Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
Volume 64, Issue 8
Displaying 1-50 of 53 articles from this issue
  • Hideaki Ujino, Miki Wadati
    Subject area: Mathematical methods in physics.
    1995 Volume 64 Issue 8 Pages 2703-2706
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    A construction of a new series of orthogonal symmetric polynomialsassociated with the quantum Calogero model is reported. The orthogonalpolynomials correspond to the simultaneous eigenstates of theconserved operators. The eigenvalue of the first nontrivial conservedoperator is conjectured. Explicit forms are shown for some of thepolynomials.
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  • Kimiaki Konno, Hiroshi Kakuhata
    Subject area: Mathematical methods in physics.
    1995 Volume 64 Issue 8 Pages 2707-2709
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    The general form of the integrable dispersionless equation is solvedby the inverse scattering method. Soliton solutions consist of growingsolitons, decaying solitons and stationary solitons. Interaction amongthem and their properties are considered.
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  • Yoshihiko Nonomura, Yukiyasu Ozeki
    Subject area: Statistical physics and thermodynamics.
    1995 Volume 64 Issue 8 Pages 2710-2713
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Ground-state properties of the two-dimensional S=1/2 random Heisenbergmodels are investigated by the exact-diagonalization method. The phasediagram of the bond-random model (the ± J model) is the same as thatof the corresponding Ising spin glass model, in spite of quantumfluctuation. In the site-random model, the spin glass phase exists atleast in the ferro-rich case. In comparison with the correspondingIsing model, the Néel phase of this model becomes much narrower inthe ferro-rich case, while it is comparable in the antiferro-richcase.
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  • Hisashi Okamoto
    Subject area: Fluid dynamics.
    1995 Volume 64 Issue 8 Pages 2714-2717
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    A family of exact solutions of the stationary Navier-Stokes equationsare given. They satisfy the Navier-Stokes equations outside a cylinderand tend to a certain inviscid explicit Euler flow at infinity. Oursolutions are generalizations of those obtained by Wang, Stuart, Tamada, and Dorrepaal.
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  • Leonid G. Bruskin, Teruo Tamano
    Subject area: The physics of plasmas and electric discharges.
    1995 Volume 64 Issue 8 Pages 2718-2721
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Surface temperature-driven erosion instability ofplasma-facing material is analytically investigated. It is shown thatfor shallow incidence the influence of temperature disturbanceconsists primarily of growth rate enhancement for the fluctuationswith small wave numbers. For larger incidence angles surfacetemperature-related effects dominate over ion flux-driven depositioninstability. Mean scale of surface roughening is estimated to be1--2, mm.
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  • Osamu Yamamuro, Hiroki Muraoka, Tomoko Ohta, Takasuke Matsuo, Yoshio K ...
    Subject area: Structure of liquids and solids; crystallography.
    1995 Volume 64 Issue 8 Pages 2722-2725
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    A neutron diffraction experiment on the high-temperaturephase of (ND4)2SeCl6 crystal has been performed with atime-of-flight powder diffractometer. The data were collected at 60 Kin the {d}-spacing range 0.6--6Å. The Rietveld refinement revealedthat the crystal has the antifluorite structure (Fm\bar{3m, a=9.8420(1)Å) in which four D atoms of the ND+_4 ion at(1/4, 1/4, 1/4) are preferentially (but not exclusively) orientedtoward the four unoccupied corners of the (1/2× 1/2× 1/2)cube surrounding the cation. The Fourier contour map (F_{obs) of the(111) section suggested that the D atoms are disordered about thepreferential orientations along the crystallographic 3-fold axes, withsubstantial density of the scattering centers distributed off thesymmetry direction. The result is discussed in the light of previousthermodynamic data on the phase transition at 46 K.
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  • Hiori Kino, Hidetoshi Fukuyama
    Subject area: Electron states in condensed matter.
    1995 Volume 64 Issue 8 Pages 2726-2729
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Electronic states of κ-(ET)2X are studiedtheoretically. The effects of the on-site Coulomb interaction anddimer structure have been explored at absolute zero within theHartree-Fock approximation. If Coulomb interaction exceeds somecritical value, localized spins which are antiferromagneticallyordered within a unit cell emerge resulting in reduction of the bandoverlap and eventually leading to the insulating state.
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  • Osamu Narikiyo, Kazumasa Miyake
    Subject area: Electronic transport in condensed matter.
    1995 Volume 64 Issue 8 Pages 2730-2733
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Nested spin-fluctuation theory on the basis of theitinerant-localized duality formalism is applied to athree-dimensional metal with paramagnetic ground state. The resultsfor the resistivity, the Hall coefficient, the specific heat, the spinsusceptibility and the spin-lattice relaxation rate are in qualitativeagreement with their strange behaviors observed in V2-yO3 underpressure which has been thought of as a typical doped Mott insulatorso far.
