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Volume 5 Issue 6
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Original Articles
A PULSE COLOR-CENTER LASER USING F+3 CENTER IN LiF CRYSTAL AT ROOM TEMPERATURE
GU Hongen, GUO Shaozhang, RUAN Yongfeng, WAN Liangfeng
Chin. Phys. Lett. 1988, 5 (6): 241-242 .  
Abstract   PDF(pc) (25KB) ( 402 )
A pulsed LiF:F+3 centers laser coaxially pumped by a nitrogenlaser- pumped dye laser operhting at 460nm is reported. The laser output extended from 510nm to 580nm using an LiF crystal and a single pump wavelength. Eight hundred watts peak power with a pulse duration of 4ns is obtained at room temperature.
IS THE LORENTZ SYMMETRY EXACT?
A . Tartaglia, ZHANG Yuanzhong
Chin. Phys. Lett. 1988, 5 (6): 243-244 .  
Abstract   PDF(pc) (24KB) ( 322 )
A theory that allows for the break of the Lorentz symmetry in the tangent space-time within a Riemannian geometric framework was studied. The conclusion is that the Riemannian geometry is not compatible with the absence of an exact Lorentz symmetry in the tangent space-time. If one wants to explore the consequences of Lorentz symmetry breaking in four dimensions other ways must be tried and/or a higher number of dimensions must be considered.
DIPOLAR SPLITTING IN 7Li NMR SPECTRUM OF α-LiIO3 SINGLE CRYSTAL
MENG Qingan, YANG Jichun
Chin. Phys. Lett. 1988, 5 (6): 245-248 .  
Abstract   PDF(pc) (45KB) ( 401 )
7Li NMR spectrum shows surprisingly both the dipolar and quadrupolar splittings. An approach to calculate the spectrum was suggested by considering only the nearest homonuclear dipolar interaction. The simulating result is consistent with that of the experiment.
JOSEPHSON EFFECTS IN Nb/YBa2Cu307-δ POINT CONTACTS AND YBa2Cu307-δ BREAK JUNCTIONS
ZHAO Shiping, TAO Hongjie, CHEN Yingfei, YANG Qiansheng, LIAO Qide*, A Shao*, XU Xiaozhen*
Chin. Phys. Lett. 1988, 5 (6): 249-252 .  
Abstract   PDF(pc) (54KB) ( 369 )
Josephson effects have been observed in Nb/YBa2Cu307-δ point
contacts and YBa2Cu307-δ break junctions. When the junctions are exposed to a microwave field, the I -V characteristics show constant voltage steps, the heights of which follow the Bessel function behavior. Obvious asymmetry about zero bias has been observed in YBCO break junctions which, we suggest, may possibly result from flux trapping in the complicated weak link structure of the system. Micrmave-induced sub-steps have also been found in YBCO break junctions. All experiments were conducted at liquid helium temperature.

