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Vol. 41, No. 4 (1992)

1992-02-20
Topics
GENERAL
SUPERCOHERENT STATES AND BERRY'S PHASE
CHEN CHENG-MING, XU DONG-HUI
1992, 41 (4): 529-534. doi: 10.7498/aps.41.529
Abstract +
Supercoherent states as the result of acting of displacement operator on a supersymmetric hamiltonian are introduced and discussed. Berry's phase is calculated for coherent states as their parameters are taken to be varying adiabatically.
A METHOD FOR FINDING THE EIGENVALUE OF QUANTUM GROUND STATE
ZHU DONG-PEI, SHI MING-JUN, CHEN YIN-HUA
1992, 41 (4): 535-542. doi: 10.7498/aps.41.535
Abstract +
With an integral transformation, the energy eigenvalue problem of a quantum system is converted into the solving of a non-linear Riccati equation. It is easy to find the ground state energy and the corresponding wavefunction. The relation with usual factorization method is discussed. The ground states of various quanum systems are calculated to show the advantage of this new method.
STATISTICAL ANGLE OF QUANTUM MIXED STATES
ZHU DONG-PEI, WANG REN-CHUAN, WANG GUI-XING
1992, 41 (4): 543-549. doi: 10.7498/aps.41.543
Abstract +
The statistical angle between quantum pure stages has been generalized to quantum mixed states. For the case of a single mixed state, it leads to a concept of divergence angle. A criterion for pure state is obtained. In the quantum measurement the information function is the squared cosine of statistical angle between the quantum system and the instrument. The entropy increase during the measurement process appears to be the expanding of the divergence angle.
SCALING BEHAVIOR IN WEAK-COUPLED COMPLETE MAPS
LU YAN-NAN, DING E-JIANG
1992, 41 (4): 550-553. doi: 10.7498/aps.41.550
Abstract +
The first Lyapunov exponent for a one-dimenssional unimodal map system with very weak coupling strength is calculated. The numerical results show that there is a universal scaling relation between the first Lyapunov exponent and the coupling strength.
THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
A STUDY FOR THE INFLUENCE OF CH2Cl2,CHCl3, CCl4 ON THE PHOSPHATIDYLCHOLINE LIQUID-CRYSTAL STRUCTURE BY MEANS OF THE SMALL- ANGLE X-RAY SCATTERING
SUN RUN-GUANG, WANG DE-HUA, WANG ZI-HAO, ZHANG JING
1992, 41 (4): 554-560. doi: 10.7498/aps.41.554
Abstract +
This article presents the results of the research using the mothod of SAXS(small angle X-ray scattering) to investigate the influence of CH2Cl2, CHCl3 and CCl4 respectively on the liquid-crystal structure of phosphatidylcholine (PC). Experiments show the following phenomena: The structure of the PC liquid-crystal phase is primarily influenced by space-spinning electronic cloud density distribution of CH2Cl2, CHCl3 and CCl4. The compounds that their space-spinning electronic cloud density distribution assume spinning ball or spinning oval ball in shape all give the mechanism that makes the PC liquid-crystal state to form lamellar and hexagonal phase. And the compounds that their space-spinning electronic cloud density distribution assume spinning taper in shape give the mechanism that makes the PC liquid-crystal state to form hexagonal Ⅱ phase.
NUCLEAR PHYSICS
ON THE SATURATION PROPERTIES AND THE LIQUID-GAS TRANSITION OF FINITE NUCLEAR MATTER
WANG NENG-PING, YANG SHAN-DE
1992, 41 (4): 561-567. doi: 10.7498/aps.41.561
Abstract +
The saturation properties and the liquid-gas transition of finite nuclear matter are investigated with the Skyrme effective interaction and the Coulomb interaction in the framework of Hartree-Fock theory. The critical temperature for liquid-gas transition of finite nuclear matter is found to be around 12 MeV.
