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Vol. 40, No. 11 (1991)

1991-06-05
GENERAL
SOLUTIONS TO THE q-DEFORMED OSCILLATOR SYSTEM AND THE Hq(4) SYMMETRY
YAN HONG
1991, 40 (11): 1729-1735. doi: 10.7498/aps.40.1729
Abstract +
A discussion on the q-oscillator system and the algebra Hq(4) is presented, emphasizing the case of |q| = 1 in particular. A remarkable connection between algebras SUq(2) and Hq(4) is given. The single q-oscillator system is solved and shown to be analogous to the parafermion-(PF), with the specific cases analogous to 2nd and 3rd order PF's discussed in detail. The properties of the representations of Hq(4) and a finite chain model of q-oscillators are discussed-
MEAN FREE PATH OF PARTICLES IN FHP HYDRODYNAMICAL MODELS
LIU MU-REN, KONG LING-JIANG, JIANG FENG
1991, 40 (11): 1736-1740. doi: 10.7498/aps.40.1736
Abstract +
The mean free path of the FHP hydrodynamical models is calculated. The calculations show that the mean free path is approximate to a constant after more than 60 collisions and is a minimum, which is corresponding to the maximum of Reynolds' number, when particle density is 0.25. In addition, the difference between the FHP models and the molecular dynamic models is showed clearly.
NUCLEAR PHYSICS
K-STRUCTURES OF THE CSM WAVE FUNCTIONS OF 164Er96 AND 166Er98
LIAO BO-QIN, LIN XIN-WEI
1991, 40 (11): 1741-1748. doi: 10.7498/aps.40.1741
Abstract +
The K-structures of the CSM wave functions in 164Er96 and 166Er98 were analyzed in the represention, the bases of which are characterized by the quantum numbers N,π,r,v,K,E1. The K-structure becomes complex as ω increases and the system becomes axially asymmetric. The calculation shows that the K-structure of the yrast band in 164Er96 is very similar to that in 166Er98, but the K-structure of the yrare band in 164Er96 is quite different from that in 166Er98.
ATOMIC AND MOLECULAR PHYSICS
PERTURBATION-ITERATION APPROACH TO ATOMIC PROCESSES IN STRONG LIGHT FIELDS
CHEN BAO-ZHEN
1991, 40 (11): 1749-1754. doi: 10.7498/aps.40.1749
Abstract +
Starting from the space-translated version of Schr?dinger equation of H-atoms in the laser fields with circular polarization, the features of the dressed coulomb potential are analyzed, a small expansion parameter is found and a perturbation-iteration method is presented. Then the zero to second order approximation equations of Floquet-Schr?dinger equation are derived It is shown that the above-mentioned expansion in the small parameter makes the iteration method to give a correct result. Furthermore, the advantages of the approach are qualitatively displayed by a brief comparison of the results given in this paper with the previous results.
ABOVE-THRESHOLD-IONIZATION BY MULTIPHOTON ABSORPTION OF ATOM UNDER SHORT LASER PULSE
ZHANG WEN-QING, TAN WEI-HAN
1991, 40 (11): 1755-1764. doi: 10.7498/aps.40.1755
Abstract +
The Above-threshold-ionization(ATI) Spectrum of electrons produced by multiphoton absorption of atom has been obtained with spatial Gauss and temporal Sech shape of the incident laser pulse. It is found that our model can explain many phenomena such as peak suppression and switching. In addition, what is more important is that we can explain the red shift of the peaks decreases to zero gradually, as the pulse width changes from short to long pulse regime.
ALUMINIUM XUV SPECTRA EXCITED IN A LINE FOCUS LASER——PRODUCED PLASMA
FANG QUAN-YU, ZOU YU, XU YUAN-GUANG, HE AN, HE SHAO-TANG, CHUNYU SHU-TAI
1991, 40 (11): 1765-1770. doi: 10.7498/aps.40.1765
Abstract +
Aluminium targets were irradiated by line focus laser. We observed spectra of high ioni-zation states in the range of VUV. By means of Cowan program for atomic energy level, we caleulated the wavelength and gf value of different ionization state and identified 140 spectra lines.82 new spectra lines were found.
