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Hiroshi Takano, Ayao Okiji
1981 年 50 巻 12 号 p.
3835-3836
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
The explanation of the phase diagram of the mixed compounds NiS
2−xSe
x is given with the use of the doubly degenerate Hubbard model. The metal-nonmetal transition in the antiferromagnetic phase can be explained by introducing the intra-atomic exchange interaction.
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Michio Midorikawa, Yoshihiro Ishibashi
1981 年 50 巻 12 号 p.
3837-3838
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
A small but distinct jump in thermal dilatation of a superionic conductor RbAg
4I
5 crystal was found at the cubic-trigonal transition temperature
T1=208 K, in addition to a large discontinuity at
T2=122 K. The jump observed at
T1 provides a direct evidence that the transition is of the first order as is expected from the Landau condition.
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Shinji Kawaji, Jun’ichi Wakabayashi, Jiro Moriyama
1981 年 50 巻 12 号 p.
3839-3840
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
T (temperature)- and
Ns (electron concentration)-dependence of the Hall conductivity in (0↓+) Landau level of n-channel (001) Si MOS inversion layers at 1.5 K∼12 K in 15 T is analysed based on a mobility edge model. Observations at
T≤2.5 K are reproduced by taking into account
Ns-dependence of the Landau level width. A possible way to account for observations at
T>2.5 K is to take into account
T-dependence of the mobility edge.
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Yasunori Tominaga, Hisako Urabe
1981 年 50 巻 12 号 p.
3841-3842
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
The temperature dependence of the low-lying pure longitudinal optical phonon mode of B
2(
z) symmetry in KDP has been observed by the backward Raman scattering. These B
2(LO) spectra have the under-damped phonon peaks at about 110 cm
−1, which are almost temperature independent. This result strongly suggests that the low-lying broad response of
y(
xy)
x Raman spectrum below ∼110 cm
−1 is primarily the transverse optical phonon excitation.
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Sukeomi Ogi, Yukio Watanabe, Nobuhiko Fujiwara, Masanori Akazaki
1981 年 50 巻 12 号 p.
3843-3844
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
An anomalous swelling of a local magnetic field was observed near the tube axis in the last stage of the implosion phase in a linear theta pinch with no bias field. This characteristic seems not to be explained by the radial plasma oscillation, but the effect of inelastic electron-neutral collision has a possibility of causing the large swelling.
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Toshio Okada, Keishiro Niu
1981 年 50 巻 12 号 p.
3845-3846
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
Filamentation and two-stream instabilities for a light ion beam (LIB) fusion system are investigated. Stability conditions for these two types of instabilities are derived for propagation through a background plasma. The results are illustrated by plotting stability boundaries for a proton beam propagating in a plasma.
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Kazuo Imasaki, Shuji Miyamoto, Tetsu Ozaki, Hisanori Fujita, Sadao Nak ...
1981 年 50 巻 12 号 p.
3847-3848
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
Uniform, long and stable plasma channels for the light ion beam transport were formed by the guidance of CO
2 laser. The typical required laser energy and applied electric field were 2 mJ/cm
−3·mbar and 10 V/cm·mbar, respectively.
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Junichi Kanzaki, Shigeru Odaka, Katsushi Arisaka, Sachio Komamiya, Mas ...
1981 年 50 巻 12 号 p.
3849-3858
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
Inclusive productions of π
0 and η
0 were measured at around 90° in the
p-nucleon center of mass system of 12 GeV
p-Be collisions. The invariant cross-section
Ed
3σ⁄d
3p was given as a function of
pt for the two processes.
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D. P. Goyal, A. Mozumder, P. K. Sengupta, S. Singh
1981 年 50 巻 12 号 p.
3859-3861
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
The distributions of rapidity intervals for pN interactions at 400 GeV have been studied. The study shows that the general features of cluster production do not change significantly as one goes from an energy 200 GeV to 400 GeV. The data further indicate that the threshold energy for the production of clusters heavier than resonances, is around 400 GeV.
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Shoji Hirata, Ichiro Matsuzaki, Akihiro Yanagita, Toshiharu Tako
1981 年 50 巻 12 号 p.