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  • Nobuo Furukawa
    Subject area: Electronic transport in condensed matter.
    1995 Volume 64 Issue 8 Pages 2734-2737
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    The double-exchange model in infinite dimension is studiedas the strong Hund's coupling limit J→ ∞ of the Kondolattice model. Several quantities such as Green's function and thed.c. conductivity are calculated in analyticalforms. Magnetoresistance in lightly doped La1-xSr_xMnO_3 is reproducedvery well.
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  • Yoshihiro Shimazu, Seiichiro Ikehata, Shun–ichi Kobayasi
    Subject area: Electronic transport in condensed matter.
    1995 Volume 64 Issue 8 Pages 2738-2741
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    We studied small-capacitance single tunnel junctions withvarious tunnel resistances. In order to reduce the environmentaleffect and to observe the Coulomb blockade clearly, we have adoptedhigh-impedance leads which consist of multiple junctions to isolatethe single junction. We observed the gradual weakening anddisappearance of the Coulomb blockade as the tunnel resistance in theabsence of charging effects is lowered below the resistancequantum. As the tunnel resistance increases above the resistancequantum, the zero-bias resistance divided by the tunnel resistancetends to flatten off. The observed dependence of the zero-biasresistance on the tunnel resistance is in good agreement with thetheory of Brown and imánek.
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  • Kazuyoshi Yamada, Yasuo Endoh, Chul–Ho Lee, Shuichi Wakimoto, Ma ...
    Subject area: Superconductivity.
    1995 Volume 64 Issue 8 Pages 2742-2745
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    High-energy pulsed neutron inelastic scatteringexperiments have been performed using single crystals ofLa1.85Sr0.15CuO_4 to study magnetic fluctuations in thesuperconductingphase. A peak centered at the reciprocal point (π, π ) is welldefined below around 120 meV and rapidly damped beyond thisenergy. However, the “ background-subtracted'' scatteringintensities indicate that magnetic signals remain up to around300 meV. These data combined with the results obtained by triple-axisneutron scattering experiments provide the first overall energyspectrum of the dynamical susceptibility in La1.85Sr0.15CuO_4. Theobtained spectrum is much wider than that of YBa_2Cu_3O7-d(d-- 0).
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  • Takashi Sugiyama, Tetsuo Ohmi
    Subject area: Superconductivity.
    1995 Volume 64 Issue 8 Pages 2746-2749
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    We consider a mechanism to stabilize the non-unitary state proposedfor the pairing state of the heavy Fermion superconductor UPt3. Ifthe derivative of the density of states with respect to the energy isfinite at the Fermi surface, the non-unitary superconducting state hasa magnetic moment. The mechanism we consider is concerned with thisproperty and similar to Stoner's theory for ferromagnetism. We find, by constructing the GL free energy, that the following two conditionsare crucial:i) the electron-hole asymmetry of the density of states is ratherlarge; ii) the system is in a nearly ferromagnetic state.
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  • Kazuyuki Matsuda, Yoh Kohori, Takao Kohara
    Subject area: Superconductivity.
    1995 Volume 64 Issue 8 Pages 2750-2753
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    We present measurements of the NQR spectrum and thenuclear spin lattice relaxation rate, 1/T1, of 101Ru insuperconducting CeRu2 from 1.9 K to 10 K. From the NQR spectrum, the electric quadrupole interaction parameters were determined to beν Q=13.2 MHz and η =0.1/T1 varies in proportion totemperature in the normal state, and has the Hebel-Slichter coherencepeak just below the superconducting transition temperature, TC, of6.2 K, and decreases exponentially at low temperatures with theenergy gap of 2Δ=4.0kBTc. 101Ru NQR studyindicates that CeRu2 is an s-wave and strong-couplingsuperconductor.
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  • Nobuo Furukawa
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 8 Pages 2754-2757
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Using the Kondo lattice model with classical spins ininfinite dimension, magnetic phase transition in the perovskite-type3d transition-metal oxide La1-xSrxMnO3 is theoreticallystudied. On the Bethe lattice, the self-consistency equations aresolved exactly. Curie temperatures in the region of double-exchangeferromagnetism 0.1≤ x≤ 0.25 as well as the Nèeltemperature at x=0are well reproduced quantitatively. Pressure effect on the Curietemperature is also discussed.
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  • Satoshi Taniguchi, Takashi Nishikawa, Yukio Yasui, Yoshiaki Kobayashi, ...
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 8 Pages 2758-2761
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Spin susceptibility and spin-lattice relaxation rate of51V nuclear moments of CaV4O9 with tetragonal structure havebeen measured. They exhibit characteristics of spin gap systems. Thisprovides the first example of quasi-two-dimensional spin systems withspin gap.
