-
S. Dasgupta, C. K. Majumdar
1982 Volume 51 Issue 12 Pages
3741-3742
Published: December 15, 1982
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A new method based on the computation of the zeros of the partition function is presented for calculating the phase boundary of an antiferromagnet in weak magnetic field. The results agree with those of Müller-Hartmann and Zittartz as well as the phenomenological scaling approach by Sneddon.
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Koki Takanashi, Hiroshi Yasuoka, Kenji Kawaguchi, Nobuyoshi Hosoito, T ...
1982 Volume 51 Issue 12 Pages
3743-3744
Published: December 15, 1982
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The
51V NMR signals have successfully been observed in a multilayered Fe–V film with artificial superstructure made by the ultra high vacuum deposition technique. The hyperfine field distributions near the interface obtained from the spin-echo NMR spectrum are in accord with the prediction of the magnetic moment distributions calculated recently.
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Kikuo Ohi, Hiroshi Omura, Takao Kazumi, Masaaki Takashige, Min-Su Jang ...
1982 Volume 51 Issue 12 Pages
3745-3746
Published: December 15, 1982
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Raman spectra of Sr
2Nb
2O
7 have been obtained between 45 K and 395 K. A low-lying mode observed at
a(
bc)\bar
a geometry softens toward the 117 K transition temperature and the square of the soft-mode frequency depends linearly on temperature on both sides of the phase transition. The soft mode remains underdamped in entire range of temperature studied.
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Koji Kajita
1982 Volume 51 Issue 12 Pages
3747-3748
Published: December 15, 1982
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Simultaneous measurement of the electron conductivity and the third sound velocity is made for a
two dimensional electron-helium film-solid neon system. The dependence of the electron conductivity on the helium film thickness is determined.
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Kensuke Hoshi, Gendo Oomi, Nobuo Mori
1982 Volume 51 Issue 12 Pages
3749-3750
Published: December 15, 1982
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The electrical resistivity of Fe
65(Ni
0.84Mn
0.16)
35 alloy is measured under high pressure up to 30 kbar from 4.2 K to 300 K. A resistance minimum is found near 25 K at atmospheric pressure. The temperature of the resistance minimum is appeared not to depend on pressure. Isothermal resistivity shows anomalous behaviors against pressure below 150 K. These results suggest the existence of a pressure induced magnetic phase transition at low temperature.
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Yasuhiro Kawamata, Keiji Yada
1982 Volume 51 Issue 12 Pages
3751-3752
Published: December 15, 1982
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It is observed that bromine bubbles are produced via a planar state by irradiation with 75 keV electrons at the confined temperatures around 100°C, when beam intensities are very low (0.5 mA/cm
2). However, the planar precursors of bubbles are not observed often as in KCl because of another dominant process of bubble formation. Many bubbles are formed inside interstitial-type dislocation loops beforehand produced. These bubbles have no observable precursor.
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Yukio Kazumata, Shigemi Yugo
1982 Volume 51 Issue 12 Pages
3753-3754
Published: December 15, 1982
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In pyro-graphite bombarded with high energy chlorine ions, two kinds of paramagnetic centers are observed by ESR. These centers are interpreted as conduction carriers in a sample containing a large amount of acceptors produced by the bombardment and localized spin centers in an amorphous state. It is proposed that the transition from conduction carriers to localized spin centers will be studied in detail by high energy ion bombardments.
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Hazime Matsuura, Tomio Matsuzaki, Yuji Fukazawa, Yoshihito Abe
1982 Volume 51 Issue 12 Pages
3755-3756
Published: December 15, 1982
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14N NQR lines in 1,2-diphenylhydrazine have been investigated between 4.2 K and 370 K by using a pulsed spectrometer. With increasing temperature, the number of resonance line in NQR spectra decreased from six lines to three lines above 115 K. The temperature dependence of resonance lines reveals that 1,2-diphenylhydrazine makes a second order structural phase transition around 115 K. An information about the molecular structure is also obtained.
