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Volume 5 Issue 3
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Original Articles
GeAlAs LASER DIODE PUMPED CESIUM BEAM FREQUENCY STANDARD
WANG Depei, XIE Linzhen, WANG Yiqiu, GUO Shijun*
Chin. Phys. Lett. 1988, 5 (3): 97-100 .  
Abstract   PDF(pc) (52KB) ( 468 )
A laser diode pumped cesium beam frequency standard had been built. The laser diode used for both optical pumping and detection is frequency-locked at the 4-4 transition of Cs D2 line. The Voltage controlled crystal oscillator(VCCO) frequency is locked to the center of the Ramsey pattern of the microwave clock transition after frequency multiplying and synthesizing. The preliminary measurement of the frequency stabilities shows that the results are in agreement with the theory, and better results could be achieved by further improving the frequency stability of the laser diode.
ELECTRON-ELECTRON CORRELATION THROUGH ELECTRON-PLASMON COUPLING IN HIGH-Tc SUPERCONDUCTORS
GUO Weili, ZHANG Pengxiang
Chin. Phys. Lett. 1988, 5 (3): 101-104 .  
Abstract   PDF(pc) (44KB) ( 366 )
A model for high Tc superconductivity is considered. The Cu dx2-y2 electrons correlate by means of polarization-plasmon interaction. We show that when the plasmon energy approaches to the energy difference of the two bands of Cu dx2-y2, a resonant-enhanced interaction between the electrons can be realized. In this model the oxygen vacancies are responsible for the high-Tc superconductivity to which the plasmon frequency is mainly related.

THERMOELECTRIC POWER IN AMORPHOUS Fe84B16 WITH SMALL AMOUNTS OF V, Nb AND Ta ADDITIVES
TONG Litai, LIAO Taichang, HUANG Qi, YAN Shousheng
Chin. Phys. Lett. 1988, 5 (3): 105-108 .  
Abstract   PDF(pc) (50KB) ( 366 )
The thermoelectric power in amorphous (Fe1-xTx)84B16 alloys, where T stands for V, Nb, Ta and x ranges from 0 to 0.08, is measured in the temperature range 77-350K. The results can be qualitatively understood using Mott s-d scattering model or Herzer's theory on the assumption of the occurrence of a virtual bound state near Fermi level. The differences between FeVB, FeNbB and FeTaB systems confirm the existence of a period effect in these alloys.
INVESTIGATING INELASTIC COLLISIONS BY THE DEVIATION CURVE FROM DRUYVESTEYN DISTRIBUTION
YANG Mingjiang, WANG Chaohua
Chin. Phys. Lett. 1988, 5 (3): 109-112 .  
Abstract   PDF(pc) (46KB) ( 436 )
In laser plasma, the real experimental electron energy distribution (EED) f deviates from Druyveteyn distribution fD. This paper suggests that the deviation (f- fD ) of Druyvesteyn distribution, instead of EEDS, can be used to shod clearly some details of excitation and ionization of atoms(molecules), and also gives some examples of CO2, N2, He, Ne and Ar.
RESONANT BEHAVIOUR OF GaAs LO PHONONS IN A GaAs-A1As SUPERLATTICE
ZHANG Shulin, T.A. Gant, M.Delaney, M.V. Klein*, J.Klem, H-Morkoc
Chin. Phys. Lett. 1988, 5 (3): 113-116 .  
Abstract   PDF(pc) (48KB) ( 426 )
Resonant Raman scattering from GaAs LO phonons in a 59Å GaAS/20Å AlAs superlattice was studied. The relevant intersubband energies were determined. The results suggest that all of the exciton transitions from the hole subbands HH1, LH1, HH2, HH3, LH2 and HH4 to the electron subbands CB1 and CB2 in the energy region covered by our incident dye laser were observed and a justificative analysis may involve effects due to valence band mixing and to 3D electronic miniband structure.
X-RAY PHOTOELECTRON SPECTROSCOPY STUDY OF THE SINGLE PHASE HIGH-Tc SUPERCONDUCTOR YBa2Cu3O9-δ
JI Mingrong, HE Zhenghui*, WU Jianxin, CHEN Zhuyao**, QIAN Yitai**, PAN Guoqiang**, ZHANG Qirui*
Chin. Phys. Lett. 1988, 5 (3): 117-120 .  
Abstract   PDF(pc) (48KB) ( 386 )
X-ray Photcelectron Spectroscopy (XPS) was employed to study the single phase high-Tc superconductor YBa2Cu3O9-δ. Comparison. Of the observed valence band spectrum with the theoretical spectrum of Mattheiss is given. The core level spectrum of Ba 3d5/2 was examined. The results of Y2Cu2O5 and Y2BaCuO5 are also reported.