THE ROLE OF SURFACE SHELL OF THE YBa2Cu3Ox SINGLE CRYSTAL IN HIGH Tc SUPERCONDUCTIVITY
DUAN Hongmin, LU Li, ZHANG Dianlin
Chin. Phys. Lett. 1988, 5 (6): 253-256 .  
Abstract   PDF(pc) (43KB) ( 374 )
We have measured the susceptibilities of the YBa2Cu3Ox single crystals, which were obtained by crushing the original ones to different sized. The susceptibility decreases rapidly as the size reduces. It indicates that the superconductivity exists only in the shell of a single crystal.
A SU(7)x SU(7) PREON MODEL
YU Fu, LIU Jueping
Chin. Phys. Lett. 1988, 5 (6): 257-260 .  
Abstract   PDF(pc) (42KB) ( 362 )
We propose a SU(7)x SU(7) preon model which obeys both the 'tHooft anomaly-matching and decoupling conditions, and contains four generations of leptons and quarks. The mass spectrum of particles is obtained to be consistent with experiments via three dynamical symmetry breaking steps.
NONLINEAR SCATTERING AND ATTENUATION OF FIRST SOUND IN SUPERFLUID 4He AT HIGH FREQUENCY AND TEMPERATURE NEAR Tλ
CHENG Jianchun, WEI Rongjue
Chin. Phys. Lett. 1988, 5 (6): 261-264 .  
Abstract   PDF(pc) (41KB) ( 360 )
The attenuation coefficient of the impressed first sound due to the scattering of random background of the second sound is calculated. The result shows that this is an important factor which gives rise the attenuation of the first sound in the vicinity of transition temperature Tλ at very high frequencies of GHz range. The predicted value agrees with the measured data in order of magnitude.
SURFACE SELF-DIFFUSION AND THERMAL ROUGHENING OF TUNGSTEN SURFACES STUDIED BY FIELD EMISSION FLUCTUATION METHOD
GONG Yunming, R.Gomer*
Chin. Phys. Lett. 1988, 5 (6): 265-268 .  
Abstract   PDF(pc) (50KB) ( 370 )
Surface self-diffusion measurements of tungsten atoms and other defects were carried out by means of field emission fluctuation method at various positions along the zones (011)-(112) and (011) -(001).The experimental results shod that the self-diffusion on stepped surface can be used to investigate thermal roughening procedures.
A NEW INTERIOR REISSNER-NORDSTRöM SOLUTION
WANG Xingxiang
Chin. Phys. Lett. 1988, 5 (6): 269-272 .  
Abstract   PDF(pc) (35KB) ( 404 )
A new interior Reissner-Nordström solution is presented. The Solution includes the Florides solution as a special case and can reduce to the Wyman's interior solution in the limit of vanishing charge.
INTERNAL FRICTION STUDY ON STRUCTURAL RELAXATION OF METALLIC GLASSES
LI Xiaoguang, HE Yizhen
Chin. Phys. Lett. 1988, 5 (6): 273-276 .  
Abstract   PDF(pc) (44KB) ( 499 )
During structural relaxation of a glassy matrix, the apparent internal friction (Q-1) decreased with the increase of annealing time (t). The dependence of Q-1 on t can be shown as Q-1=At+B, where A, B and β are constants.
DETERMINATION OF PRESSURE BROADENING COEFEICIENTS OF NO2 BY LASER MAGNETIC RESONANCE*
CHEN Yangqin, LIU Yuyan, LI Fengyan, LI Jinrui and HE Kuanglin
Chin. Phys. Lett. 1988, 5 (6): 277-280 .  
Abstract   PDF(pc) (50KB) ( 566 )
A method which is an indirect measurement of spectral line width using the technique of laser magnetic resonance is described in this letter. The pressure broadening parameters γ° NO2- NO2, He,N2,O2, air were deter- mined to be 5.3±0.5,1.l±0.2,2.7±0.1,1.9±0.2,2.5±0.1MHz/Torr respectively at room temperature.


THEORETICAL DETERMINATION OF TWIN BOUNDARIES IN R-PHASE OF Ni-Ti SHAPE MEMORY ALLOYS
H.C.Yi, M.Zhu and D.Z.Yang
Chin. Phys. Lett. 1988, 5 (6): 281-284 .  
Abstract   PDF(pc) (39KB) ( 409 )
Twin boundaries among different variants in Nitinal R-phase were determined using group decomposition theory. It was found that there are four variants in the R-phase. The four variants may form three types of self-accommodation group. The four variants are twin related with {l00}p and {l00}p as twin planes. These results are in good agreement with the experiment data.
COMMENT ON BLOCHS THEOREM ON THEORIES OF SUPERCONDUCTIVITY
CHENG Kaijia
Chin. Phys. Lett. 1988, 5 (6): 285-288 .  
Abstract   PDF(pc) (40KB) ( 401 )

13 articles