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Osamu Sueoka
1982 Volume 51 Issue 12 Pages
3757-3758
Published: December 15, 1982
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The 2
1S-excitation cross-section
Qexc and the ionization cross-section
Qion of He atom by positron impact were obtained in the range of 24∼120 eV positron energies by the time spectrum in the retarding potential-TOF method. The excitation cross-section is consistent with those by Coleman and Hutton at the energies below 31 eV. The values of
Qion agreed with those by electron-collision measurements.
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Yoneyoshi Kitagawa, Aye Thein, Yoshiyuki Yamada, Masahiro Yokoyama, Ch ...
1982 Volume 51 Issue 12 Pages
3759-3760
Published: December 15, 1982
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CO
2-laser light irradiation on a dense plasma focus can enhance the neutron yield and the magnetohydrodynamic instability only at the threshold pressure region and for the timing from −100 ns to 300 ns around the peak compression. At the same time, the laser transmission is periodically reduced.
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Yukiya Hattori, Chikara Fukunaga, Ryosuke Hamatsu, Tachishige Hirose, ...
1982 Volume 51 Issue 12 Pages
3761-3765
Published: December 15, 1982
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We present Feynman- and Bjorken-variable distributions for the diffraction dissociation (
dd) π
±p→π
±(π
N)
dd at 6 and 16 GeV/c.
The Bjorken variable 〈
XB〉 averaged over a certain (π
N) mass interval slowly decreases as the (π
N) mass increases. The magnitude of 〈
XB〉 is considerably small, namely 〈
XB〉∼0.1 at
M(π
N)=1.5 GeV as compared with the value obtained in the lepton-hadron scattering. We found that the usual slope-mass correlation of dd was closely related with the mass dependence of the Bjorken variable.
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K. Singh, H. S. Sahota
1982 Volume 51 Issue 12 Pages
3766-3773
Published: December 15, 1982
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The decay of 67h
99Mo to the levels of
99Tc has been studied with Ge(Li), Ge and Si(Li) detectors. Some new gamma rays of energies of 38, 163.4, 319.8, 321.0, 352.9, 599.6, 727.07 and 1082.2 keV have been observed. One new level at 163.4 keV is suggested and two controversial levels at energies 726.7 and 1081.4 keV have been confirmed. The directional correlation system has been used to measure the 740–181, 740–(40)–140, 961–181 and 822–(40)–140 keV cascades. These measurements confirm 3/2
+, 5/2
− and 1/2
− spin assignments for 921.0, 1004.2 and 1142.1 keV levels. The mixing ratios of 40.585, 140.511, 739.7, 823.1 and 961.0 keV gamma rays have been obtained as M1+
≤6.25×10
−2% E2, M1+9±1% E2, E2+8.0±1% M1, E1±1% M2 and M2+E2, respectively.
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Shigeki Hayashi, Shiro Iwata
1982 Volume 51 Issue 12 Pages
3774-3781
Published: December 15, 1982
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Angular distributions of recoil
8Li in the
9Be(π
−, π
N)
8Li reaction have been measured at
Pbeam(π
−)=1.0, 3.0, and 4.0 GeV/c with solid state track detector (SSTD). At 1.0 and 3.0 GeV/c, the heavy-fragment knockout process explains the major feature of the data, whereas at 4.0 GeV/c a characteristic sideways peaking is observed at around θ
1ab\simeq30°. The latter phenomenon shows that another effects must begin to occur at around 4.0 GeV/c. The
12C,
14N,
16O→
8Li,
8B spallation reactions by π
− mesons (background reactions) have also been measured. They are mainly due to the intra-nuclear cascade and evaporation process.