OPTICAL RESONANCE METHOD FOR MEASURING ION ENERGY
SHI WEI, LU FU-QUAN, WU SONG-MAO, TANG JIA-YONG, YANG FU-JIA
1992, 41 (4): 568-572. doi: 10.7498/aps.41.568
Abstract +
An optical resonance method for measuring ion energy has been suggested. The experimental details are described. The method relates the resonant oprical transition of ions and the ion energy through the Doppler effect. The method can be applied in the energy range of leV-100 MeV, and its accuracy is expreted to reach 5×10-5 near energy of 30 keV. We have measured the 142Nd+-ion energy by this method and the result is fairly good.
CLASSICAL AREA OF PHENOMENOLOGY
MEASUREMENTS OF BEAM OPTICAL CHARACTERISTICS OF NEON-LIKE GERMANIUM X-RAY LASER
HE SHAO-TANO, HE AN, CHUNYU SHUTAI, ZHANG QI-PEN, GU YUAN-YUAN, NI YUAN-LONG, YU SONG-YU, ZHOU ZHENG-LIANG
1992, 41 (4): 573-577. doi: 10.7498/aps.41.573
Abstract +
The spatial profiles in the horizontal and vertical direction of lasing line intensity of neon-like germanium were measured. For a 20mm long plasma of 102μm lateral dimension, the main beam in the horizontal direction is found to exhibit an angular divergence of 12 mrad with a offset displaced 8 mrad from the plasma axis and the beam angular divergence in vertical direction is about 22 mrad. In addition, the characteristic of beam optics of the double-pass amplification was diagnosted using a Mo/Si multilayer mirror.
THE ATOM SQUEEZING EFFECT FOR OFF-RESONANT TWO-PHOTON OPTICAL BISTABILITY IN BAD-CAVITY CASE
S. SACHUIF, HU GANG
1992, 41 (4): 578-586. doi: 10.7498/aps.41.578
Abstract +
The atom squeezing effect for off-resonant two-photon optical bistability in bad-cavity limit is studied by means of Fokker-Planck equation of the generalized Wigner distribution. The distribution of the squeezing region in Δ-θ plane is described. As atom-detuning is sufficiently large, the squeezing effect of the atom operator R2 may appear.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
THE EFFECT OF ION CYCLOTRON RESONANCE HEATING ON LOWER HYBRID CURRENT DRIVE IN TOKAMAK PLASMA
SHEN LIN-FANG, YU GUO-YANG
1992, 41 (4): 587-593. doi: 10.7498/aps.41.587
Abstract +
A possible process occurring when ICRF wave for second harmonic heating of deuterium and LH wave for current drive are launched simultaneously into a D-T plasma in tokamak reactor is studied. The particle absorption of LH wave is calculated using linear theory. In combination with ICRH the LH-current drive efficiency is reduced. It decreases with increasing ICRF power due to the competing absorption of LH power by energetic D+. The absorption of LH wave by the energetic deuterium can be lowered by raising the LH wave frequency.
HYDROGEN RECYCLING IN HL-1 TOKAMAK
PENG LI-LIN, XU GUANG-BI, YUAN CHENG-JIE, CAO ZENG, HUANG KE-QIANG, ZHANG SHU-XUN, YAN DONG-HAI
1992, 41 (4): 594-602. doi: 10.7498/aps.41.594
Abstract +
The recycling behaviours and their effects on the particle confinement under various operational conditions in HL-1 device are studied systematically. Using the particle balance equation and a hydrogen recycling model proposed by Howe, we estimated the global recycling coefficient R(t) from the data of Hα emission and others. The fueling ratio introduced by Ehrenberg is adopted to analyse the wall pumping and the wall fuelling as the wall/limiter condition or the kinds of inlet gas are altered. The phenomena of particle release after different plasma discharges are also observed and compared by using the quadrupole mass-spectrometer.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
THE INFLUENCE OF THE DEVIATION ANGLE ON THE ROCKING CURVE AND ITS WIDETH
LI CHAO-RONG, MAI ZHEN-HONG, CUI SHU-FAN
1992, 41 (4): 603-608. doi: 10.7498/aps.41.603
Abstract +
The influence of the deviation angle of the sample surface from the exact crystalline surface on the X-ray double crystal rocking curves an{d its full width at half maximum (FWHM) were investigated based on the X-ray dynamical diffraction theory. The results show that when the sample surface has a deviation from the exact crystalline surface, the profile of rocking curves and their FWHMs are dependent on the incident angle and the direction of X-ray beam. Moreover, with the decreasing of the incident angle, the FWHM of rocking curve increases, and the reflection peaks shift to the high angle region. This influence becomes more significant when the asymmetrical diffraction is used.