L-SUBSHELL IONIZATION OF Tb, Er AND Lu BY 0.2-1.2 MeV INCIDENT PROTONS
MA SHU-XUN, YANG KUN-SHAN, ZHANG HUA-LIN, CHEN XI-MENG, LIU ZHAO-YUAN
1991, 40 (11): 1771-1775. doi: 10.7498/aps.40.1771
Abstract +
Rare earth elements Tb, Er and Lu were bombarded by protons with energies of 0.2-1.2 MeV, L-subshell ionization cross sections were obtained. Experimental ionization cross sections were compared with the predictions of the ECPSSR theory.
ANALYSES AND MEASUREMENTS OF THE PERFORMANCE PARAMETERS OF THE HEXAPOLE MAGNET STATE-SELECTING SYSTEM
MEI GANG-HUA, ZHU XI-WEN, HUANG GUI-LONG
1991, 40 (11): 1776-1785. doi: 10.7498/aps.40.1776
Abstract +
Taking into account the location, size and also the shape of the defector, we calculated the values of the selectivity and the effective transmittance solid angle of the hexapole magnet system, and compared the results with those of the previous method. The dependence of the selectivity and the effective transmittance solid angle on various experimental parameters, and the ways to improve the performance of the hexapole magnet system were discussed. The selectivity was measured by laser-induced fluorescence (LIF) and the results were in good agreement with the theoretical ones.
CLASSICAL AREA OF PHENOMENOLOGY
MOVING REFRACTIVE-INDEX PHASE GRATING AND BACKWARD PHOTOREFRACTIVE SCATTERING
LING ZHEN-FANG, LIU SI-MIN, GUO RU, ZHANG GUANG-YIN
1991, 40 (11): 1786-1791. doi: 10.7498/aps.40.1786
Abstract +
According to Kukhtarev photorefractive theory, spontaneous generated moving refractive-index phase grating and strong backward photorefractive scattering produced by the phase grating in LiNbO3: Fe crystals are analysed.
AMPLITUDE SQUEEZING OF LIGHT FIELD IN CAVITY
CAO CHANG-QI, LIU ZHENG-DONG, D. L. LIN
1991, 40 (11): 1792-1798. doi: 10.7498/aps.40.1792
Abstract +
In case the speed v of the atoms flying scross the cavity can be exactly adjusted, the light field originally in the cavity may be built into amplitude-squeezed state by adjusting the speed v to the preassigned value. It is also capable to make the photon distribution to have several peaks.
GENERATION OF SQUEEZED STATE LIGHT FROM LASERS VIA NON-DEGENERATE BACKWARD FOUR WAVE MIXING IN LASER CAVITIES
LIU SHANG-QING, XIA YU-XING
1991, 40 (11): 1799-1808. doi: 10.7498/aps.40.1799
Abstract +
A scheme is suggested in this paper, by which squeezed state light can be radiated from lasers directly via non-degenerate backward four wave mixing in laser cavities. Full quantum theory calculations predict that the output light shows good squeezing.
COUPLING OF MELTING-SOLIDIFICATION PHASE CHANGE CONVECTION WITH FLOATING ZONE CONVECTION UNDER MICROGRAVITY
XIONG BIN, TANG ZE-MEI, HU WEN-RUI
1991, 40 (11): 1809-1817. doi: 10.7498/aps.40.1809
Abstract +
A finite element algorithm is used to analyze the process of floating zone Gystal growth under microgravity. The effect of phase change convection coupled with surface tension convection is considered. The results show that the rate of crystal growth is very important. The single-crystal-melt interface is steeper than the feed-melt interface during the process of crystal growth. When the rate exceeds a critical value, the Marangoni vortex nearby the feed-melt interface will become so large that a secondary vortex exists.