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Hiroshi Endo, Takashi Yamaya, Kentaro Umeda, Susumu Morita
1982 Volume 51 Issue 12 Pages
3782-3789
Published: December 15, 1982
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A low-lying 5/2
− (0.373 MeV) state and a 3/2
− (0.593 MeV) state in
43Ca, and a 5/2
− (0.176 MeV) state of
45Ca were studied by means of the (d, p) reaction above and below the Coulomb barrier. The angular distributions and the excitation functions were measured for these weakly excited states, and the obtained data together with the reported data at
Ed=7.0 and 10.0 MeV were analyzed using the second-order DWBA and the statistical compound model. For the 5/2
− and the 3/2
− states of
43Ca, the contribution from the direct process plays a significant role and gives evidence of the single particle component in the wave functions of these states, but this process can hardly be considered for the 5/2
− (0.176 MeV) state of
45Ca.
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Yasuo Igura
1982 Volume 51 Issue 12 Pages
3790-3801
Published: December 15, 1982
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A simplified method of mode coupling equation is applied to the critical dynamics near the lambda line of dilute solution of
3He in
4He. The order parameter, the
3He concentration, and the entropy are the relevant modes as discussed by Siggia and Nelson. Using the concept of the self-consistent self-energy, developed by Ferrell and Bhattacharjee for
4He, we obtain the characteristic frequencies of these modes, the fluctuation spectrum, and the damping constant. The self-consistent self-energies satisfy the dynamic scaling hypothesis and the exponent
z turns out to be
d⁄2, d being the dimension of the system. The
3He concentration dependence of the amplitudes of the self-energies is found to be very peculiar. The fluctuation spectrum is shown to depend on the amplitude ratios very much. It never takes the double humped form.
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Minoru Tanaka
1982 Volume 51 Issue 12 Pages
3802-3809
Published: December 15, 1982
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The molecular dynamics method is used to simulate the rapid-quenching process of a simple liquid metal. The model consists of 864 particles with the density-dependent effective pair potential, which can describe the structure of liquid rubidium above the melting point. The rapid-quenching process from just above the melting point of rubidium down to around 4.2 K is simulated by subtracting the kinetic energy of particles intermittently with the quenching rate of 4.5×10
12 Ks
−1. In the final quenched state at 4.5 K both the pair distribution function and the structure factor show a feature of amorphous states, that is, the split second peak. The relative positions and the ratio of the heights of these split subpeaks are very close to those of the quenched argon (the molecular dynamics simulation) and also of amorphous iron (the evaporated film), and the final quenched state can be considered as a typical model of amorphous pure metals.
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Yoshio Kuramoto, Rolf R. Gerhardts
1982 Volume 51 Issue 12 Pages
3810-3819
Published: December 15, 1982
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The ground state of a two-dimensional electron system in a strong magnetic field is studied in the Hartree-Fock approximation for the case of a half-filled ground Landau level. Due consideration is given to consequences of the electron-hole symmetry, which is found to lead to a nonmetallic CDW ground state. The Hartree-Fock integral equations are solved numerically with full account of higher harmonics. The result shows that the ground state is not a triangular CDW, in spite of the most favorable Madelung energy, but a square CDW with the electron-hole symmetry spontaneously broken. Detailed results for band structures, density patterns and cohesive energies are presented.
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Toshimitsu Musha, Katsumi Sugita
1982 Volume 51 Issue 12 Pages
3820-3825
Published: December 15, 1982
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Conductance fluctuations were observed in CuSO
4 aqueous ionic solutions over ion concentrations from 5×10
−4 to 10
−2 mol/l. It is found that the spectral density is approximately 1⁄
f for ion drift velocities smaller than a critical value which is of order of 10
−3 m/s; above this value it approaches a Lorentzian form. The α-value of the 1⁄
f fluctuation is approximately proportional to the ion concentration when it is larger than 10
−3 mol/l; below this critical value the α-value seems to take a constant value 2.5×10
−2. The existence of the critical ion concentration suggests that, if the 1⁄
f conductance fluctuations are caused by mobility fluctuations, the 1⁄
f conductance fluctuation has a coherence length, which is estimated to be 10 nm.
