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Vol. 34, No. 1 (1985)

1985-01-05
CONTENT
A SEARCH FOR π-N INTERACTION BY QUARK MODEL
YANG JIAN-HUA, YANG RONG-FU, HE QI-ZHI, CHENG GUO-JUN
1985, 34 (1): 1-9. doi: 10.7498/aps.34.1
Abstract +
By means of quark potential model and Warke approximation, and introducing as compensation intermediate potential (-1)T+JKre(-r/a2) in the phenomenological one gluon exchange quark interaction potential, the pion-nucleon interaction potential is calculated. The phase shifts of p-N scattering in the six channels S11, S31, P11, P31, P13, P33 are determined for the incident pion kinetic energy in the laboratory coordinate system up to 700 MeV. These results are compared with the experimentally determined phase shifts.
ON THE LINE BROADENING AND SHIFTS OF Al-LASER PRODUCED PLASMA
SHE YONG-BO, CHEN YUN-FANG, ZHAO RU-WEN, ZHANG XIU-LAN, PAN GUANG-YAN
1985, 34 (1): 10-16. doi: 10.7498/aps.34.10
Abstract +
We have studied the spatially resolved spectra of Allaser produced plasma. In the range from 2300-4000 ? about thirty emission lines have been observed belonging to the neutral, singly and doubly ionized Al species. Their line widths and shifts vary with the distance between the plasma and the Al-target surface. Five lines from differently ionized species have been examined with the aid of the theoretical formula given by Griem, and the distribution of electron density near the target has been determined semi-empirically. We found that the line broadening of the different species coincided well with each other, and could be used as a measure of electron density in the range from 1·1017 to 5·1018cm-3. But the coincidence between the line shifts seems not so good, especially for the lines of 3587 ? of Al II and 3610 ? of Al III. It remains to be further investigated.
THE EFFECT OF AN INJECTION SIGNAL ON THE FREE-ELECTRON-LASER
G. T. MOORE, M. O. SCULLY, FANG HONG-LIE
1985, 34 (1): 17-23. doi: 10.7498/aps.34.17
Abstract +
In this paper, the effects of an injection signal on the Free-Electron-Laser are investigated. And the reason of and the method for suppressing the break-up of the optical pulses in a Free-Electron-Laser are found.
THRESHOLD AND ENERGY TRANSFER EFFICIENCY IN HIGH PRESSURE HYDROGEN SRS
ZHOU SHOU-HUAN, GUO YI-LI, DING HAI-SHU, YAO MIN-YAN, LOU CAI-YUN, LI GANG
1985, 34 (1): 24-31. doi: 10.7498/aps.34.24
Abstract +
In this work, the influences of several parameters (molecular density of medium, transition linewidth, photon density of pump laser and nonlinear interaction length) on high pressure H2 stimulated Raman scattering (SRS) threshold and energy transfer efficiency are investigated. The experiments were carried out on a Q(1) line vibration transition (4155 cm-1) SRS. Results of effect of H2 pressure (0 to 24 atm) on the threshold are coincident with the analysis of the combined effect of Dicke-Doppler and collision broadening. The influences of stimulated Raman process (SRP) and four-wave parametric processes (FWPP) on energy transfer efficiency, as well as the role of pressure-dispersion effect on higher order anti-Stokes are also discussed.
THE LINE SHAPE ANALYSIS FOR Si L2,3 VV AUGER SPECTRA OF CLEAVED Si (111) SURFACES WITH OXYGEN ADSORBED
XU ZHI-ZHONG, DAI DAO-XUAN, ZOU HUI-LIANG
1985, 34 (1): 32-38. doi: 10.7498/aps.34.32
Abstract +
By digital integration, background subtraction and self-deconvolution for SiL2,3VV Auger spectra measured on the cleaved clean Si (111) surface and that with oxygen adsorbed, the partial transition densities of state of clean surface and adsorbed surface are obtained. With reference to other experimental and theoretical results, it could be inferred from these partail transition densities of state that oxygen is adsorbed both in a molecular state and in an atomic state, and in the adsorbed stage the oxide may also be formed.
