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Volume 12 Issue 4
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Original Articles
Berry Phase of Spinor Fields Induced by Gravity and Inertia
WU Youlin, MENG Guangda
Chin. Phys. Lett. 1995, 12 (4): 193-196 .  
Abstract   PDF(pc) (6099KB) ( 916 )
The Berry phase of spinor fields induced by gravity and inertia are studied starting with covariant Dirac equation in general relativity. The results obtained reveal the spin-gravity coupling effect explicitly. As examples the phase shifts induced by inertial fields of rotating frame and by Earth’s fields are evaluated and some comments on the evaluation are discussed.
Predidtion of the Multiplicity Distributions at Tevatron/LHC Energies and the Approach to Asymptotic KNO Scaling
LIU Hongping, WU Yuanfang, LIU Lianshou
Chin. Phys. Lett. 1995, 12 (4): 197-199 .  
Abstract   PDF(pc) (146KB) ( 561 )
The multiplicity distributions at Tevatron/large hadron collider (LHC) energies are predicted. The approximate Koba, Neilsen, Olesen (KNO) scaling at lower energies and its violation at above intersectin6 storage ring energy are discussed by using three fire ball model. It is predicted that there will appear a new KNO scaling in multiplicity distributions at asymptotic energy region after LHC.
Energy Dependence of the 12C+12C Scattering Described by an Energy Independent Real Part Potential
LI Qingrun, YANG Yongxu
Chin. Phys. Lett. 1995, 12 (4): 200-202 .  
Abstract   PDF(pc) (153KB) ( 471 )
An energy independent real part potential is presented. This potential can well describe the energy dependent experimental data for the 12C+12C scattering in the energy region of Ec.m.≈ 30-80 MeV.


Squeezed Vibrational States in a Quantized Trap
ZENG Heping, LIN Fucheng
Chin. Phys. Lett. 1995, 12 (4): 203-206 .  
Abstract   PDF(pc) (184KB) ( 491 )
The quantized center of mass (c. m.) motion of a single two-level atom or ion confined in a one-dimensional harmonic potential and interacting with a single-mode classical traveling laser field, is investigated. We show that both quadrature and amplitude squared squeezed vibrational states can be generated in this simple trap model when c. m. motion is initially in a certain coherent trap state.
Temperature of Transformation from Fullerite to Amorphous Carbon
CHENG Guangxu( Guang-Xu Cheng), GU Gang, ZANG Wencheng, DU Youwei, FENG Duan
Chin. Phys. Lett. 1995, 12 (4): 207-209 .  
Abstract   PDF(pc) (118KB) ( 553 )
Raman spectra during the transformation from fullerite to amorphous carbon are analyzed. The transformation temperature is obtained from intensity ratio of Stokes and anti-Stokes lines by using Placzek’s formula. The temperature, less than 2.0 x103K, is in consistence with previous work.
Observation of Optical Bistabilities in a Doped Polymer Thin Film Quasi-waveguide
WANG Huitian, DONG Fengzhong, ZHANG Zhanxiang, YE Peixian QIU Ling, SHEN Jifeng, FU Xingfa, SHEN Yuquan
Chin. Phys. Lett. 1995, 12 (4): 210-212 .  
Abstract   PDF(pc) (161KB) ( 451 )
Optical bistability was observed and studied in the output of reflected beam as well as in that of m-lines in a doped polymer thin film quasi-waveguide. The physical origin was demonstrated to be the existence of a mode spectrum and the high third order nonlinearity of the polymer film. It was also observed for the first time that the intensity variation of the reflected beam and the m-line in the hysteresis loops are complementary to each other.
All-Fiber Ring Resonator Gyroscope
YAO Yi, SHI Kun, LU Weidong, JIAN Shuisheng
Chin. Phys. Lett. 1995, 12 (4): 213-216 .  