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Katsutoshi Aoki, Shuzo Fujiwara, Masao Kusakabe
1982 Volume 51 Issue 12 Pages
3826-3830
Published: December 15, 1982
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Powder X-ray diffraction experiments were made for Bi up to the maximum pressure of 40 GPa. The high pressure bcc phase was found to be stable for a wide range of pressure above 7.7 GPa. Energy differences of the structure-dependent part of cohesive energy between the fcc, hcp, bcc and sc phases are calculated as a function of volume using the model pseudopotential method. It is shown that the bcc phase is stable relative to the other phases at high pressure in agreement with the experimental results.
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L. Ch. Papaloucas, A. D. Jannussis
1982 Volume 51 Issue 12 Pages
3831-3843
Published: December 15, 1982
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In this paper nonlocal potentials of Hulthen and Gauss forms are investigated. Emphasis is placed on the limits −∞ to +∞, in which case the integral equations are transformed into equivalent Schrödinger equations in k-space. Also, for the case of finite limits we give the physical and the Jost solutions by the moment method as well as using the Green’s function.
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Susumu Kurihara
1982 Volume 51 Issue 12 Pages
3844-3849
Published: December 15, 1982
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A Fröhlich-type Hamiltonian is derived for third sound and
3He quasi particles in phase-separated double layer of superfluid
4He and normal
3He liquid. It is stressed that our system is unique and valuable in that characteristic parameters can be varied in a wide range, simply by adjusting the film thickness. The effect of fermion-boson coupling on the velocity and damping of the third sound is examined. It is predicted that a rather drastic change in the third sound spectrum will occur when the Fermi velocity of
3He system and the third sound velocity are nearly the same. It is pointed out that the system under consideration may show a variety of interesting phenomena, in addition to the softening of the third sound.
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Masao Kamiya, Kazuhiro Hara, Hiroshi Fujiwara
1982 Volume 51 Issue 12 Pages
3850-3852
Published: December 15, 1982
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The differences between optical constants for the directions perpendicular and parallel to the incidence plane,
Δn and
Δk were measured in iron films deposited at oblique incidence and their correspondences to the anisotropy field
Hk were investigated. The difference
Δn occasionally has the opposite sign to
Hk and its dependence on the film thickness is different from that of
Hk. On the other hand, the sign and the dependence of
Δk are the same with
Hk. Both the correspondences were explained qualitatively on the assumption of the anisotropic packing of crystallites.
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Kazuyoshi Ichinose, Katsuyuki Fujiwara, Hiroshi Yoshie, Hiroyuki Nagai ...
1982 Volume 51 Issue 12 Pages
3853-3856
Published: December 15, 1982
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Nuclear magnetic resonance of
59Co nuclei in Gd
1−xY
x(Fe
.7Co
.3)
2 and Gd
1−xY
x(Fe
.5Co
.5)
2 has been observed at 77 K as a function of Y concentration. The contribution of 4f electrons of Gd atoms to the hyperfine fields is estimated as at most 10 kOe in these two systems. This value is interpreted as the sum of the change in three kinds of contributions caused by Y substitution; the core polarization in the central Co atom, the conduction electron polarization arising from nearest neighbor Fe and Co atoms and the transferred hyperfine field from neighboring Gd atoms. The temperature dependence of resonance frequencies in Gd(Fe
.7Co
.3)
2 and Gd(Fe
.5Co
.5)
2 has also been measured.
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Makoto Kuburagi, Takashi Tonegawa, Junjiro Kanamori
1982 Volume 51 Issue 12 Pages
3857-3867
Published: December 15, 1982
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The cluster variation method is applied to calculate a temperature versus magnetic field phase diagram for the triangular Ising lattice with antiferromagnetic nearest-neighbor (nn) and ferromagnetic next-nearest-neighbor (nnn) interactions. Calculations are performed within the nn equilateral triangle plus nnn equilateral triangle approximation as well as within the molecular field approximation. The phase diagrams obtained within the former approximation are in good agreement with the Monte Carlo results of other authors except in the region of small magnetic field. The temperature and magnetic field dependence of sublattice magnetizations, total magnetization, specific heat, and susceptibility is calculated. A brief discussion is given in connection with experimental data on CsCoCl
3 and CsCoBr
3.