MAGNETIC STRUCTURE AND MAGNETIC PROPERTIES OF Y3Fe5-xMnxO12
YU MEI, LIU JIN, LIU ZUN-XIAO, YANG JI-LIAN, JIN LAN, ZHANG BAI-SHENG, ZHOU HUI-MING
1985, 34 (1): 39-47. doi: 10.7498/aps.34.39
Abstract +
Neutron diffraction patterns have been obtained for polycrystalline Y3Fe5-xMnxO12 at 300 K. The fraction of octahedral sites occupied by Mn3+ has been found to be 0.72 for x=0.05 and 1 for x=0.09. The magnetic moments of tetrahedral sites and octahedral sites have been determined respectively for x=0.05 and 0.09. The observed magnetic scattering is consistent with the Neel model and the measured saturation moment.Magnetizations were measured as a function of applied magnetic field from 800 Oe to 10 kOe in the range of 1.5-300 K. Magnetic anisotropy were determined from the approach to saturation, |k1| was found to decrease with Mn3+ content.
CRYSTALLIZATION OF AMORPHOUS Ni83Cr7Fe3Si4B3 ALLOY UNDER ATMOSPHERE AND HIGH PRESSURE
WANG ZHAO, MENG ZHAO-FU, WANG YU-MING, WANG WEN-KUI, WANG SONG-TAO
1985, 34 (1): 48-55. doi: 10.7498/aps.34.48
Abstract +
In this paper, the crystallization of the amorphous Ni83Cr7Fe3Si4B3 alloy was investigated and its "T-T-T" diagrams under 1 bar and 100 kbar were obtained. The results indicate that the crystallization temperature decreases and the metastable II phase does not form if the amorphous state is subjected to high pressure annealing. In addition, the activation energy of crystallization under 1 bar and 100 kbar was calculated respectively.
FAR-INFRARED REFLECTION SPECTRA AND THE MULTIMODE MODEL FOR MIXED CRYSTAL CdxHg1-xTe
SHEN XUE-CHU, CHU JUN-HAO
1985, 34 (1): 56-64. doi: 10.7498/aps.34.56
Abstract +
Far-infrared reflection spectra in the wavenumber region between 15 to 500 cm-1 are obtained and studied for the mixed crystals CdxHg1-xTe with different compositions from 0.18 to 0.45 at the temperatures between 4.2 to 300 K. In addition to the fine structures of the CdTe-like optical phonon reflection band, the complex structure of the HgTe-like band for the low composition sample has been observed, and the dependences of the spectral structures on the composition and the temperature of the samples have also been investigated. The fine structures of the reflection spectra are explained based on the multimode quasi-harmonic oscillator model.By means of the classical oscillator matching method, the curve-fitting calculations are performed for the experimental reflection spectra, and the dielectric function spectra and other optical constants versus frequencies are obtained from a satisfactory fitting.
ON THE SINGULAR PERTURBATION SOLUTION OF BOLTZMANN EQUATION (Ⅰ)
DING E-JIANG, HUANG ZU-QIA
1985, 34 (1): 65-76. doi: 10.7498/aps.34.65
Abstract +
In this paper, we use a kind of singular perturbation method to find the normal solution of the Boltzmann equation with small Knudsen number. It is proved that the secular terms may be removed by improving the Hilbert expansion and Enskog expansion.
ON THE SINGULAR PERTURBATION SOLUTION OF BOLTZMANN EQUATION (Ⅱ) "INITIAL LAYER" SOLUTION
DING E-JIANG, HUANG ZU-QIA
1985, 34 (1): 77-87. doi: 10.7498/aps.34.77
Abstract +
In solving Boltzmann equation with a small Knudson number, we improved Grad expansion and got an "initial layer" solution without secular terms. This solution indicates that high-moment sound waves may exist in gases.