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  • Hiroki Nakano, Minoru Takahashi
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 8 Pages 2762-2765
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Quantum Heisenberg antiferromagnets in one dimension withlong-range interactions are studied; a Hamiltonian which has dimerstates composed of nearest-neighbor singlet pairs as eigenstates ofthe system is obtained. We also obtain sufficient conditions underwhich the eigenstates are the ground states. We propose a model whichis very similar to the Haldane-Shastry model but has the dimer groundstates.
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  • Hajime Takayama, Hajime Yoshino
    Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1995 Volume 64 Issue 8 Pages 2766-2770
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    We have carried out Monte Carlo simulation on the 3-dimensional isotropic ± J spin glass model, by which the distribution function of relaxation times P(τ ) is extracted from autocorrelation functions of all individual spins in the system. The obtained P(τ ) gives clear evidence for the cluster dynamics due to the Griffiths singularity in a spin glass system as well as for the crossover between the cluster dynamics and the critical dynamics associated with the spin glass transition at Tc(=0).
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  • Yoshimasa Isawa
    Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
    1995 Volume 64 Issue 8 Pages 2771-2775
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Using a tight binding approach, the Green's function for radiation fields (RF) in a resonator is calculated by considering that they are interacting with a vacuum field in an external environment outside the resonator. The general formulas for the rates of the spontaneous and stimulated emission from an atom in an excited state are given, of which the latter is evaluated for an initial state with only one photon. The emission rate is obtained for an arbitrary ratio between the wavelength of RF and the cavity length. The stimulated emission is also controllable by changing an initial one-photon state and an atomic position.
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  • B. Z. Essimbi, A. A. Zibi, A. Zame, T. C. Kofane
    Subject area: Mathematical methods in physics.
    1995 Volume 64 Issue 8 Pages 2777-2781
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Soliton-like excitations with frequencies in the gap of alinear spectrum ar considered for a new type of nonlinear LC circuitrecently introduced by S. Ishiwata {etal}. [J. Phys. Soc. Jpn. 59(1990) 1163]. A nonlinear capacitor whose capacitance depends on thesquare root of the voltage in the shunt branch is composed of twodiodes connected in series but inversely with each other. Numericalresults are obtained which show the existence of a new class oflocalized solitary signals.
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  • Hidetoshi Konno, Hiroyuki Sawahata
    Subject area: Mathematical methods in physics.
    1995 Volume 64 Issue 8 Pages 2782-2794
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    We exemplify the method of nonlinear transformation (NTR)as a powerful tool for obtaining excellent approximate analyticsolution of nonlinear ordinary differential equation. The Duffingoscillators and Brusselator are adopted to demonstrate its usefulnessand suitability of the method of NTR.
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  • Masahiro Shiroishi, Miki Wadati
    Subject area: Mathematical methods in physics.
    1995 Volume 64 Issue 8 Pages 2795-2816
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    The decorated star-triangle relation (DSTR) discussed byShastry is extended into the general free-fermion model. Using thetrigonometric limit of the DSTR, we construct a new solvable bilayervertex model. The relation between the DSTR and the tetrahedralZamolodchikov algebra is discussed.
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  • Taira Suzuki
    Subject area: Classical and quantum physics: mechanics and fields.
    1995 Volume 64 Issue 8 Pages 2817-2827
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    A new theory of dislocation motion through the Peierlsfield in metals is described. First, quantized vibrations of thelattice containing a dislocation have been considered. Then, thequantum theory of resonance-type transfer of dislocations has beenworked out for two cases; electrons have no effect on the transfer inone case, and the nonadiabatic interaction of electrons withdislocations decreases the probability of the transfer in theother. Quantitative agreements have been obtained between theory andexperiment on the dislocation velocity vs. applied shear stress, theyield stress vs. temperature in copper, and the anomalous yield stressat low temperatures below 50 K of Cu--Al dilute alloys. The presenttheory applied to the loss of the strength of superconducting metalshas succeeded in explaining the experimentally observed temperaturedependence of this phenomenon in lead.
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  • Toshiya Iwai
    Subject area: Statistical physics and thermodynamics.
    1995 Volume 64 Issue 8 Pages 2828-2836
    Published: August 01, 1995
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    Dynamics of a kink in the presence of a quenched impurityis investigated both analytically and numerically by making use of thetime dependent Ginzburg-Landau equation for the case of a scalar orderparameter in a one-dimensional system without the thermal noise. Wefind the following results in our model. (i) The interaction betweenthe kink and the impurity is attractive. (ii) When the distancebetween the kink and the impurity is larger than the width of thekink, the motion of the kink is described by the logarithmic functionof time. This is similar to the growth law of dynamics of kinks andanti-kinks [K. Kawasaki and T. Ohta: Physica 116A (1982) 573.]. (iii)When the distance between the kink and the impurity is small, thedistance decreases exponentially with time and finally the kink ispinned by the impurity. (iv) When the distance between the kink andthe impurity is large, the order parameter field has the spiky defectat the impurity position.