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Masashige Onoda, Toshihiro Takahashi, Hiroshi Nagasawa
1982 Volume 51 Issue 12 Pages
3868-3875
Published: December 15, 1982
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The electronic states of the V
4+ ions in β-Na
0.33V
2O
5 are studied by NMR and EPR measurements. The anomalous temperature dependence of the Knight shift of the
51V nuclei in site I can be understood by the spin singlet ground state of the electron pairs of the adjacent V
4+ ions (bipolarons). Recent X-ray diffraction measurements reveal that this paired state is accompanied with the small ionic displacement, as predicted by Chakraverty
et al. and the long range ordering of the bipolaronic state in the real space occurs below 200 K. From analyses of the anisotropic Knight shift and the quadrupole interaction, the electron wave function of the V
4+ ions in site I is found to be mainly made of the
dyz-orbitals. The EPR results show that there are two components of the spin states: the bipolaronic spin singlet and the dilute isolated paramagnetic states.
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Akira Nagasawa, Tomoko Makita, Yukiko Takagi
1982 Volume 51 Issue 12 Pages
3876-3881
Published: December 15, 1982
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We obtain the third order elastic constants in the β
1 phases of Au–Cu–Zn and Cu–Al–Zn alloys by measuring the pressure dependence of the second order elastic constants under the uniaxial pressure. The β
1 phases are highly anharmonic. In any alloy, the free energy barrier to form the martensite is of the order of only meV/atom. We also calculate the pressure derivatives of the second order elastic constants as a function of the pressure directions. They are considerably anisotropic. Using the results, we consider the martensitic nucleation. The martensitic nucleation mechanism is originated from the anharmonic property of the β
1 phase.
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Kazuhide Tanaka, Mutsumi Yoshino, Kenji Suzuki
1982 Volume 51 Issue 12 Pages
3882-3887
Published: December 15, 1982
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The electronic structures of transition metal (Fe, Ni)-metalloid (B, Si, P) alloy glasses are investigated by soft X-ray spectroscopy. In Fe-based alloy glasses a single peak is commonly observed at 4∼6 eV below the emission edges of the B
Kα, Si
Kβ and P
Kβ spectra, while a weak hump is seen at the bottom of the main peak of the Fe
Lα spectrum. Similar data are obtained for Ni-based alloy glasses. These results are consistent with recent band calculations on amorphous Fe–B and Fe–P alloys by Fujiwara, and can be explained in terms of bonding-antibonding splittings of the metalloid
p bands hybridizing with the transition metal
d bands. It is concluded that chemical bonding among the constituent atoms contributes to the stabilization of these metallic glasses.
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Masatoshi Tanaka, Goro Kuwabara, Hirohito Fukutani
1982 Volume 51 Issue 12 Pages
3888-3892
Published: December 15, 1982
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The structure of the conduction bands in the layered MoS
2, MoSe
2, WS
2 and WSe
2 is discussed from the metal ion-dependence of the effective
g-values of the A and B excitons with including both the spin-orbit and the interlayer interactions. It is concluded that the
Γ8+ conduction band is located below the
Γ9− conduction band in Mo chalcogenides and vice versa in W chalcogenides. The existence of the closely located interlayer split pair bands, arising from the two-dimensional nature of the layered structure, is found to be important for the chemical dependence of the
g-values of the excitons.
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Tsuneya Ando
1982 Volume 51 Issue 12 Pages
3893-3899
Published: December 15, 1982
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The subband structure of a two-dimensional electron system at a GaAs/Al
xGa
1−xAs heterojunction interface is calculated. Many-body exchange and correlation effects are taken into account in the local density-functional approximation. They are shown to be unimportant but not negligibly small. Spectra of light scatterings are also calculated. Results are in reasonable agreement with existing experiments.