3862-3868
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
Successive transitions in an AC electric field in cholesteric liquid crystals with negative dielectric anisotropy have been investigated systematically. According to the relations between the frequency of applied AC field and the threshold voltage
Vth of successive transitions and between
Vth and cell thickness divided by cholesteric pitch
D⁄
P0 several features are observed. The threshold voltage for the dielectric regime extends to a DC electric regime. Quenching of the conduction regime is observed in a thinner sample cell. Some curious behaviors of the domain corresponding to the dielectric regime are also observed. A new model which can explain the mechanism of successive transitions in conduction regime is proposed.
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Kazuo Hida
1981 年 50 巻 12 号 p.
3869-3875
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
A simple lattice model of liquid crystals exhibiting a reentrant nematic-smectic A transition is presented. The qualitative features of the observed transitions are reproduced. A possibility of the direct transition from the low density nematic phase to the high density nematic phase is predicted.
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Nobuo Wada, Yoshio Kashima, Taiichiro Haseda, Bruno Morosin
1981 年 50 巻 12 号 p.
3876-3881
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
Two kinds of field-induced spin ordered states (labeled as A and B) in β-Ni (NO
3)
2·4H
2O are studied by measuring the temperature dependence of the specific heats and susceptibilities. The results reveal that the two ordered states behave like the two-dimensional square Ising system. The residual entropies below
Tc, 2
Sc⁄
R, measured under the appropriate magnetic field are 0.47×ln 2 under the field
H⁄⁄
zA and |
H|=27.6 kOe and 0.42×ln 2 under the field
H⁄⁄
zB and |
H|=43.7 kOe, where
zA(
zB) is one of the principal axes of rhombic crystal field
DSz2+
E(
Sx2−
Sy2) for the Ni
2+ ions associated with the A(B)-ordered state. The smaller value for
H⁄⁄
zB suggests the slightly larger anisotropy of the interactions along the rows and lines in the square lattice for the B-ordered state. The crystal structure of β-Ni(NO
3)
2·4H
2O determined recently is consistent with the above properties.
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Tetsuhiko Okamoto, Hironobu Fujii, Tadamiki Hihara, Kohji Eguchi, Tsun ...
1981 年 50 巻 12 号 p.
3882-3887
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
Measurements of the magnetization, magnetic susceptibility and NMR have been made for (Co
1−xMn
x)
2P single crystal compounds. The compounds with orthorhombic structure are ferromagnetic for 0.06<
x<0.63, ferromagnetic at high temperatures and screw antiferromagnetic at low temperatures for 0.63≤
x≤0.73 and antiferromagnetic for 0.73≤
x≤0.80. The magnetic moments of Mn
I and Mn
II are expected to have about 1 and 3 μ
B, respectively, from the measurement of NMR. The magnetocrystalline anisotropy constants
K1 and
K2 are both negative and their absolute values take maxima at
x=0.5. The Curie temperatures and saturation magnetic moments for
x≤0.5 compounds are briefly discussed with the exchange interaction and the local environment of Mn
II site.
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Mitsuo Kataoka, Osamu Nakanishi
1981 年 50 巻 12 号 p.
3888-3896
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
For the spin systems with both the symmetric exchange interaction (SEI) and the antisymmetric exchange interaction (AEI) (the Dzyaloshinsky-Moriya interaction), the relative stability between the ferromagnetic state (FMS) and the helical spin density wave (HSDW) is discussed phenomenologically. The arguments are made to the spin systems of which the spin structures are described by the spin density
S(
r) varying slowly with the position
r and the SEI is favorable to the FMS. For the 21 types of crystal symmetry with the isogonal point groups having no inversion symmetry, the characteristics of the instability of the FMS are investigated. By use of the Landau free energy obtained for crystals with the isogonal point groups
T and
O, the magnetization process, the magnetic phase diagram, and the intensity of the neutron diffuse scattering are calculated. A comparison between the calculated results and the experiments on MnSi is also given.
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Yoshiko Someya
1981 年 50 巻 12 号 p.
3897-3903
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
The phase diagram of a random mixture of two antiferromagnets with competing spin anisotropies (A
1−xB
x) has been analyzed by extending the theory of Matsubara and Inawashiro, and Oguchi and Ishikawa. In the model assumed, the anisotropy energies are expressed by the anisotropic exchange interactions. According to this formulation, it has been shown that the concentration dependence of
TN becomes a function of (
Remark: Graphics omitted.), where P, Q=A, B;
SP is a magnitude of P-spin, and
JPQη is a η component of exchange integral between P- and Q-spin). Further, the phase boundary between an AF phase and an OAF (oblique antiferromagnetic) phase at
T=0 K has been shown to be determined by α(≡
SB⁄
SA), if (
Remark: Graphics omitted.) are given. The obtained phase diagrams for Fe
1−xCo
xCl
2, K
2Mn
1−xFe
xF
4 and Fe
1−xCo
xCl
2·2H
2O are compared with the experimental ones.