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  • Ryutaro Sato
    Subject area: Statistical physics and thermodynamics.
    1995 Volume 64 Issue 8 Pages 2837-2847
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    We study the S matrix of a spin-{s} quantum spin chain whichcan be interpreted as a multicomponent quantum lattice gas. We showthat this system contains integrable subsystems where the Bethe ansatzmethod is applicable. We demonstrate that for some ranges ofparameters of a spin-1 model, the ground states and low-lying excitedstates are exactly given by those of integrable subsystems; exactcalculation is possible even if the system is not strictly integrableas a whole. We also analyze the magnetization curves for the spinchain, with exact saturation fields.
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  • Taro Ito, Noboru Shimomura, Tsutomu Yabuzaki
    Subject area: Atomic spectra and interactions of atoms with photons.
    1995 Volume 64 Issue 8 Pages 2848-2853
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    The transfer of nutating spin polarizations between 85Rb and133Cs atoms is observed for the first time. Maximum transfer occurswhen the nutation frequencies are made equal in the rotatingframes. The nutating spin polarization of 85Rb atoms is generatedby the periodic excitation of the pumping light and the spinpolarization transferred to 133Cs is observed through the Faradayrotation of a probe beam. The observed time evolutions of the spinpolarizations are found to be in good agreement with the results oftheoretical calculations based on the Bloch type equation of motionincluding the effects of optical pumping and spin exchange collisions.
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  • Masayoshi Okamoto
    Subject area: Fluid dynamics.
    1995 Volume 64 Issue 8 Pages 2854-2867
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Homogeneous turbulent flow with no mean velocity in arotating frame is analyzed using a two-scale direct-interactionapproximation to investigate the system-rotation effecttheoretically. On this basis, the system-rotation effect on the energyspectrum is discussed, and a model equation for the energy dissipationrate subject to the combined effects of unstationarity and systemrotation is derived. The latter is tested using experimental anddirect-numerical-simulation results and is shown to be in goodagreement with them.
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  • Shinya Okuda, Takahumi Miyazaki, Retsuo Kawakami, Nobuaki Ikuta
    Subject area: Kinetic and transport theory of fluids; physical properties of gases.
    1995 Volume 64 Issue 8 Pages 2868-2885
    Published: August 01, 1995
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    Transport properties of ions in model gases attemperatures Tg of 50 and 300 [K] are analysed using extended FTImethod with the assumption of isotropic scattering in the center ofmass frame. Single potentials inversely proportional to the powers ofinternuclear separation r as A· r-n which gives the collisionfrequency proportional to the powers of relative speed as v(n-4)/n_rare assumed for n values above 4. Variation of reduced thermalmobilities K0th with Tg in a low range of reduced electric fieldE/N and the E/N dependence of transport properties in a high E/N rangeare mainly discussed in relation with the power values n.
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  • Tatuhiro Yogi
    Subject area: Structure of liquids and solids; crystallography.
    1995 Volume 64 Issue 8 Pages 2886-2897
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    The molecular-dynamic method was used to simulate anitrogen fluid of 256 rigid diatomic molecules interacting through adouble Lennard-Jones potential. Several equilibrium structures andtime-dependent properties are calculated by integration and orthogonaltransformation for various values of temperature and density for theliquid phase. The orthogonal transformation is successfully introducedto give no difficulty of divergence. The orientational distribution ofmolecular axes and the center of mass velocity auto-correlationfunction are also obtained and discussed. The present analysis revealsthat the velocity auto-correlation has an exponential behavior similarto that of Brownian motion described by Langevin's equation at hightemperatures. Angular auto-correlation functions are obtained wherethe correlation is damped with time. The angular distribution and thusthe orientation of molecular axis are obtained. The structure andproperties of a diatomic liquid such as liquid nitrogen are not shownto depend on the ratio of principal moments of inertia.
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  • Shunsuke Hirotsu, Ikuo Yamamoto, Atsushi Matsuo, Takaharu Okajima, Hid ...
    Subject area: Equations of state, phase equilibria, and phase transitions.
    1995 Volume 64 Issue 8 Pages 2898-2907
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Brillouin scattering spectra of poly-N-isopropylacrylamide(NIPA) gels swollen to equilibrium in water were measured as afunction of temperature both in the swollen and the shrunkenphases. This is the first Brillouin scattering experiment on a gelundergoing a volume phase transition. At the discontinuous volumephase transition occuring at 33.6°C, large changes wereobserved in both of the Brillouin shift and the spectral width. Fromthe measured spectra and the temperature-dependent refractive index ofthe gel, the hypersonic velocity and the attenuation were determinedas a function of temperature. The results are analyzed in terms of thenature of sound propagation in gels, structure of the shrunken phase, relaxation processes of the network and solvent, and a role played bywater molecules at the phase transition.