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Tsuneya Ando
1982 Volume 51 Issue 12 Pages
3900-3907
Published: December 15, 1982
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The low temperature mobility is calculated in a two-dimensional system at a GaAs/Al
xGa
1−xAs heterojunction. Scattering mechanisms are assumed to be the Coulomb scattering from ionized donors in the Al
xGa
1−xAs layer, interface roughness, and scattering caused by alloy disorder present in the Al
xGa
1−xAs layer. The calculated mobility for the Coulomb scattering explains recent experimental results. The interface roughness and the alloy scattering can play a role at high electron concentrations (∼10
12 cm
−2).
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Yutaka Shinba, Koichi Nakamura, Mitsuru Fukuchi, Makoto Sakata
1982 Volume 51 Issue 12 Pages
3908-3914
Published: December 15, 1982
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The rate of electron energy loss to surfons in Si(111) inversion layer is found theoretically to be given by −〈dε⁄d
t〉=λ
Te5 for very low lattice temperature
T<<
Te<<4×[
Ns⁄(10
12cm
−2)] K irrespective of the phonon modes, the relation being the same as the one we found previously for the (100) surface. The relation as deduced from Ono
et al.’s experiment (
T=10 mK,
Te\lesssim2 K,
Ns=1.6×10
13 cm
−2) agrees well with our prediction in the
Te-dependence, but not in the value of λ.
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Yasuaki Masumoto, Yutaka Unuma, Shigeo Shionoya
1982 Volume 51 Issue 12 Pages
3915-3919
Published: December 15, 1982
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The self-trapping time of 1
s excitons in KI is directly measured for the first time by using the picosecond pulses of fifth harmonic (212.8 nm) of a Nd
3+ : YAG laser, which is one-photon resonant to the 1
s exciton. By observing the rise time of the
Ex luminescence, the self-trapping time is estimated to be 100±50 ps. This self-trapping time is considered to be the time for the excitons to tunnel the adiabatic potential barrier. The self-trapping time and the barrier height, 30 meV, are compared with theoretical calculation and consistency of these values is discussed.
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Kazunori Aoki, Kouichi Miyamae, Toshihiko Kobayashi, Keiichi Yamamoto
1982 Volume 51 Issue 12 Pages
3920-3928
Published: December 15, 1982
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The cross sections for electron-exciton elastic collisions in semiconductors have been calculated by use of Hulthen’s variational method. Both the electron exchange effect and the effect of the distortion of the 1
s exciton wave function have been taken into account. The collision broadening
Γ of the exciton luminescence and the spin relaxation time in GaAs have been calculated and compared with experimental results.
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Yukikuni Akishige, Tsutomu Kubota, Kikuo Ohi
1982 Volume 51 Issue 12 Pages
3929-3935
Published: December 15, 1982
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Electron spin resonance spectra of Fe
3+ in single crystals of Sr
2Ta
2O
7 and Sr
2Nb
2O
7 have been investigated at 180°C and 250°C, respectively. The spectrum of Sr
2Ta
2O
7 is attributed to four orthorhombic Fe
3+ centers. Two of them show a super-hyperfine splitting at the liquid nitrogen temperature. Other two centers are also observed in Sr
2Nb
2O
7 at 250°C. Angular dependence of the spectra are described by a spin Hamiltonian with second order terms,
D and
E. The ratios of
E to
D and the directions of the principal axes for these centers are determined. Brief discussion on the site assignment of these Fe
3+ centers is given.
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Katsuhiro Kohda, Nobuo Nakamura, Hideaki Chihara
1982 Volume 51 Issue 12 Pages
3936-3941
Published: December 15, 1982
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Proton spin-lattice relaxation time
T1 was measured at 19.5 MHz of
p-terphenyl in the vicinity of its solid-solid phase transition point. A sharp decrease in
T1 was observed near the transition point and was attributed to the critical fluctuation associated with the phase transition. The
T1 was interpreted successfully in terms of the order-disorder mechanism by which the central phenylene ring jumps between two stable sites in a double minimum potential well and its motion undergoes a critical slowing down in the phase transition region. The possibility of displacive phase transition was also discussed.