抄録全体を表示
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Kimio Adachi
1981 年 50 巻 12 号 p.
3904-3910
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
Electron spin resonance was measured at 9.40 GHz as a function of temperature in a quasi-one-dimensional Ising-like antiferromagnet CsCoCl
3. Observed resonance in the partially disordered phase,
TN2\lesssim
T<
TN1 and its neighborhood is interpreted in terms of ESR due to spins at propagating domain walls in one-dimensional Ising-like antiferromagnet. The theory developed by Shiba and the present author gives a more consistent interpretation of the temperature dependence of the absorption intensity and the angular dependences of the resonance field and the linewidth than the existing theories. Discussion is given in connection with spin-cluster resonance.
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Norikatsu Yamada, Yoshitomo Karaki, Nobuo Wada, Kiichi Amaya
1981 年 50 巻 12 号 p.
3911-3918
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
The magnetic phase transition is studied by the AC susceptibility and the specific heat measurements in NaNi triacetylacetonate benzene which is considered as an example of an antiferromagnetic triangular Ising lattice. The magnetic phase transition from paramagnetic to ferrimagnetic state is observed at the temperature
Tc0≅32.5 (mK) by the AC susceptibility measurements. The
H vs
T phase diagram is obtained giving the extrapolated value of
Hc0≅320 (Oe) at
T=0 K. At
Tc0 the susceptibility does not diverge to infinity, and below
Tc0 it increases with decreasing temperature. This new type of behavior of the ferrimagnetic transition is qualitatively well described by the antiferromagnetic triangular Ising lattice model.
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Yûichi Tazuke, Hidekazu Tanaka, Katsunori Iio, Kazukiyo Nagata
1981 年 50 巻 12 号 p.
3919-3924
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
Susceptibilities of single crystals of CsCuCl
3 are measured in 4.2 K<
T<500 K for
H⊥
c and
H⁄⁄
c. Behaviors characteristic to a one-dimensional Heisenberg ferromagnet with weak interchain interactions are observed. The behaviors are analyzed by the high temperature expansion approximation, and intrachain and interchain exchange interaction constants,
J0 and
J1, are estimated. The results are,
J0⁄
k=(24±3) K and
J1⁄
J0=−0.16±0.04. A discontinuity in the susceptibility arising from a Jahn-Teller cooperative phase transition are observed at
Tt∼420 K. The discontinuity is due to a change in
J0 at
Tt. Relation between the phase transition and the change of
J0 is discussed.
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Yoshiaki Chiba, Taturu Yosida, Muneyuki Date
1981 年 50 巻 12 号 p.
3925-3931
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
Electron spin resonance of Co
2+ ion in yttrium aluminum garnet is investigated and three kinds of Co
2+ spin sites are found. Most of the Co
2+ ions occupy the octahedral site with
g⁄⁄=6.470 and
g⊥=3.050 and the tetrahedral site spins with
g⁄⁄=2.446 and
g⊥=2.176 are also found. Other complex spectra are attributed to the interstitial Co
2+ spin respnance with
gx=1.94,
gy=3.80 and
gz=5.57. There are 24 magnetically-inequivalent interstitial sites and the observed lines are satisfactorily assigned by this model.
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Hikaru Terauchi, Kiyoshi Sakaue, Moritaka Hida
1981 年 50 巻 12 号 p.
3932-3936
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
The X-ray diffraction profiles of the ω-phase in Ti
1−xMo
x, 0.07≤
x≤0.20, are carefully examined for the first time. The intensity distribution near the wave vector
q0=(2⁄3, 2⁄3, 2⁄3) is asymmetric. The ω-phase appears in rod shaped clusters along the 〈111〉 direction in the body-centered-cubic lattice. The incommensurate diffuse scattering can be detected above the critical composition
xc=0.10. The scattering profiles are almost independent of temperature over a temperature range −120°C to 50°C. The observed diffuse scattering is discussed in terms of the planar displacements described by a stacking soliton and the coherency of the ω-phase domains.