TEMPORAL AND SPATIAL DISTRIBUTION OF DIRECTOR ANGLES IN SOLITON EXPERIMENTS OF LIQUID CRYSTALS
SHU CHANG-QING, XU GANG, LIN LEI
1985, 34 (1): 88-96. doi: 10.7498/aps.34.88
Abstract +
It is pointed out that more than one temporal and spatial distribution of director angles can be obtained from the interference patterns (varying in space and time) of transmitted polarized (monochromatic and white) light from liquid crystals. When specific physical conditions (e.g. the time variation of the local velocities of nonlinear waves described by shearing director equation of soltons) are taken into account, the above uncertainty can be removed. Detailed discussions on the case of solitons in shearing nematics are given. Numerical calculations show that the spatial distribution of director angles given in Eef. [5] is in contradiction to the directions of velocities of the three dark lines (under white light) observed experimentally if the one-dimensional shearing director equation of solitons is assumed. A distribution of director angles in better agreement with experiments is given.
THE PROXIMITY EFFECT BETWEEN A NONSIMPLE METAL WITH-U CENTERS AND A BCS SUPERCONDUCTOR (Ⅱ)
TANG HUI, ZHANG LI-YUAN
1985, 34 (1): 97-104. doi: 10.7498/aps.34.97
Abstract +
According to the model of the superconducting proximity effect between a nonsimple metal thin film with negative U centers and a thin film of BCS superconductor, we have discussed the gap functions, the electronic density of states and the transition temperature Tc varying with different parameters. Results show that a small density of states due to the -U centers exists in the region of "energy gap". The transition temperature of this kind of sandwich is probably higher than the Tc of the bulk BCS superconductor within certain range of parameters.
BRIEF REPORT
THE EXACT SOLUTION OF RELAXATION PROCESS OF AN OSCILLATOR IN A THERMO-BATH
A. GRECOS, HU GANG
1985, 34 (1): 105-111. doi: 10.7498/aps.34.105
Abstract +
Starting from the Von Neumanm equation, the exact solution of the transition probability of an oscillator coupled with a thermo-bath is obtained, without the weak coupling approximation. The equilibrium distribution for the oscillator is given expli-citely as well.
XPS STUDY OF THE OXIDES ON THE SURFACE OF NbN THIN FILM
WANG XIE-WEN, WU SI-CHENG
1985, 34 (1): 112-116. doi: 10.7498/aps.34.112
Abstract +
The composition of the oxides formed at room temperature in the atmosphere or by rf oxidation on the surfaces of NbN thin films were characterized by means of X-ray photoelectron spectroscopy. The experimental Nb3d spectra show that the interfacial phase formed between NbN substrate and the niobium pentoxide is different from the case of pure niobium. It is Nb2O3 but not a mixture of NbO and NbO2. The surface of NbN seems to have the ability of protecting itself from the formation of conducting suboxides such as Nb2O, NbO etc. This is useful for improving the quality of the superconducting tunnel junction with oxide barrier.
INVERSION OF p-TYPE SILICON TO n-TYPE BY PULSED LASER IRRADIATION
WANG HONG-KAI, YAO JIE, CHEN BAO-QIONG
1985, 34 (1): 117-120. doi: 10.7498/aps.34.117
Abstract +
This paper describes an effect of the inversion of silicon single crystal from p-type to n-type by the irradiation of ruby pulsed laser. This effect is a function of the impurity compensation but independent of the oxygen content, the crystal cut and the crystal-growing process. Experimental results show that p-type silicon crystals with phosphorus impurity compensation higher than 7% are susceptible to inversion by pulsed laser irradiation when the amount of impurity compensation increases and the distribution of impurity compensation changes. The concentration profile of phosphorus atoms is given by SIMA technique.
