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Volume 12 Issue 1
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Original Articles
Generating Functional for Truncated Green Functions and an Application to Scattering Matrix
ZHOU Zhining, ZHONG Yushu, LI Xianhui
Chin. Phys. Lett. 1995, 12 (1): 1-3 .  
Abstract   PDF(pc) (119KB) ( 448 )
The generating functional for truncated Green functions which is lacking in the field theories, is introduced for the spinor electrodynamics. Such generating functional is shown to be excellent in expressing the scattering matrix and used to construct a formula for the latter. The method is also applicable in principle to other field theories.

On Beam Study of 198Bi Decay
ZHOU Xiaohong, SUN Xiangfu, LEI Xiangguo, JIN Hanjuan, LIU Zhong, ZHANG Yuhu, PAN Qiangyan, GUO Yingxiang, LUO Yixiao, WEN Shuxian, YUAN Guanjun, LI Guangsheng, YANG Chunxiang
Chin. Phys. Lett. 1995, 12 (1): 4-7 .  
Abstract   PDF(pc) (180KB) ( 385 )
Excited nucleus 198Bi was produced via the 187Re(16O, 5n) 198Bi reaction. The γ-rays following the β+/EC (electron capture) decay of 198Bi were measured in beam by using a powerful multidetector system. Based on coincidences with the known γ-rays of 198Pb, five new transitions were identified and eight new energy levels were established for 198Pb.
On the ls24d Fine Structures of B III and Ne VIII
WANG Zhiwen(Z. W. Wang), Kwong T. Chung, ZHU Xiaowei
Chin. Phys. Lett. 1995, 12 (1): 8-11 .  
Abstract   PDF(pc) (204KB) ( 484 )
The fine structure of lithium-like ls24d states in the literature behaves irregularly as a function of Z. The fine structures of the B III and Ne VIII fall well below the isoelectronic curve. The term energies of these two systems in the data tables also give worse agreement with the theoretical prediction. In this work, we show that the reason for this unusual situation is caused by a misidentification in the original spectra. When the correct identifications are made, the fine structures of both systems fall on the isoelectronic curve and the agreement between theory and experiment is excellent .
Lattice Inversion Method and ab initio Pair Potentials in Cu-Ag, Cu-Au and Ag-Au Intermetallic Compounds
XIE Qian, XU Wei, HUANG Meichun
Chin. Phys. Lett. 1995, 12 (1): 12-15 .  
Abstract   PDF(pc) (174KB) ( 520 )
The lattice inversion method is used to construct ab initio pair potentials in the noble-metal alloy systems Cu-Ag, Cu-Au and Ag-Au from the elemental crystals and a L12 binary superstructure as references. Also, we present an alternative method for the determination of the three-dimensional Möbius functions by using the Kronecker expansion.
Single Electron Capture for Ce+ and Ho+ in H2
WU Weimin, GU Jian, WU Songmao, LU Fuquan, YANG Fujia
Chin. Phys. Lett. 1995, 12 (1): 16-18 .  
Abstract   PDF(pc) (154KB) ( 428 )
The single-electron capture cross sections for the impact of rare-earth ions Ce+, Ho+ on H2 are measured in the energy range 3-8keV by 'growth rate' method. The measurement also reveals that the incident ions are predominantly in ground state.
Hole-Burning in the Excitonic Spectra of Polydiacetylene Under Subresonant Optical Excitation
PENG Jingcui
Chin. Phys. Lett. 1995, 12 (1): 19-22 .  
Abstract   PDF(pc) (160KB) ( 333 )
The hole-burning in the excitonic spectra of polydiacetylene toluene sulfonate under subresonant optical excitation is investigated. Through calculating the nonlinear absorption spectra, the position and depth of the hole are determined based on the phonon-mediated optical Stark effect. The comparison between measured data and theoretical results is made.
Some Remarks on the Steady State Heat Transfer Measurement in the Bath of Subcooled Superfluid Helium
WANG Ruzhu
Chin. Phys. Lett. 1995, 12 (1): 23-26 .  
Abstract   PDF(pc) (223KB) ( 419 )
Peak and recovery heat flux densities (qp, qR) in the bath of subcooled superfluid helium (HeIIp, from 1.81 to 2.1 K at 0.1 MPa). Have been measured, in which a programmed voltage method with a triangle waveform of 20s is applied, and a RhFe wire (d = 51μm, L = 34.8mm) is horizontally immersed in a HeIIp cryostat, which served as sample, heater and temperature sensor.
Flux Growth and Properties of KNPBN Crystal
WANG Shuxin, SONG Yongyuan, CHEN Huanchu, ZHANG Peilin, ZHONG weilie
Chin. Phys. Lett. 1995, 12 (1): 27-29 .  
Abstract   PDF(pc) (140KB) ( 477 )
Potasium sodium lead barium niobate KNPBN crystals have been grown successfully by flux method. The dielectric constant along the polar axis was measured at 50 kHz as a function of temperature in the range of 0 to 400°C. The flux system, diffuse phase transition and optical absorption were also discussed.
Phonon and Electron Densities of States in Amorphous Fe90-xCoxZr10 Alloys
LU Zhichao, XIANYU Ze, LI Jizhou, KANG Jian, YE Chuntang, LI Zhuqi, SHEN Baogen
Chin. Phys. Lett. 1995, 12 (1): 30-33 .  
Abstract   PDF(pc) (201KB) ( 492 )
The generalized phonon density of states (PDOS) and the valence electron density of states (EDOS) of the amorphous Fe90-xCoxZr10 (x=4, 10 and 40) alloys were measured at the room temperature by inelastic neutron-scattering and x-ray photoemission spectroscopy, respectively. Preliminary results show that the stronger the Invar effect, the softer is the PDOS in the low-energy region and the larger is the EDOS at the Fermi energy level. The enhancement of electron-phonon interaction was suggested to explain the low-energy phonon softening observed in Invar alloys.
Photocurrent Studies of β-FeSi2 Thin Films
SHEN Wenzhong, WANG Lianwei, TANG Wenguo, LI Ziyuan, SHEN Xuechu
Chin. Phys. Lett. 1995, 12 (1): 34-37 .  
Abstract   PDF(pc) (178KB) ( 393 )
We report the observation of photocurrent spectrum involving both the fundamental interband, extrinsic defect transitions β-FeSi2 and the intrinsic transitions of Si substrate and demonstrate the sensitivity and reliability of the photocurrent measurement for revealing the energy band structure of β-FeSi2. The transition energies are in good agreement with the results of absorption measurement and the theoretical calculation based on a simple recombination model.
Electron-Hole Interaction in Conjugated Polymers
WU Changqin
Chin. Phys. Lett. 1995, 12 (1): 38-41 .  
Abstract   PDF(pc) (185KB) ( 486 )
The electron-hole interaction in conjugated polymers is considered for both a short chain and an infinite-long polyene. The attraction and repulsion between the electron and hole for different interactions are andysed. Excitonic states should exist in the attractive region.
Flux Pinning in (Bi0.9 Pb0.13)2Sr2(Ca0.98R0.02)2Cu3O10+δ System (R=Sm, Eu, Gd, Dy, Ca)
CAI Dianxian, JIN Xin, SHEN Jiancang, YAO Xixian
Chin. Phys. Lett. 1995, 12 (1): 42-45 .  
Abstract   PDF(pc) (213KB) ( 352 )
The (Bi0.9 Pb0.13)2Sr2(Ca0.98R0.02)2Cu3O10+δ superconductors (R = Sm, Eu, Gd, Dy, Ca) were prepared and the flux pinning effects of all samples were studied using vibrating sample magnetometer. We found that the pinning potential energy U increases but the flux pinning force Fp decreases when the magnetic moment of the rare earth element increases. We believe that this effect may come from the area of normal state resulting from the magnetic moment of the rare earth element which was particularly substituted for the Ca2+ ion of our samples.
Magnetic Properties of Compound Fe-Ta-S
DAI Shouyu, YU Chengtao, JIN Jiucheng, FAN Shiyong
Chin. Phys. Lett. 1995, 12 (1): 46-49 .  
Abstract   PDF(pc) (245KB) ( 410 )
A novel compound Fe-Ta-S crystal has been obtained using iodine vapor transport technology. At low temperature this compound is in a strong diamagnetic state, which is similar to a superconductor. The dependence of the diamagnetic phase transition temperature on the magnetic field could be expressed as Tc = Tc0 + γH2/5 due to a strong coupling between electrons and the magnetic field.