PROGRESSIVE WAVES AS SOLUTIONS TO VARIOUS NO NLINEAR WAVE EQUATIONS
TANG SHI-MIN
1991, 40 (11): 1818-1826. doi: 10.7498/aps.40.1818
Abstract +
Progressive waves expressed by rational combination of elliptic functions in general and solitary waves, solitons and kinks in special cases are found as solutions to various nonlinear wave equations.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
A STUDY OF ELECTRONIC CHARACTERIZATION IN MOLECULAR BEAM EPITAXIALLY GROWN GaAs ON Si
ZHOU JIE, LU LI-WU, HAN ZHI-YONG, LIANG JI-BEN
1991, 40 (11): 1827-1832. doi: 10.7498/aps.40.1827
Abstract +
The electronic characteristics of GaAs grown on Si by molecular beam epitaxy(MBE) has been examined by studying the diode characteristics and deep level transient spectroscopy (DLTS) of Schottky barriers. l-V characteristics of samples show the existence large leakage current. Post-growth rapid thermal annealing(RTA)has been found to be able to significantly improve the diode behaviour. The reverse current in the as-grown material shows a very weak temperature dependence, indicating that its origin is not thermoionic emission or generation-recombination currents. We think that a large part of this current is due to defect-assisted tunneling, which is reduced by RTA. DLTS spectra show that Ec-0.41eV and Ec-0.57eV electron traps are observable. The former is located near the GaAs-Si interface probably, the latter relates to the well-known electron trap M5 typical of MBE GaAs.
RELATION BETWEEN THE ANDERSON TRANSITION ZONE AND ENERGY OF THE AUBRY MODEL
SUN JIN-ZUO, WANG CHUAN-KUI, WANG JI-SUO
1991, 40 (11): 1833-1839. doi: 10.7498/aps.40.1833
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On the basis of having proved that there exists the Anderson transition zone in the Aubry model of one-dimensional incommensurate systeme, we further study the relation between the Anderson transition zone and energy. Our numerical results indicate that the Anderson transition zone of the eigenstates in higher energy region is located in the range of lower values of the potential strength V, while, the Anderson transition zone of the eigenstates in lower energy region is located in the range of higher values of V.
ADSORPTION OF ALKALI METAL ON GaAs(110) SURFACE
QIAO HAO, ZHANG KAI-MING
1991, 40 (11): 1840-1845. doi: 10.7498/aps.40.1840
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In the present work, adsorptions of Li,Na,K,Cs on GaAs(llO) surface are studied. Both the ideal and the relaxed surface are considered. The calculations are carried out by using the charge self-consistent EHT method with a cluster model. The results indicate that the surface atoms tend to the ideal configuration after adsorption, and the alkali atom lies at the symmetric plane perpendicular to the surface and crossing the surface Ga atoms along the [001] direction. The Fermilevel is located about 0.7eV above the valence band maximum, which is contributed by the interaction between the surface Ga atoms and the alkali atom, while in the valence band, the alkali atom is bonded mostly with the surface As atoms.
MECHANISM FOR THE DELAY OF DESTRUCTIVE BREAKDOWN IN TCE OXIDE FILMS
LI GUAN-QI, HUANG MEI-QIAN, LIU BAI-YONG, Y. C. CHENG
1991, 40 (11): 1846-1854. doi: 10.7498/aps.40.1846
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This paper study the delay of destructive breakdown and its mechanism on SiO2 films by TCE treatment. The result show that the breakdown current capacity increase with increasing the TCE flow-rate, treatment time and temperature, and reducing the oxygen partial pressure. However, excessive quantity of the TCE flow-rate and prolonging of treatment time make the breakdown characteristics degradation begin to appear. The results also indicate, the increment of breakdown current capacity is associate with the increment of density of electron trap in SiO2 films. In this paper, we propose a breakdown model of "low barrier point-electrical field enhanced" which involve three processes of mutual reinforcement, and consider for the first time the effect of H2O in TCE oxidation on the breakdown characteristics. The restrained function of electron trap on electrical field enhanced in low barrier point is quoted, and analyze the mechanism for delay of destructive breakdown in TCE oxides.