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Masahiro Matsumura, Naokatsu Sano, Tadashi Taniguchi, Kunisuke Asayama
1981 年 50 巻 12 号 p.
3937-3943
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
Knight shift, K, nuclear spin-lattice relaxation time, T
1, and spin echo decay time, T
2, at various sites have been measured for SnMo
6Se
8, PbMo
6Se
8 and PbMo
6S
8. K shows little change in the superconducting state from the value of normal state, which implies the remaining of the spin susceptibility of conduction electrons in the superconducting state. The density of state at the Fermi level is evaluated from T
1 in the normal state. The agreement of the results with the recent band calculation is satisfactory except for Se site, where the experimental result suggests larger density of state. The superconducting energy gaps are about 3.5
kBT
C(0) for all sites. Not only
d-electrons of Mo but
s- or
p-electrons of Sn, Pb and Se atoms take part in the superconductivity. T
2 for all sites decreases with the onset of the superconductivity. This may be attributed to the conversion of the indirect coupling between
like spins to the
unlike ones effectively owing to the field inhomogeneity due to vortices.
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Jiro Yamashita
1981 年 50 巻 12 号 p.
3944-3951
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
Two kinds of the potential are used for the APW calculation of metallic lithium. The one is the Seitz potential and the other is the Xα-potential. The shape and the size of the Fermi surface, the Fermi velocity, the wave functions and the matrix elements of the electron-phonon interaction are calculated by APW. By using these data and the empirical force constants in the Born-von Karman model, we have carried out the first principle calculation of the temperature dependence of the electrical resistivity, the Hall coefficient, the thermoelectric power at the normal volume and the volume dependence of the resistivity. The theoretical results are in good agreement with experimental values.
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Ven-Chung Lee, How-Sen Wong
1981 年 50 巻 12 号 p.
3952-3955
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
The electronic structure of the ZnS(110) surface is studied by the LCAO method. We have studied the surface band structure over the surface Brillouin zone in some detail.
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Toshihisa Yamaguchi, Katsumi Hamano
1981 年 50 巻 12 号 p.
3956-3963
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
The complex piezoelectric constants,
d21,
d22 and
d23, of ferroelectric AgNa(NO
2)
2 have been measured by two quasi-static methods; one is the optical interferometric method and the other is based on a comparison with the piezoelectric constant of quartz. The measurement covered the temperature range from 40°C to −80°C and the frequency range from 5 Hz to 50 kHz. All
d2j’s show dispersion of the Debye type,
d2j(ω)=
d2j(∞)+[
d2j(0)−
d2j(∞)]⁄(1+
iωτ). The relaxation time, τ, which is of the order of 5×10
−6 sec at room temperature coincides with the dielectric relaxation time and shows critical slowing down toward
Tc (37°C). It has been found that the dipolar contribution, [
d2j(0)−
d2j(∞)], and the ionic and electronic contribution,
d2j(∞), are of opposite signs to one another and the static piezoelectric constant,
d2j(0), changes its sign at some temperature in the ferroelectric phase.
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Yukikuni Akishige, Tutomu Kubota, Kikuo Ohi
1981 年 50 巻 12 号 p.
3964-3971
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
The electron spin resonance of Fe
3+ ion in Sr
2Nb
2O
7 single crystal has been studied in the ferroelectric normal phase. The main ESR line is associated with |±1⁄2〉 transition of Fe
3+ ion in one of two distorted NbO
6 octahedra. The angular dependence of the ESR line can be fitted with the crystal field parameters obtained from the third-order perturbation: |
D|=0.50 cm
−1 and |
E|=2.36×10
−2 cm
−1. The calculation based on the superposition model shows that the sign of
D is positive and Fe
3+ ion sites on near the center of the octahedron rather than the position of Nb ion.
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Masaru Kasahara, Itaru Tatsuzaki
1981 年 50 巻 12 号 p.
3972-3976
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
Light scattering spectra of mixed crystals KDP
1−xDKDP
x with
x=0.08, 0.04 and 0.0 (KDP) are measured by a Fabry-Perot interferometer with a free spectral range of 8 cm
−1. Spectra are analyzed with the Debye type susceptibility of a polarization fluctuation coupled to an acoustic phonon. The relaxation times of an isolated dipole for
x=0.08, 0.04 and 0.0 are found to be 0.27, 0.21 and 0.15 in the unit of 10
−12 sec, respectively.