Optical Probing of Free-Carrier Plasma Effects of MeV Ion Implanted Silicon
YU Yuehui, ZOU Shichang, ZHOU Zhuyun, ZHAO Guoqing
Chin. Phys. Lett. 1995, 12 (1): 50-53 .  
Abstract   PDF(pc) (202KB) ( 484 )
Boron ions have been implanted into silicon at an incident energy of 3 MeV to a dose of 5 x 1015 cm-2. Buried conductive layers have been formed in the silicon substrate after annealing at 1050°C for 20s. Infrared (IR) reflection spectrain the wavenumber range of 500-4000cm-1 have been measured and interference fringes related to free-carrier plasma effects observed. By detailed theoretical analysis and computer simulation of the IR reflection spectra, the depth profile of the carrier concentration, the carrier mobility near maximum carrier concentration, and the carrier activation efficiency have been obtained. The physical interpretation of the results was given.
Bright Blue Emission From a New Species of Polymer Diode
ZHANG Zhilin, JIANG Xueyin, XU Shaohong, S. Saito, T. Nagamoto
Chin. Phys. Lett. 1995, 12 (1): 54-57 .  
Abstract   PDF(pc) (162KB) ( 432 )
Blue emitting electroluminescent diode using PVCz doped with perylene and BBOT as electron transport has been constructed. The emission spectrum is a mixture of spectra of BBOT and perylene. A luminance of as high as 680cd/m2 with lumen efficiency more then 0.0281m/W have been obtained.
Cubic Boron Nitride Films Formed by Thermally Assisted rf Plasma CVD
LIAO Kejun, WANG Wanlu
Chin. Phys. Lett. 1995, 12 (1): 58-60 .  
Abstract   PDF(pc) (137KB) ( 504 )
Cubic boron nitride films have been synthesized using thermally assisted rf plasma chemical vapour deposition (CVD) with a tungsten filament in the reactive gasses of B2H6 and NH3. The films obtained are of good quality and are characterized by transmission electron microscope, infrared absorption measurement and electron energy loss spectrometry. Experimental results showed that the structure and quality of cubic boron nitride films closely depend on the growth conditions of the films.
Search for Cosmic Ray Bursts with Energy Above 1014eV
SUN Xinxin, TAN Youheng, YUAN Yukui, DONG Yuju, YUAN Peng, ZHANG Huimin, LI Jing, WANG Hui, HUO Anxiang
Chin. Phys. Lett. 1995, 12 (1): 61-64 .  
Abstract   PDF(pc) (179KB) ( 460 )
The Beijng Huairou extensive air shower (EAS) array has been operating since March 1988. Using data observed during the period from April 1991 through January 1993, a burst of 12 EAS events were observed within 2-minute interval beginning at 4:41’54’’ ante meridiem on December 30 1991 universal time, while only 2 EAS events on average would have been expected during such time interval.

17 articles