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  • Keiichiro Aizu
    Subject area: Equations of state, phase equilibria, and phase transitions.
    1995 Volume 64 Issue 8 Pages 2908-2912
    Published: August 01, 1995
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    The transition from an artificially undulated prototypicphase to a ferroic phase is investigated. The wavenumber and amplitudeof the prototype undulation are denoted by ĥ and Urespectively. For simplicity a single order parameter is assumed, denoted by Q. When U is very small, only one ferroic phase ispossible, which is undulated at wavenumber ĥ. This hasbeen found before. The present paper finds that an extra term occursin the averaged free energy function if and only if Q undulates(itself) at ĥ/2. This term includes U as a factor. Owingto it, a ferroic phase undulated at ĥ/2 can occur, unless U is very small. The prototypic phase on cooling changes to theformer or latter ferroic phase accordingly to whether U< or>Uc. What expresses Uc is determined. A late part of the papertakes into account 3ĥ/2 (an overtone) besidesĥ/2.
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  • J. M. Zhang, W. LU, S. C. Shen, Y. C. Xu, J. Pelzl
    Subject area: Equations of state, phase equilibria, and phase transitions.
    1995 Volume 64 Issue 8 Pages 2913-2922
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    For the first time, the lattice instabilities and thenatures of the lattice instabilities of ammonium hexahalometallatesare studied by calculations of quantum chemistry and compared with ourexperimental results. It is found that, the barrier height to thereorientation of the ammonium ion group is very sensitive to thestructural parameters of the crystals. There are two differenttendencies of the mechanism for the structural instabilities with achange of the structural parameters. It is revealed that there existsa strong connection between the motions of the ammonium ions and thenatures of the lattice instabilities of the crystals. A commonexistence of the trifurcated hydrogen bonds in the ammoniumhexahalometallate crystals is supposed.
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  • Takashi Hotta
    Subject area: Electron states in condensed matter.
    1995 Volume 64 Issue 8 Pages 2923-2930
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    The density of states (DOS) of the two-dimensional Hubbardmodel is calculated in second-order perturbation with respect to theon-site Coulomb interaction U. The direct analytic continuationformula is presented to calculate the self-energy on thereal-frequency axis. The momentum as well as the energy integral inthe self-energy is seriously carried out with use of theFast-Fourier-Transformation algorithm. Near the half-filling, theimaginary part of the self-energy becomes proportional to the energyin the vicinity of the Fermi level in our weak-couplingcalculation. In the interacting case, the van Hove singularity (VHS)in DOS is smeared by the self-energy effect, but there still exists asharp peak structure due to VHS.
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  • Ken Deguchi, Tamifusa Matsuura, Yoshihiro Kuroda
    Subject area: Electron states in condensed matter.
    1995 Volume 64 Issue 8 Pages 2931-2953
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    We propose a model convenient for studying properties ofthe degenerate Anderson models including finite intra-atomic Coulombrepulsion U by using the perturbation expansion from the large limitof the spin-orbital degeneracy N (1/N-expansion). This is to extend aseries of 1/N-expansion studies on the U-infinite degenerate impurityand lattice Anderson models carried out by Nagoya group for includingeffects of finite U. As a first step, we study a case with a singleAnderson impurity to investigate crossover behavior between magneticstate and non-magnetic state as a function of U by calculating averagenumber of the localized electron, specific heat, charge susceptibilityand spin susceptibility in the leading order of (1/N) and also theKondo temperature and scattering rate of the conduction electrons upto the next leading order of (1/N).
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  • Masatoshi Imada
    Subject area: Electron states in condensed matter.
    1995 Volume 64 Issue 8 Pages 2954-2969
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Transitions between the Mott insulator and metals in cleansystems are analyzed with the scaling theory in terms of quantumcritical phenomena. In the case of generic transitions controlled bythe filling, the scaling theory is established from analyses of theDrude weight and the compressibility based on hyperscaling. In thetransition to the Mott insulator, a new universality class with thecorrelation length exponent ν <1/2 and the dynamical exponent z>2 isderived, which is in contrast to the transition to the band insulatorcharacterized by ν =1/2 and z=2. The unusual exponents lead tovarious anomalous characters of metals near the Mott insulator such asstrong suppression of the degeneracy temperature, and nonlineardependence of the Drude weight on the doping concentration. Remarkableproperties are also found in the specific heat, the compressibilityand spin correlations. A mechanism of high temperaturesuperconductivity is discussed in terms of the release from thesuppressed coherence.