Abstract   PDF(pc) (247KB) ( 541 )
An all-fiber resonator optic gyroscope employing a spliceless polarization maintaining fiber resonator with 90°polarization rotation in the lapped coupler is presented. A frequency-modulation spectroscopy technique using two piezoelectric transducer phase modulators has been theoretically analyzed and experiment ally demonstrated for rotation sensing. The short term bias stability better than 16°/h with integration time of 10s has been obtained. The main error sources of optical system are discussed and some reduction measures are suggested.
Investigation of C60 Single Crystal by X-Ray Methods
LI Chaorong, MAI Zhenhong, WANG Gang, WANG Yutian, WU Lansheng, CUI Shufan, XIE Sishen, JIANG Jianhua
Chin. Phys. Lett. 1995, 12 (4): 217-220 .  
Abstract   PDF(pc) (221KB) ( 490 )
C60 single crystals grown by a single-temperature-gradient technique were characterized by synchrotron radiation white beam x-ray topography and x-ray double crystal diffraction with Cu Kα1 radiation on conventional x-ray source. The results show that the crystal is rather well crystallized. The x-ray topographies give an evidence of dendritic growth mechanism of C60 single crystal, and x-ray double crystal diffraction rocking curve shows that there are mosaic structural defects in the sample. A phase transition at 249 ± 1.5K from a simple cubic to a face centered cubic structure is confirmed by in situ observation of synchrotron radiation white beam x-ray topography with the temperature varing from 230 to 295K.
Inverse Lattice Problem and Finnis-Sinclair Model
XIE Qian*, HUANG Meichun
Chin. Phys. Lett. 1995, 12 (4): 221-224 .  
Abstract   PDF(pc) (171KB) ( 361 )
The lattice inversion method is used to construct the pair potential and the hopping integral in Finnis-Sinclair model. In the approach, the lattice sum of square hopping integral is assumed to be an exponential function versus the nearest-neighbour distance, with two parameters determined from the Cauchy discrepancy and the difference of the unrelaxed vacancy-formation energy with the sublimation energy. The individual hopping integral is inverted from the exponential function and the pair potential is inverted from the remaining part of total cohesive energy.
Abnormal Viscosity of A1 Electro-Rheology Fluid
YI Sunsheng, SUN Jirong, WANG Chaoying, LU Kunquan, YI Heling*
Chin. Phys. Lett. 1995, 12 (4): 225-228 .  
Abstract   PDF(pc) (278KB) ( 444 )
The viscosity of the mixture of metal particles Al and silica oil is studied under different ac electric field at room temperature. The viscosity increases with rising field until a maximum (about two times of that at zero field) at about 2.5MV/m and a tendency of decrease appears after this critical field. Microscope observation shows that this special behavior corresponds to the formation and destruction of fiber structure in A1 electro-rheology fluids.
Sensitive Single-Level Magnetometers of High Tc dc SQUIDS
WANG Shiguang, DAI Yuandong, ZENG Xianghui, ZHENG Peihui, WANG Shouzheng, XIONG Guangcheng, LIAN Guijun, GAN Zizhao
Chin. Phys. Lett. 1995, 12 (4): 229-232 .  
Abstract   PDF(pc) (258KB) ( 464 )
We have developed a simple sintering system to prepare the yttria-stabilized-zirconia (YSZ) bicrystals. Grain-boundary junctions made from the epitaxial YBa2Cu3O7-δ films on the bicrystal substrates demonstrated Josephson behavior. Using new square washer design, single-level magnetometer of dc superconducting quantum interference. device (SQUID) has been fabricated. Owing to the flux focusing effect of the large washer, the magnetic field sensitivity of the devices has been enhanced. The magnetic field resolution of the magnetometer is IpT/Hz1/2 at 10Hz, and increases to 3pT/Hz1/2 at 1Hz at 77K.

Flux Creep Determination of Field Dependence of Magnetic Jc at Low Temperatures
RUI Ying, JI Helin, XU Xiaonong, QIN Mengjun, SHAO Huimin, JIN Xin, YAO Xixian
Chin. Phys. Lett. 1995, 12 (4): 233-236 .  