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Hikaru Terauchi, Kazuhiro Tanabe, Hironobu Maeda, Moritaka Hida, Nagao ...
1981 年 50 巻 12 号 p.
3977-3979
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
The Fourier transform of EXAFS curve of PbTiO
3 in an amorphous state has been determined. That of crystalline state has also been obtained and the effect of annealing the amorphous specimen has been studied.
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Kazutaka Sato, Akira Sugiyama
1981 年 50 巻 12 号 p.
3980-3987
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
A dislocation in a material of high Peierls barrier moves in a direction of an external force by successive formation of a new pair of kinks and by propagation and annihilation of the kinks. Dislocation velocity depends on a formation rate and on a propagation velocity of the kinks. A computer simulation gives that the moving dislocation is not a straight line but is distributed over many Peierls valleys containing many kinks. It also gives that, 1) an average dislocation velocity is approximately proportional to the geometric mean of the formation rate and the propagation velocity, and 2) the distribution of dislocation segments is not truly stationary but quasi-stationary within the time of a present computation. A new treatment of the average dislocation velocity reproduces results given by the computer simulation approximately.
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Kazuo Soda, Noriaki Itoh
1981 年 50 巻 12 号 p.
3988-3995
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
Measurements were made of the absorption change at the
F band and of the singlet luminescence in NaCl, induced by photoexcitation of the lowest state of the triplet self-trapped excitons into excited states higher than the lowest state by 1.7 eV∼2.8 eV. It is found that excitation with photons below 2.5 eV causes both the
F-center creation and the σ-luminescence, while excitation with photons above 2.5 eV causes only the σ-luminescence. These results indicate that non-radiative transition from the higher excited states to the lowest state of the self-trapped exciton is selective. The cause of the selectiveness is discussed. The yield of the
F center creation at the higher excited state of the self-trapped exciton was found to be about 10
−2. The stability of the created
F centers in NaCl is found to be lower than in other alkali chlorides.
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Hiromu Ueba, Shoji Ichimura
1981 年 50 巻 12 号 p.
3996-4005
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
Fano’s treatment for the interaction between a discrete level and a continuum state is used to calculate the eigenstates of molecules adsorbed on a metal surface, where both surface plasmon and electron-hole pair excitations due to the Coulomb field of the molecular dipole are taken into account. Spectral density of states of adsorbed molecules shows more broadened structure than that calculated by a simple image dipole model. The role of electron-hole excitations on the Raman scattering of adsorbed molecules is then investigated.
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Masataka Mizushima
1981 年 50 巻 12 号 p.
4006-4012
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
It is shown that Zener’s theory of adiabaticity is applicable to find the probability of photon absorption (or emission) by molecules. In contrast to the conventional approach based on Dirac’s time dependent perturbation theory, in which the broadening of spectral lines is of secondary importance, the present theory shows that spatial inhomogeneity produced by intermolecular potentials is vitally important in the radiation processes. Our results agree with the established parts of the conventional theories, but some new effects are also predicted.
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Hirohumi Sakashita, Nobuhiko Ohama, Atsushi Okazaki
1981 年 50 巻 12 号 p.
4013-4021
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
The lattice constant of KMnF
3 has been measured by means of the high-angle double-crystal X-ray diffractometry (HADOX). The relative accuracy of the lattice constant to one part in 10
6 is attained. The value of the critical exponent β for the static rotation angle of MnF
6 octahedra below the structural phase-transition temperature (186.65 K) is determined to be 0.2857±6 from the lattice constant
a(
T); the value is significantly smaller than 0.38 predicted for a 3D-Heisenberg system and even than 0.315 for a 3D-Ising system, with an isotropic short range interaction. This suggests that the transition occurs in the vicinity of a tricritical point. The lattice constants themselves also exhibit a critical behaviour; the value of the critical exponents are 2β for
a(
T) and β for
c(
T).
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Masanori Hidaka, Shigeru Yamashita, Kiyoshi Inoue, Noboru Tsukuda, B. ...
1981 年 50 巻 12 号 p.