PHASE TRANSITION OF COMB POLYMER NEMATIC LIQUID CRYSTAL
LIU HONG
1992, 41 (4): 609-616. doi: 10.7498/aps.41.609
Abstract +
The Hamiltonian of comb polymer nematic liquid crystal molecule is constructed by using the interaction model of nematic liquid crystal molecule proposed by Freiser and the mean field theory. The self-consistancy equations of order parameters are derived and the phase transitions from isotropics to uniaxial nematics, uniaxial to biaxial nematics are obtained. The results show that when the repulsion in coupling term of backbone and side chain getting greater, the nematic field of the stronger one between those of backbone and side chain getting stronger, the uniaxial-biaxial phase transition temperature will rise and the phase transition will gradually change from first order to second order phase transition.
A MASS TRANSFER MODEL FOR THE PLASMA DEPOSITION PROCESS IN AXIAL-FLOW REACTOR
LIU ZU-LI, ZHU DA-QI, SONG WEN-DONG, CHEN JUN-FANG
1992, 41 (4): 617-622. doi: 10.7498/aps.41.617
Abstract +
A kinetic model for the glow discharge plasma deposition process in the axial-flow reactor is proposed. In particular, the realtionships between the deposition characteristics (i.e., generation rate, generation frequency, deposition rate, and gas efficiency) and the process parameters (gas flow rate and gas pressure) are examined by numerical modeling technique. Some results has been explained.
EXTENDED ELECTRONIC STATES IN A CLASS OF ONE DIMENSIONAL QUASIPERIODIC SYSTEMS
YOU JIAN-QIANG, ZHONG JIAN-XIN, YAN JIA-REN, YAN XIAO-HONG
1992, 41 (4): 623-632. doi: 10.7498/aps.41.623
Abstract +
Using the dynamical-map method, we study the electronic properties for diagonal and off-diagonal tight-binding model in a class of one-dimensional quasiper-iodic systems. These systems are associated with the generalized Fibonacci sequences S∞ given by the recursion relation Sl+1=Sl2j-1Sl-12i for l≥1 with two initial sequences S0 and S1, where i and j are positive integers. Analytical treatments show that the extended electronic states for these one-dimensional quasiperiodic sequences really exist.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
POSITRON ANNIHILATION CHARACTERISTICS OF HYDRO-GEN-VACANCY COMPLEX IN ALUMINUM
WANG XIAO-GANG, ZHANG HONG
1992, 41 (4): 633-639. doi: 10.7498/aps.41.633
Abstract +
The positron annihilation characteristics of one hydrogenvacancy complex and many hydrogens-vacancy complex in aluminum have been calculated, using the discrete variational method, embedded-cluster model based cm the first-principles and a fully-three-dimensional numerical relaxation technique. The possible location of hydrogen atom in the single vacancy in aluminum is discussed.