BIFURCATION CURVES OF THE HÉNON MAP DETERMINED BY A MULTIPLE-SHOOTING TECHNIQUE
LING Fuhua ( F.H.Ling)
Chin. Phys. Lett. 1988, 5 (3): 121-124 .  
Abstract   PDF(pc) (46KB) ( 423 )
A multiple shooting method combined with a Newton iteration for determining bifurcation curves of two-dimensional maps is presented. This method is so effective that the high period bifurcation curves which could not be estimated with any other methods can be determined. Some P8 bifurcation curves of the Henon map are calculated as an example.

A STUDY OF ADSORPTION AND DIFFUSION OF HYDROGEN IN THE AUSTBNITIC STAINLESS STEEL BY AP-FIM
REN Dagang
Chin. Phys. Lett. 1988, 5 (3): 125-128 .  
Abstract   PDF(pc) (60KB) ( 419 )
Hydrogen adsorption and diffusion on the surface of austenitic stainless steel are studied with atom probe field ion microscope (AP-FIM). Hydrogen is noticeably adsorbed on the surface at low temperature (85K) and diffuses into the bulk to a depth of about 40 atom layers . The diffusion activation energy is calculated to be 0.22eV ( or 21.2KJ/mol). It is also found that the microstructure of a specimen charged with hydrogen is changed, and the distribution of hydrogen fluctuates with the depth.
EFFECT OF COLD-ROLLING ON THE MAGNETTIC TTRANSITIONS IN Au83Fe17
CHEN Duxing*, J.Nogues, K . V . Rao, C.E.Violet**, R . J.Borg**
Chin. Phys. Lett. 1988, 5 (3): 129-132 .  
Abstract   PDF(pc) (43KB) ( 356 )
The temperature dependences of the dynamic-elastic and viscous susceptibilities have been measured for Au83Fe17, after cold-rolling. It is found that cold-rolling reduces the Curie temperature and raises the spin-freezing temperature remarkably. These results can be explained on the basis of the precipitation medal proposed by Borg and Violet.
MULTIPLICITY DISTRIBUTION IN HIGH ENERGY HADRON COLLISION
LI Chunxian(LEE Chun-shien)
Chin. Phys. Lett. 1988, 5 (3): 133-136 .  
Abstract   PDF(pc) (45KB) ( 357 )
A new independently-produced-many-fireballs model was built up by the author. The relationship between the average number of small fireball k and s1/2 was obtained, the multiplicity distribution was interpreted, and the q-th moment and multiplicity distribution in S1/2 = 2TeV and 40TeV can be predicted by this model.
COMMENTS ON THE ISOTOPE EFFECT IN THE 90K OXIDE SUPERCONDUCTORS
WU Hangsheng, DING Shangwu
Chin. Phys. Lett. 1988, 5 (3): 137-140 .  
Abstract   PDF(pc) (32KB) ( 321 )
In this letter, we point out that the Batlogg et al. experiment does not indicate that in the oxide superconductors Ba2YCu3O7 and Ba2EuCu3O7, the isotope effect, if existed. would be very small, but instead, shows that the coupling between electron and the high frequency lattice vibration involving oxygen is weak.
EIGENVALUES OF ENERGY LEVELS AND NONLINEAR INTERACTIONS FOR MULTIPARTICLE SYSTEM
WANG Zhengzhi
Chin. Phys. Lett. 1988, 5 (3): 141-144 .  
Abstract   PDF(pc) (40KB) ( 358 )
The energy levels, En. of pions in multiparticle systems have been calculated by using the probability distribution, P(n,k), of the independent-creation model of multi-fire balls and the density matrix method of quantum statistics. The result, En = E0 +nkBTln( 1+1/n )-kBTln x Γ(n+k) /Γ(k) Γ(n+1), shows that the nonlinear interaction depends on k. and it can take place only between different fire-balls.
12 articles