4022-4029
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
The successive structural phase transitions of CsVF
4 have been studied by means of polarizing and electron microscopes. A new phase in the temperature range 240°C to 250°C has been found. It became clear that the transitions at 152°C, 240°C and 250°C have the character of the first ordering on account of the co-existence of two phases near the transitional point. Then, a notation of each phases is as follows: Phase I (≥250°C), II (240≤ ≤250°C), III (152≤ ≤240°C) and IV (≤152°C). From the results of electron diffraction, the satellite and the diffuse reflection, observed by electron diffraction, are interpreted in terms of an oscillation of the VF
6 octahedra about the principal axes of the idealized structure.
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Motoshi Uchiyama, Chikara Ishii
1981 年 50 巻 12 号 p.
4030-4034
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
A stable structure of cholesteric liquid crystal thin film in a magnetic field is explored under the boundary condition that the film is strongly anchored at one surface and kept free at the other. It is shown that the system shows a series of first order phase transitions. A step-wise change of helical pitch is obtained as a function of external magnetic field.
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Kazunari Ikuta
1981 年 50 巻 12 号 p.
4035-4038
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
Ablation acceleration of macroparticle along field lines in a spiral magnetic field is considered in detail in order to give the accelerated body a spin.
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Teruo Saito, Shin Kubo, Masahiko Nakamura, Yasuji Hamada, Shigetoshi T ...
1981 年 50 巻 12 号 p.
4039-4046
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
A submillimeter wave scattering method was used to study low frequency, small scale, density fluctuations in plasmas and we have observed a microturbulence in a range of drift waves in the WT-1 and 2 tokamaks. The density fluctuations are very intense (\ ilde
ne⁄\ ilde
ne∼several percent). The wavenumber spectra have a peak at
k⊥ρ
s\simeq0.5 and are isotropic in the two-dimensional
k⊥ plane, where
k⊥ is the wavenumber perpendicular to the toroidal field
BT and ρ
s=(MT
e)
1⁄2⁄e
BT. The frequency spectra are very broad and the high frequency components are contained in an inner part of the plasma. Further, their intensity decreases and the frequency spectrum becomes narrow when the lower hybrid wave driven current is generated.
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Katsunobu Nishihara, Masayoshi Tajiri
1981 年 50 巻 12 号 p.
4047-4053
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
This paper shows that rarefaction ion acoustic solitons appear in a two-electron-temperature plasma. And also it presents general conditions and physical mechanism for existence of the rarefaction solitons. It is found that finite amplitude rarefaction and compression solitons coexist in a plasma within a certain parameter region.
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Kyoji Yamamoto, Kenji Watanabe, Shinichiro Yanase
1981 年 50 巻 12 号 p.
4054-4062
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
The stability of a quadruple vortex street, i.e. a pair of double vortex streets in a perfect fluid is investigated for small disturbances. Permanent configurations are first determined; two of which are then examined in their stability—one is a symmetric arrangement of a pair of staggered (Kármán-type) double streets and the other is an antisymmetric arrangement of the pair.
The stability curves are obtained for several values of ratio of the distance 2
b0 between the double streets to the spacing
a between consecutive vorticies in a row. It is found that both types are neutrally stable for most of disturbances except unstable disturbances in very narrow ranges of a parameter specifying the disturbances mode, provided that
b0⁄
a\gtrsim0.5 and
b⁄
a is taken to be about 0.28, where
b is the breadth of the double street. The symmetric type is more stable than the antisymmetric one.
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Moon-Uhn Kim
1981 年 50 巻 12 号 p.
4063-4067
発行日: 1981/12/15
公開日: 2007/06/01
ジャーナル
認証あり
Steady symmetric rotation of a disk in an infinitely long circular cylinder is considered on the basis of the Stokes approximation. A series expression in powers of the disk-cylinder radius ratio is obtained for the torque necessary to maintain the rotation. As the ratio approaches to unity, the torque increases logarithmically and the estimate from the series expression is shown to agree well with that from an exact asymptotic theory.
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Hidenori Hasimoto
1981 年 50 巻 12 号 p.
4068-4070
発行日: 1981/12/15
公開日: 2007/05/29
ジャーナル
認証あり
The axially symmetric flow problem due to a stokeslet situated along the symmetry axis through a circular hole in a rigid plane wall is examined. Concise expression for the solution in terms of the Green function is obtained. The singularity in the solution of the basic equation presented by Davis
et al. (J. Fluid Mech.
103 (1981) 183) is pointed out and removed with a slight modification of their results.
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