Abstract   PDF(pc) (213KB) ( 455 )
The effective activation energy of one HgBaCaCuO 1223 superconductor as a function of current density was extracted from the magnetic relaxation measurements below 30K, and found to obey a power law. We also obtained effective activation energy as a function of current density from the magnetic hysteresis loops (M-H). The data sets for the M-H loops at different temperatures overlap each other, and all fall on the smooth Ueff( J,0 ) curve based solely on the magnetization relaxation measurements. This indicates that the field dependence of magnetic critical current density is determined by the flux creep via nonlinear effective activation energy at low temperatures.
A RKKY Model Fitting of Nuclear Magnetic Resonance Spectra of 63Cu in Fe/Cu Multilayers
ZHAI Ya, ZHU Xiaobing, HU Chen, ZHU Jiangang, LU Mu, ZHAI Hongru
Chin. Phys. Lett. 1995, 12 (4): 237-240 .  
Abstract   PDF(pc) (203KB) ( 417 )
In this letter, a theoretical fit of nuclear magnetic resonance spectra of 63Cu in Cu layers of Fe/Cu multilayers is given based on RKKY theory. The values of exchange field and additional Knight shift are fitted, which agree approximately with the experimental data.
High-pressure Mössbauer Study of Metastable 304 Stainless Steel with bcc Structure
LI Fashen, SUN Jijun, C. L. Chien*
Chin. Phys. Lett. 1995, 12 (4): 241-244 .  
Abstract   PDF(pc) (200KB) ( 682 )
The ferromagnetic metastable bcc 304 stainless steel film was studied by means of 57Fe high-pressure Mössbauer spectroscopy. No fcc phase was observed under the pressure up to 36 kbar. However, the magnetization direction of the sample was found to reorientate under the high-pressure, and showed the strongest tendency to the out-of-plane under the pressure 8 kbar, then was gradually close to the in-plane with increasing pressure.
Enhanced Near-Edge Transitions by Unsaturated Si Atoms in Porous Silicon
FU Huaxiang, XIE Xide
Chin. Phys. Lett. 1995, 12 (4): 245-248 .  
Abstract   PDF(pc) (246KB) ( 465 )
The photo-induced transition probability for porous silicon under different surface conditions is studied. The enhanced near-edge transitions for the presence of unsaturated Si atoms at the surface of porous silicon are found. The theoretical results are in good agreement with those obtained in several recent experiments. Based on the calculated results, an effective way to improve the photoluminescence efficiency in porous silicon is provided, and a model about the origin of luminescence in porous silicon is suggested.
Pulsed Laser Deposition of Optical Waveguiding LiNbO3 Films on SiO2 Substrate
GUO Xinli, LIU Junming, LIU Zhiguo, ZHU Shining
Chin. Phys. Lett. 1995, 12 (4): 249-252 .  
Abstract   PDF(pc) (256KB) ( 405 )
The optical waveguiding lithium niobate (LiNbO3) films have been prepared on (001)-oriented SiO2 substrates by pulsed lager deposition technique. The x-ray diffraction and scanning electron microscopy were used to characterize the as-grown films, and revealed that highly (012)-textured LiNbO3 films with smooth surface were achieved. The optical waveguiding properties of these films were demonstrated by m-line measurements of transverse-magnetic and transverse-electric multimodes.
Phase-Locking of a Gunn Oscillator at 3mm Waveband Using High Temperature Superconducting Josephson Junction Harmonic Mixer
WANG Huabing, XU Weiwei, CHENG Qiheng, JI Zhengming, GAO Ruizhang, WU Peiheng, XU Zhicai*
Chin. Phys. Lett. 1995, 12 (4): 253-256 .  
Abstract   PDF(pc) (219KB) ( 1213 )
A Gunn oscillator at 3mm waveband has been phase-locked to a synthesizer local oscillator using a high Tc YBa2C3O7-δ Josephson junction operated at 77K as the harmonic mixer, with harmonic numbers up to 52. The observed spectrum of the phase-locked output at the intermediate frequency (IF) shows clearly that the quality of the phase-locking is very good. To drive the analogue phase locking loop successfully, it is essential to have IF output and signal-to-noise ratio both as high as possible.
17 articles