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  • Kenji Ishida, Yoshio Kitaoka, Hiromi Masuda, Kunisuke Asayama, Toshihi ...
    Subject area: Electron states in condensed matter.
    1995 Volume 64 Issue 8 Pages 2970-2979
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Cu-NMR measurement was made to investigate the electronicproperty of the counterion site in (DMe-DCNQI)2Cu and(DMeO-DCNQI)2Cu where the metallic state is stabilized down tolow-T, (DBr-DCNQI)2Cu which exhibits the Metal-Insulator (M-I)transition and partially deutrated (DMe-DCNQI-d2[1, 1;0])2Cuwhich experiences a re-entrant (M-I-M) transition. In the metallicstate, the nuclear-spin-lattice relaxation rate, 63(1/T1) isfound to follow nearly T1T=const. law for all compounds except for(DMe-DCNQI)2Cu where (T1T)-1 is T-dependent above 100 Kbeing scaled to the square of the d-spin part of the Knight shift, K3d(T)2. From the analyses of 63(1/T1), it is shownmicroscopically that the metallic state is usual, unaffected by thecorrelation effect among d-electrons. At the M-I transition, the valueof 63(T1T)-1 and the Knight shift both being T-independentchange discontinuously without any clear enhancement in the metallicregion. The Cu-NMR results suggest that the d-electron correlationeffect does not play a primary role for the M-I transition.
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  • Naoyuki Shino, Shigemasa Suga, Shin Imada, Yuji Saitoh, Hajime Yamada, ...
    Subject area: Electron states in condensed matter.
    1995 Volume 64 Issue 8 Pages 2980-2987
    Published: August 01, 1995
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    Electronic structures of rare-earth hexaborides (RB6)have been investigated by photoemission and inverse photoemissionspectroscopy. The X-ray photoemission (XPS) features of the 3d and 4dcore states of heavy R elements are interpreted in comparison with themultiplet calculation. The valence band spectra probed by XPS andX-ray bremsstrahlung isochromat spectroscopy (X-BIS) methods are fullyutilized to interpret the optical conductivity spectra.
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  • Igor P. Zvyagin, Wataru Kinase
    Subject area: Electronic transport in condensed matter.
    1995 Volume 64 Issue 8 Pages 2988-2993
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    The temperature and composition dependence of thebarrier-controlled conductivity of two-phase composites is analysedreducing the problem to that of the site-bond percolation. It is shownthat the critical barrier height depends on the volume fraction φof the conducting phase, this giving rise to a specific φ-dependence of the activation energy of the conductivity near thepercolation threshold. Approximate relations suggested for the phaseboundary function of the site-bond problem make it possible toevaluate the distribution of inter-grain barrier characteristics fromthe measurements of the temperature and composition dependence of theconductivity near the percolation threshold.
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  • Norihisa Ishida, Tatsumi Kurosawa
    Subject area: Electronic transport in condensed matter.
    1995 Volume 64 Issue 8 Pages 2994-3006
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Hot carrier dynamics under intense microwave fields isinvestigated theoretically for the case that the dominant scatteringprocess is optical phonon emission. When the microwave amplitude isappropriately large, an accumulated distribution of carriers inmomentum space appears. This distribution is a new type of dynamicpopulation inversion and is found to cause various peculiar dc fieldresponses, e.g. strong nonlinearity, negative differentialconductivity, and often negative response, under realistic physicalconditions.
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  • Yuzo Shinozuka, Noriyoshi Ishida
    Subject area: Electronic structure and electrical properties of surfaces, interfaces and thin films.
    1995 Volume 64 Issue 8 Pages 3007-3017
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Self-trapping of an exciton interacting with the latticevia a short-range interaction is theoretically studied in two types ofquasi-low dimensional systems: anisotropic materials and quantum wellstructures. With a trial exciton wavefunction we variationallycalculate the minimum energy of the system. The results are comparedto those predicted in exact two- and one-dimensional systems. Inanisotropic systems the transition between the free (F) state and theself-trapped (S) state is a sudden change when the coupling constant gexceeds a certain critical value gc, being qualitatively the sameas in three-dimensional isotropic systems. As the anisotropyincreases, however, the height of the potential barrier separating Fand S decreases, and in the one-dimensional limit gc decreases tozero. In quantum well structures, as the width of a slab or a wirebecomes small, the character of the F-S transition gradually changesinto those in two-dimension or one-dimension respectively. Inwire-type quantum wells, a large-radius localized state characteristicof a one-dimensional system appears and coexists with the normalsmall-radius S state characteristic of a three-dimensional system.
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  • Hiroshi Ito
    Subject area: Superconductivity.