PHOTOLUMINESCENCE OF ZnSe-ZnS STRAINED-LAYER SUPERLATTICES
JIANG FENG-YI, PAN CHUAN-KANG, FAN GUANG-HAI, FAN XI-WU
1992, 41 (4): 640-648. doi: 10.7498/aps.41.640
Abstract +
The photoluminescence (PL) emission spectra of ZnSe-ZnS strained-layer surerlattices (SLS) grown by atmospheric pressure metal organic chemical vapor deposition (AP-MOCVD) have been studied in this paper. With the high density excitation (N2-Laser 337.1nm), the PL of the SLS consist in only one emission peak due to the n = 1 heavy hole excitons recombination, and with the low density excitation (high pressure Hg-Lamp 365.nm) the PL consist of both the band-edge emission and the deep-centre emission. One gap-edge emission peak without the deep-centre emission have been observed in the low-excitation PL, and the sample was thought to have good crystaline quality. The subbands of ZnSe-ZnS SLS were calculated using the theoies of the stress-induced baud structures and the Kronig-Penney band model. The two emission peaks, the energy of which are greater than the energy-gap of ZnSe single crystal films in the absence of strain, were observed in the PL spectra of ZnSe-ZnS SLS for the first time. According to the subband calculation, the two peaks were thought to be caused by the transitions between the n= 1 electronic subband and the n= 1 heavy, light holes' subbands, respectively.
THE FORMATION MECHANISM OF HIGH-Tc PHASE IN Bi-BASED SUPERCONDUCTOR
QIU XIN-LIANG, LI CHENG-REN, XIN MIAN-RONG, LUO CHANG-XUN
1992, 41 (4): 649-654. doi: 10.7498/aps.41.649
Abstract +
In this paper, the formation process of high-Tc phase in Bi-based supercondutor is investigated by X-ray diffraction etc. The high-Tc phase might be formed in the following manner. At first, the nuclei of hig-Tc (2223) phase are formed by the reaction of Sr-Ca-Cu oxide with low-Tc (2212) phase; Then the nuclei of 2223 phase grows, following the manner of ordinary crystal growth. There are two ways to form Sr-Ca-Cu oxide. One is accomplished by solid state reaction between Ca2CuO3 and Ca3(1-x)Sr3xCu5O8, and the other by liquid-state reaction of Ca2PbO4, 2212 phase and CuO. The liquid-state reaction rate is much quicker than that of solid state reaction. So, the rate of formation of 2223 nuclei can be accderated in liquid-state reaction. Based on this mechanism, we propose that Pb can only accelerate the nucleation of 2223 phase and exert no significant influence on the growth of 2223 phase.
X-RAY PHOTOELECTRON SPECTROSCOPY STUDY ON THE ELECTRONIC STATE OF Gd-DOPED 2212 SINGLE CRYSTAL IN Bi-BASED SYSTEM
ZHANG QI-RUI, WANG NAN-LIN, SHA JIAN, WANG XI-QING, QIAN YI-TAI, CHEN ZU-YAO
1992, 41 (4): 655-660. doi: 10.7498/aps.41.655
Abstract +
XPS measurements have been carried out to study the difference in the electronic state between the pure 2212 single crystal and the Gd-doped 2212 single crystal in Bi-based system. Experimental results show that the suppression of superconductivity by Gd doping is caused by the hole filling in the O2p orbital. The problems, such as that about the ratio of the intensity of the satellite peaks to that of main peak (Is/Im) the physical property of Bi-O layer and the contribution to the density of state (DOS) at Er for the Bi-based 2212 phase have also been discussed.
NEAR RESONANT RAMAN SCATTERING FROM GaAs/AlAs SUPERLATTICES
HAN HE-XIANG, WANG ZHAO-PING, LI GUO-HUA, JIANG DE-SHENG, K. PLOOG
1992, 41 (4): 661-667. doi: 10.7498/aps.41.661
Abstract +
This article presents the results of near resonant Raman scattering measurement of GaAs/ AlAs superlattices at room temperature. A strong enhancement of GaAs LO phonon even modes resulted owing to dipole allowed Fr?hlich interaction in superlattices. Similar to the previous results, the LO phonon even modes in polarized configuration is observed. In contrast to the previous works, however, what we observed in depolarized configuration is the LO phonon odd modes instead of even modes. And it is confirmed that the selection rules of near resonant Raman scattering from LO phonons in this kind of superlattices is the same as that of off resonant scattering. From the second-order Raman scattering, it is confirmed that polarized second-order Raman scattering spectra consist of overtone and combinations of two even modes and depolarized second-order Raman scattering spectra consist of combinations of an even mode and an odd mode. Our experimental results coincide with the predictions using recently developed Huang-Zhu model. A brief discussion on interface modes and their combination with confined modes are also presented.