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Minoru Fukui, Ryuji Abe
1982 Volume 51 Issue 12 Pages
3942-3947
Published: December 15, 1982
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ESR line shape of VO
2+ ions has been studied in the incommensurate phase of K
2SeO
4 crystal. The line shapes near the commensurate-incommensurate transition were analysed by the one-dimensional phase soliton model. The theoretical line shape agreed well with the experimental one. The temperature dependences of the density and the initial phase of the soliton were obtained from the line shape fitting.
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Takeyo Tsukamoto, Jun Hatano, Hideo Futama
1982 Volume 51 Issue 12 Pages
3948-3952
Published: December 15, 1982
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When a laser beam transmits through an
a-cut plate of Rochelle salt in the ferroelectric (simultaneously ferroelastic) phase, two types of weak intensity beams deflected from the direct beam direction are observed. The relation between the angle of incidence and the angle of deflection, and polarizing directions of light are satisfactorily explained by refraction and reflection at a domain wall, on both sides of which refractive indicatrices are mutually inclined a few degrees. The refraction and reflection occur at equal angles, and the respective polarizing directions are symmetrical with respect to the wall. There exists a critical angle of incidence, above which one type of deflection beams appears. Diffraction effects due to multi-walls do not account for the experimental results.
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Takashi Ueda, Satoshi Iida, Hikaru Terauchi
1982 Volume 51 Issue 12 Pages
3953-3957
Published: December 15, 1982
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The successive phase transitions in Rb
2ZnBr
4 are carefully examined by the X-ray diffraction. At the incommensurate-commensurate phase transition temperature
T2=200 K, supercooling effect is observed together with the thermal hysteresis. Below
T3=108 K, the intensity of the (8 0 0) reflection decreases with decreasing temperature, corresponding to the decrease of the spontaneous polarization in the
a-direction. The space group below
T4=80 K is suggested to be
Cs2-
P1
c1 or
C2v4-
P2
cm. The phase transition at
T5=50 K depends on the heating rate.
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Naoyuki Mishima, Kazuyuki Itoh, Eiji Nakamura
1982 Volume 51 Issue 12 Pages
3958-3965
Published: December 15, 1982
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The crystal structure of Ca
2Sr(C
2H
5CO
2)
6 in the ferroelectric phase was determined at −40°C by X-ray reflection data from a monodomain crystal. The least-squares calculation was converged with the
R-factor of 0.044. Among the six independent propionate ions in a formula unit, four ones which are disordered perfectly in the paraelectric phase are in partially disordered states with two equilibrium atomic positions. Correlation between the positions of methyl groups in the disordered propionate ions is discussed on the basis of the van der Waals version.
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Atsuo Fukumoto, Akira Ueda, Yasuaki Hiwatari
1982 Volume 51 Issue 12 Pages
3966-3973
Published: December 15, 1982
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As a simple model for α-AgI, a system with ionic potentials consisting of only a Coulombic and a soft-core repulsive terms is investigated with use of a molecular dynamics method. The system has interesting scaling properties and is characterized by the ratio of the ion core radii and
Γ, the ratio of potential strengths between the Coulombic and soft-core terms. It is shown that there exists a range of
Γ in which the iodine sublattice forms a stable bcc structure and silver ions are disordered. The
Γ- and temperature dependences of various quantities are examined. In this range of
Γ the diffusion and the density distribution of silver ions are in accord with the experiments.
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N. Milinski
1982 Volume 51 Issue 12 Pages
3974-3976
Published: December 15, 1982
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By two partial integrations in succession, Kubo’s formula for electric conductivity σ(ω), has been reduced to an expression giving σ(ω) by a force-force time correlation functions, which in the limit ω→0 behaves like an indeterminate ratio (0/0). This ratio has been resolved by the use of L’Hospital rule, and has given an expression for DC conductivity, which is suitable for practical calculation, more than original Kubo’s formula.