    1995 Volume 64 Issue 8 Pages 3018-3030
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    The responses to ac magnetic field for two-dimensional(2D) organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br, under dc magnetic field applied perpendicular to the 2D plane, aredifferent with respect to the frequency and orientation of the acfield. In the case of ac field applied perpendicular to the 2D plane, the frequency dependence is explained by the electromagnetic screeningtaking account of fluxoid dynamics and normal skin depth effects. Forthe ac field applied parallel to the 2D plane, the observedanisotropic behaviors are influenced by the effect of the interlayerdecoupling of pancake fluxoids.
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  • Hiroki Goto, Yuhei Natsume
    Subject area: Superconductivity.
    1995 Volume 64 Issue 8 Pages 3031-3037
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Beyond Migdal's theorem, the theoretical study on thestrong coupling superconductivity under the quantizing magnetic fieldin the system of isotropic 3-dimensional electron gas is reported. Thevertex correction is taken into account to the formulation, previouslydeveloped by the present authors in the expression of Dyson-Eliashbergtheory, which appears in J. Phys. Soc. Jpn. 63 (1994) 1465. Under thecondition that Ward-Takahashi identity is exactly satisfied, the setof equations including the vertex correction up to infinite order isproposed in the context of the theoretical investigation by Nambu inPhys. Rev. 117 (1960) 648. Numerical results for demanded strength ofthe field H for the given concentration of the electron density N arepresented in relation with the investigation of the problem of how theNambu-Goldstone mode appears. The possibility of new superconductingphase under the ultra-high field is also discussed.
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  • Hiroko Aruga katori, Yoshitami Ajiro, Takayuki Asano, Tsuneaki Goto
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 8 Pages 3038-3042
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    The magnetization process of a quasi-one-dimensionaltriangular-lattice antiferromagnet CsNiCl3 has been investigated upto 110 T using a single-turn coil technique. The magnetizationincreases with upturned curvature and reaches a saturation value of2.15μ B/Ni2+ around 73.5 T. From the saturation value andfield, the {g}-value and the intrachain interaction J/kB aredetermined as g=2.15 and J/kB=-13.2 K by assuming that theinterchain interaction is negligible. The magnetization for 1.5 Kobserved in low fields can quantitatively be explained by thespin-wave theory with the 1/S correction at zero temperature. Themagnetization for 5 K in high fields coincides with the result of thequantum Monte Carlo simulation at finite temperature for theHeisenberg antiferromagnetic chain of S=1. This means that the quantumfluctuations in the three-dimensional ordered state dominate themagnetization process in low fields, whereas the characteristics ofthe Heisenberg antiferromagnetic chain do in high fields.
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  • Keita Kishigi, Masahiro Nakano, Kazushige Machida, Yoshiki Hori
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 8 Pages 3043-3059
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    The effect of the magnetic breakdown on the dHvAoscillation is studied by full-quantum numerical calculation for atwo-dimensional model. We demonstrate that the interference differenceoscillation, usually designated as β -α, exists even in thethermodynamic quantity; this result is contrary to the conventionalsemi-classical picture. In addition, the dependencies of variousoscillations of the magnetization on the field, temperature and bandgap are examined thoroughly and compared with the semi-classicaltheory by Falicov and Stachoviak, which is based on the Pippard'scoupled network model and the Lifshitz-Kosevich formula. We discussthe relevance of our calculation to the observed interferencedifference frequencies in the dHvA oscillation of magnesium and in theSdH oscillation of two-dimensional organic conductors.
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  • Akio Sohma, Haruo Okajima, Tetsuya Yokoo, Atsushi Yamashita, Jun Akimi ...
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 8 Pages 3060-3065
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    The zero-field and the longitudinal field spin-relaxationsof positive muon (μ +) were measured in Cu1-xZnxGeO3(x=0, 0.01, 0.03, and 0.07) to study the spin-Peierls system. Theobtained relaxation functions were separated into two components belowTSP in CuGeO3. We conclude that the fast relaxation isoriginated from a few Cu2+ spins being not coupled withspin-singlet state, and that the slow relaxation is due to the nucleardipolar fields. The fast relaxation function shape changes to theGaussian at 5 K in the sample of x=0.07. The system changes from thestatic diluted to the densed one. We also confirmed the appearances ofthe spin-glass-like relaxations at 5 K in the samples of x=0.03 and0.07.
