract   PDF(pc) (172KB) ( 335 )
Si-rich SiO2 films were deposited by plasma-enhanced chemical vapor deposition on the silicon substrates, and then implanted with 1 ×1015cm-2 400 keV Er ions. After annealing at 800°C for 5 min, the samples show room temperature luminescence around 1.54 μm, characteristic of intra-4f emission from Er3+, upon excitation using an Ar ion laser.
A Possible Glitch of Gamma-Ray Pulsar Geminga?
ZHANG Shu, LI Ti-pei, WU Mei
Chin. Phys. Lett. 1998, 15 (1): 74-75 .  
Abstract   PDF(pc) (148KB) ( 341 )
Timing analyses of gamma-ray pulsar Geminga were made to check its rotating stability using released energetic gamma-ray experiment (EGRET) data. Phase motions of Geminga were found from EGRET data in 1995. Joint analysis of parameters searching and bootstrap testing showed that the parameters are getting worse when including EGRET data in 1995. Combination of these results may indicate that a small glitch of Geminga occurred in 1995.
Inverse Correlation of the Ratios of S-Element Abundances in AGB Stars with Metallicity
ZHANG Bo, LIU Jun-hong, LIANG Yan-chun, PENG Qiu-he
Chin. Phys. Lett. 1998, 15 (1): 76-78 .  
Abstract   PDF(pc) (204KB) ( 370 )
In present study, the relations between the ratios of the heavy to light s-element (slow neutron captrue element) abundances and the average neutron exposure are calculated for the intrinsic and extrinsic AGB stars, respectively. In addition, the inverse correlation of these ratios with metallicity is also presented and interpreted quantitatively. This work is based on the evolution of the heavy element abundances of the intrinsic AGB stars, and the calculation on the heavy element overabundances of the extrinsic AGB stars.
31 articles