STUDY ON HIGH-FIELD ELECTRON TRAPPING AND DETRAPPING PROPERTY IN THIN SiOx Ny FILMS
YANG BING-LIANG, LIU BAI-YONG, Y. C. CHENG, H. WONG
1991, 40 (11): 1855-1861. doi: 10.7498/aps.40.1855
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The electron trapping at high-field and detrapping in thin thermally nitrided silicon oxide (SiOxNy) films are studied in the present work. It is observed that when the nitridation degree is the lighter, with the increasing of the nirridation time the effective electron trap surface concentration in the films increases rapidly, and the detrapping ratio of trapped electrons is almost zero and independent of the shorting time for samples and the strength (until 8MV/cm) and duration of application of external reverse field, and the depth of the electron trap level is the deeper; when the nitridation degree is the heavier with the further increasing of the nitridation time the effective electron trap surface concentration decreases and the depth of electron trap level becomes shallow gradually, and the detrapping ratio of trapped electrons gradually increases and is approximately dependent exponentially on the strength and duration of time application of external reverse field and is almost independent of the shorting time for the samples.
CHANGE OF ELECTRONIC STRUCTURES CAUSED BY LOCAL SUBSTITUTION OF Zn FOR Cu IN YBa2Cu3O7 MATERIAL
WANG CHENG-ZHANG, WANG HUAI-YU, ZHANG LI-YUAN
1991, 40 (11): 1862-1868. doi: 10.7498/aps.40.1862
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Using Recursion method, we have studied the change of electronic structures caused by local substitution of Zn for Cu(2) in YBa2Cu3O7 material. It is found that the substitution has important effect on the properties of the substituted site and its neighbours, which include the partial wave densities of states, the type and strength of bonds, and the atomic valence of sites. On the basis of calculations, we analyze the mo ement of charge and believe that the decrease of hole concentration in CuO2 layers is the dominant factor in lowering the superconducting transition temperature of YBa2Cu3O7 when Zn substitutes Cu in small amounts.
STUDY ON Sb-DOPED Bi SYSTEM SUPERCONDUCTOR
BAI PEI-GUANG, LIU JIAN
1991, 40 (11): 1869-1874. doi: 10.7498/aps.40.1869
Abstract +
In the samples of Sb proper doping Bi-Sr-Ca-Cu-O system, the content of the high temperature phase (110K phase) is obviously much higher than that of the Sb-free samples'. Sb has a function of accelerating the formation of the high Tc phase. For the nominal composition of Bi2-xSbxSr2Ca2.5Cu3.7Oy x = 0.1 is most beneficial to the formation of the high Tc phase, After quenching in liquid nitrogen and annealing at low teperatures, it is found that the low Tc phase (80K phase) is firstly formed when the samples are sintered at 865℃, then the low Tc phase changes to the high Tc phase, until all materials become the high Tc phase eventually. The value of Tc increases continuously with time lasting. If annealed at lower em-perature, the high Tc phase will change to the low Tc phase. Based on this discovering, after sintering at high temperature, for a long time, fast cooling to a low temperature, annealing for some time, then naturally cooling to room temperature, we have successfully prepared the high Tc single phase superconductor with zero resistance temperature 113K.