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  • S. T. Bramwell, P. C. W. Holdsworth, M. T. Hutchings
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 8 Pages 3066-3071
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    The layered XY ferromagnet Rb2CrCl4 has been studiedexperimentally for a number of years with the aim of establishing towhat extent the characteristic properties of the 2D-XY model, inparticular the Kosterlitz-Thouless-Berezinskii (KTB) phase transition, survive in a system with weak interlayer exchange coupling. We are nowable to give a definitive answer to this question, following a deeperunderstanding of the properties of the 2D-XY model. Simple lengthscale arguments and spin wave calculations suggest that the layeredmagnet is equivalent to an ideal 2D-XY system of an effective finitesize determined by the interlayer exchange. We show that thishypothesis, when combined with a recent renormalisation group approachto the finite size 2D-XY model, is sufficient to completely explainthe results of diverse neutron scattering and other experiments onRb2CrCl4. Our conclusion is that, except in a narrow 3D criticalregion, Rb2CrCl4 behaves as a finite 2D-XY system, with abroadened KTB transition occuring in the presence of three-dimensionallong range order.
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  • Yutaka Itoh, Akihiko Hayashi, Yutaka Ueda
    Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1995 Volume 64 Issue 8 Pages 3072-3081
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    We report the temperature(T)-dependent anisotropy r(≡63Wab/63Wcc) of the planar 63Cu nuclear spin-latticerelaxation rates 63Wα (α =ab, cc) in the high-TcCu oxides, YBa2Cu4O8, YBa2Cu3O6.96 andTl2Ba2CuO6+δ , from around Tc up to about 300 K. Wediscuss within the spin-fluctuation model that the anisotropy r isdependent only on the antiferromagnetic correlation length ξ andthat its T-dependence for the lightly-doped material is different fromthat of the over-doped ones. We provide the T-dependent anisotropy ras direct evidence of the T-dependent ξ .
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  • Norimichi Kojima, Hiroaki Okada, Morihiro Kawarazaki, Iwao Mogi, Masay ...
    Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
    1995 Volume 64 Issue 8 Pages 3082-3089
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Optical absorption spectra corresponding to the2F7/22F5/2 transition of Yb3+ in YbCrO3were investigated under high magnetic fields. The energy positions ofthese spectra remarkably changed at the metamagnetic transition wherethe weak ferromagnetic moment of the Cr3+ spins reverses itsdirection. From the analysis of the spectral change at the transition, the microscopic mechanism of the metamagnetic transition wereelucidated. In the energy region of the 2F7/22F5/2 transition of Yb3+, besides single-ion excitations, cooperative absorption spectra corresponding to the Yb3+ excitoncoupled with Cr3+ magnon and the Yb3+ exciton coupled withYb3+ spin-flip were observed. From the analysis of thesecooperative absorption spectra, the behavior of the Cr3+ magnonmode and the Yb3+ spin-flip mode under high magnetic fields wasinvestigated.
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  • Norimichi Kojima, Morihiro Kawarazaki, HiroakiOkada HiroakiOkada, Iwao ...
    Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
    1995 Volume 64 Issue 8 Pages 3090-3096
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    In YbCrO3, we have observed Cr3+--Yb3+two-exciton absorption spectra (A-E bands) corresponding to the4A22E, 2T1 transition of Cr3+ and the2F7/22F5/2 transition of Yb3+. Under highmagnetic fields, we have found that a bound state appears on thelowest energy side of the A band and has a strong dependence onexternal magnetic fields.
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  • Minoru Itoh
    Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
    1995 Volume 64 Issue 8 Pages 3097-3104
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    It is found that the Ex luminescence at 3.01 eV is absentin KI crystals grown from aqueous solution. This indicates that the Exluminescence is extrinsic feature of KI and arises from the radiativeannihilation of excitons localized near lattice imperfections. TheNa+-related luminescence at 2.60 eV in RbI is also confirmed to beabsent if the crystals are prepared from solution. The present workopens a way to study the self-trapping of excitons in KI and RbIwithout being disturbed by the influence of imperfection-relatedluminescence.
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  • Kenji Miyakawa, Tatsuya Noyori, Tadao Okabe, Michiko Mizoguchi
    Subject area: Physical chemistry.
    1995 Volume 64 Issue 8 Pages 3105-3111
    Published: August 01, 1995
    Released on J-STAGE: October 01, 1999
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    Effects of illumination on the ferroin-catalyzedBelousov-Zhabotinskii reaction system were studied by using a visiblelight. The bulk chemical oscillation became slower in the illuminatedarea. Consequently, various chemical waves were initiated at theboundary between illuminated and non-illuminated areas. Suchlight-induced phenomena are similar to those observed in thetris(2, 2'-bipyridine)ruthenium (II)-catalyzed system which is atypical light-sensitive photochemical one. Their behaviors stronglydepended on the illumination time given on the basis of the period ofoscillation in the non-illuminated area: in the case of illuminationduring one period, the change in contrast of the projected imageoccurred periodically. Under illumination during more than twoperiods, the contour of the projected image was formed at theboundary, and propagated to shrink towards the center of the projectedimage.
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