STRUCTURAL TRANSITIONS AND FREE-VOLUME PROPERTIES OF PMMA POLYMER STUDIED BY POSITRON ANNIHILATION
LIN DONG, WANG SHAO-JIE
1992, 41 (4): 668-674. doi: 10.7498/aps.41.668
Abstract +
Positron lifetime and Doppler broadening of annihilation radiations have been measured for PMMA polymer in temperature range from 20℃ to 150℃. The O-Ps annihilation and Doppler broadening data consistently show the structural changes in PMMA. The transitions at 48℃ and 108℃ are attributed to the β transition and glass transition of PMMA respectively. An anomalous change of o-Ps lifetime and intensity around 84℃ is found to be the result of the mergence among some freevolume voids. The results of Doppler broadening measurement also give the information about the variations of degree of structural order. The temperature dependences of size and concentration of free volume in PMMA are estimated from the experimental o-Ps annihilation parameters.
INFLUENCE OF CHEMICAL ETCHING AND SULFIDE TREATMENT ON InSb(111) SURFACES
LU CHUN-MING, LI ZHE-SHEN, DONG GUO-SHENG, REN JING, GONG YA-QIAN
1992, 41 (4): 675-682. doi: 10.7498/aps.41.675
Abstract +
The chemical etched and (NH4)2S-treated InSb(lll) surfaces have been studied using Auger electron spectroscopy and X-ray phctoelectron spectroscopy. It is found that after etching in the CP-4 solution the InSb surfaces are covered by a native oxide overlayer in which the amounts of Sb oxide are obviously more than In oxide. The native oxide layer on the InSb surfaces is completely removed by sulfide treatment and then a sulfide passivation layer forms on the sample surfaces.
ELECTRONIC SPECTROSCOPY STUDIES OF P2S5/NH4OH TREATED GaAs(100) SURFACE
ZHONG ZHAN-TIAN, LUO WEN-ZHE, MOU SHAN-MING, ZHANG KAI-YAN, LI XIA, LI CHENG-FANG
1992, 41 (4): 683-688. doi: 10.7498/aps.41.683
Abstract +
The microscopic characteristics of the GaAs(100) surface treated with P2S5/NH4OH solution has been investigated by Auger electron spectroscopy (AES) and X-ray photoemission spectroscopy(XPS). AES reveals that only phosphorus and sulfur, but no oxygen, are contain-ed in the interface between passivation film and GaAs substrate. Using XPS, it is found that both Ga2O3 and As2O3 on the GaAs surface are removed by the P2S5/NH4OH treatment, moro-ver, gallium sulfide and arsenic sulfide are formed. The passivation film results in a reduction of surfacer state density and improving both electronic and optical properties of GaAs surface.
PHOTOELECTRON SPECTROSCOPY STUDIES OF α-P/GaAs (100) INTERFACES
LU XUE-KUN, HOU XIAO-YUAN, DONG GUO-SHENG, DING XUN-MIN
1992, 41 (4): 689-696. doi: 10.7498/aps.41.689
Abstract +
The room temperature deposited α-P/GaAs(100) interfaces have been studied by XPS, UPS, and LEED. The results show that P is adsorbed as clusters on the surface of GaAs at the initial stage of the interface formation, α-P film is formed as the deposition amount is further increased. The valence structures of the films so obtained are similar to those of plasma deposited α-P:H films. There are about one monolayer of P atoms bonded to Ga atoms of the substrate at the interface, α-P overlayer results in 0.2 eV lowering of GaAs surface barrier.