ON THE RELATION BETWEEN THE IN-PLANE ANISOTROPY AND THE TECHNICAL MAGNETIC PROPERTIES OF AS-PREPARED AMORPHOUS ALLOY RIBBONS
HE KAI-YUAN, XIONG XIANG-YUAN
1991, 40 (11): 1875-1878. doi: 10.7498/aps.40.1875
Abstract +
The in-plane magnetic anisotropy constants of Fe40Ni40P12B8 and (Fe0.1CO0.5Ni0.4)78Si6B16 amorphous alloy ribbons in the as-quenched and annealed state have been measured with the torque magnetometer and the work of magnetization methods. The results show that the main part of the anisotropy constant measured by the torque magnetometer method for the as-quenched samples does not change after annealing and this part of anisotropy almost produces no influence on the magnetization curve.
POSITRON ANNIHILATION STUDY ON DEFORMATION OF HIGH PURITY IRON UNDER DIFFERENT STRAIN RATE
WU YI-CHU, TIAN ZHONG-ZHUO, CHANG XIANG-RONG, XIAO JI-MEI
1991, 40 (11): 1879-1882. doi: 10.7498/aps.40.1879
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Variation of S-parameter with the strain (S-ε curve) under different strain rate are investigated by combining Doppler broadening measurement with slow tensile test. Experimental results are as follows:1. Under slow strain rate, the S-ε curve in high purity iron does not tend to saturation. The slower the strain rate is, the more evident the "non-saturation phenomenon".2. Variations of S-ε curve with strain rate are attributed to the different configuration of dislocation distribution under different strain rates.3. As high purity iron is deformed, the increment of S-parameter depends not only on dislocation density but also on vacancy concentration, and we attibute the so called "non-saturation phenomenon" of S-ε curve to the strain induced vacancies.
POSITRON ANNIHILATION STUDY ON THE INTERACTION BETWEEN HYDROGEN ATOMS AND DEFECTS IN COLD-ROLLED NICKEL
WU YI-CHU, TIAN ZHONG-ZHUO, CHANG XIANG-RONG, XIAO JI-MEI
1991, 40 (11): 1883-1887. doi: 10.7498/aps.40.1883
Abstract +
The interaction between hydrogen atoms with defects in coldrolled nickel is investigated by Doppler broadening measurement. Experimental results show that the S-parameter in cold-rolled-hydrogen-charged nickel increases as compared with that of hydrogen-free cold-rolled nickel. And the increament of S-parameter depends on vacancy concentration, being almost independent of dislocation density. It is suggested that hydrogen atoms can act as centers of vacancy agglomeration, leading to the formation of vacancy cluster.
ARUPS INVESTIGATION OF CO COADSORPTION WITH K ON W(100) SURFACE
BAO SHI-NINO, ZHU LI, XU YA-BO
1991, 40 (11): 1888-1892. doi: 10.7498/aps.40.1888
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Hel ultraviolet photoemission studies of CO coadsorption with different K coverages on W (100) surface show that the 1π/5σ level of α-CO shifts from 8.6eV to 9.3eV relative to the Fermi level while the K coverages increase, this indicates the increase of electron backdonation into 2π* of α-CO. Two independent peaks are found around 5.5 eV (Characteristic of β-Co), one is at 5.2eV, another is at 6.0eV. The peak at 5.2eV grows with increasing K coverages, its energy position is the same as that of O coadsorption with K on W(100) surface, this suggests that K forms bond to O of β-CO.
Sn4+ MONTMORILLONITE——A Sn4+ CATION CONDUCTOR
WANG YI-ZHEN, WANG DA-ZHI, ZHANG DAO-YUAN, ZHAO JIAN-XING, HE XIANG-YONG
1991, 40 (11): 1893-1986. doi: 10.7498/aps.40.1893
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A four valence cation conductor Sn4+ Montrnorillonite has been obtained in our lab. The valence state of migrating ion Sn4+ was confirmed with Mossbauer spectroscopy. Its electron eonductivity and AC conductivities were 5.1×10-7 and 1.5×10-4(S/cm) respectively. Some Sn/MnO2 batteries were made using this solid electrolyte with 1.2V OCV and 5mA short current for 13mm×3mm size.