INVESTIGATION ON SPIN PINNING EFFECT OF THE MAGNETITE PARTICLE SURFACE COATED WITH ORGANISM
LU HUAI-XIAN, DU YOU-WEI, WANG TING-XIANG, ZHANG YU-CHANG
1985, 34 (1): 121-125. doi: 10.7498/aps.34.121
Abstract +
The M?ssbauer spectra of 80 ? magnetite particles before and after coating with the three different organic surfactants were measured. The M?ssbauer spectra after coating appear as dispersion to a different degree with the different organism. When magnetic field (8 kOe) was applied, the superparamagnetic spectra for all sample disappeared and the spectra appeared as sextets. The experimental results showed that the organism produce pinning of the spin of the iron ions on the magnetite particle surface. The depth of pinning with and without applied magnetic field were calculated.
MAGNETO-OPTICAL FARADAY ROTATION IN Bi4Ge3O12 CRYSTAL
WANG HUAN-YUAN, JIA WEI-YI, SHEN JING-XING
1985, 34 (1): 126-128. doi: 10.7498/aps.34.126
Abstract +
The dispersion relation of magneto-optic Faraday rotation in crystal Bi4Ge3O12 was measured in the visible region. The variation of Faraday rotation with temperature was also measured at 633 nm between room temperature and liquid nitrogen temperature. Large Faraday rotation together with high transparency in wide wave length region makes it a valuable magneto-optic material as well. The important role of Bi ions in diamagnetic crystal in magneto-optic rotation was briefly discussed.
INVESTIGATION OF M-, W-, X-TYPE HEXAGONAL BARIUM FERRITES M?SSBAUER SPECTRA
LIU PENG-XIA, LU HUAI-XIAN, DU YOU-WEI, WANG TING-XIANG, JIAO HONG-ZHEN, ZHANG YU-CHANG
1985, 34 (1): 129-133. doi: 10.7498/aps.34.129
Abstract +
The M?ssbauer spectra for the M-, W- and X-type hexagonal barium ferrites were measured. We obtained the M?ssbauer spectra parameters of the M- and W-type ferrites, using the method of trial and error of a number of superposed six-line Lorentzian spectra with experimental spectra. In crystallographic consideration the X-type ferrites may by regarded as a superposition of M- and W-type. Then we obtained eleven six-line sub-spectra of the X-type with good fitting of experimental data.
ULTRASONIC ATTENUATION IN STEEL DURING FATIGUE
PAN ZHENG-LIANG, WANG SHUANG-QUAN, LI GUANG-YI
1985, 34 (1): 134-139. doi: 10.7498/aps.34.134
Abstract +
The fatigue crack length a and the changes of ultrasonic attenuation △α at frequency 10 MHz 011 compact test sample of 30CrMnSiNi2A steel have been simutane-uosly measured as a function of fatigue cycle number N. It was shown that the △α(N) curve was in good response to the a(N) curve and the △α was traced out during the period of crack nucleation. The ultrasonic attenuation a as a function of load P in pulsating tension fatigue test has been investigated. When Pc, where Pc is a critical load, a decreases wth increase of the load; when P>Pc, a increases rapidly with increase of the load. A depinning model of dislocations is suggested. The ultrasonic attenuation is a very useful tool for studying the growth of fatigue crack.
ELECTRICAL PROPERTIES OF A NEW PYROELECTRIC BARIUM METABORATE CRYSTAL IN LOW TEMPERA-TURE PHASES AND ITS POTENTIAL APPLICA-TION IN INFRARED PYROELECTRIC DETECTOR
SHI ZI-KANG, JIANG AI-DONG, YE HAI-TAO, CHEN CHUANG-TIAN
1985, 34 (1): 140-144. doi: 10.7498/aps.34.140
Abstract +
We investigated systimatically the electrical properties of the barium metaborate crystal in low temperature phases and found a new type of pyroelectric crystal materials, the single crystal samples of which grew in our laboratory. According to experimental investigations on many of its physical propenties, such as the dicalectric constant, de-resistivity, loss angle, pyroelectric coefficient, Cp, as well as transparency, it may be expected that this material would be useful for application in high power infrared pyroelectric detectors.