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N. Milinski
1982 Volume 51 Issue 12 Pages
3977-3984
Published: December 15, 1982
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Formula for electric resistivity ρ, derived in the first part of this work has developed to the case when the coupling of carriers to the rest part of many particle system, can be described by a local pseudopotential, like to the case of liquid metals and alloys. Resistivity of liquid alkali metals has been calculated, and specific lines of numerical calculations by the new formula have been analysed and comments given. According to our results, the scattering of carriers accompanied by the wave vector transfer in amount of
q, is of essential importance, not only for
q<2
kf, but also for
q above of double Fermi radius
kf,
q>2
kf, in opposite to the Ziman’s formula, which takes into consideration and accounts only the region
q<2
kf.
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Isao Miyake, Hideo Futama
1982 Volume 51 Issue 12 Pages
3985-3989
Published: December 15, 1982
Released on J-STAGE: May 29, 2007
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Luminescence induced by 100 kHz ultrasonic excitation in X-rayed KCl crystals which previously are heated in chlorine vapor is observed at room temperature. Under prolonged excitation by a constant ultrasonic stress amplitude, the luminescence continues during initial several tens seconds. Simultaneous measurements of internal friction are carried out by the Marx’s method in order to reveal a role of dislocation motion in the luminescent processes. Existence of critical strain amplitudes was found above which the luminescence becomes notable and the internal friction indicates an abrupt increase. The results are discussed with the vibrating string model of dislocation motion, and it is concluded that excitation of color center’s electrons is caused by unpinning of dislocation and that the unpinning process annihilates defects that have pinned the dislocation.
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Kin-ichi Masuda, Minoru Hashimoto, Yoichi Ishida, Ryoichi Yamamoto, Ma ...
1982 Volume 51 Issue 12 Pages
3990-3997
Published: December 15, 1982
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A tight-binding type electronic theory is used to calculate the configurational and electronic structures of coincidence-related tilt grain boundaries in bcc transition metals α-Fe, Mo and W. To obtain the atomic configurations near the grain boundaries, both electronic (d-band) and repulsive energies are calculated and minimized: The change in the d-band energy
ΔEd is obtained using the second moment Gaussian approximation for the d-density of states (DOS), while the Born-Mayer potential is used to estimate the change in the short-range repulsive energies. It is shown that the grain boundary structures depend sensitively on the species of transition metals, and the asymmetric grain boundaries can be stabilized for certain transition metals. We also present the local DOS of d-electrons, calculated using the recursion method, on the atomic sites near the tilt grain boundaries.
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Ikuo Fujita, Toshiyuki Suzuki, Yoshihiro Miwa
1982 Volume 51 Issue 12 Pages
3998-4002
Published: December 15, 1982
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Thallium concentration in KDP: Tl crystals is measured by spectroscopic analysis of their aqueous solutions. It is confirmed that the strengths of the five uv absorption bands (
Axy,
Az,
Bxy,
Cxy and
Cz) are linearly proportional to the thallium ion concentration in the crystal. Oscillator strengths of these bands are also determined and are compared with those for Tl
+-like centers in KCl. The oscillator strength of the crystal field induced transition associated with the
Bxy band in KDP: Tl is 0.10 at 77 K, which is about one order of magnitude larger than that of the phonon induced transition associated with the B band in KCl: Tl.
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Ichiro Aoki
1982 Volume 51 Issue 12 Pages
4003-4010
Published: December 15, 1982
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The specific intensity of energy radiation reflected diffusely by a large sphere (or scattered by a small particle) is examined. The entropy change in diffuse reflection of radiation by the sphere (or in scattering) is given and shown to be positive. If incident radiation is black-body radiation and if the reflectivity (or the scattering ratio) is independent of frequencies of radiation, energies and entropies of diffusely reflected (or scattered) radiation can be treated as those of grey-body radiation. Effects of multiple-scattering of radiation are discussed. Results are applied to solar radiation reflected by the earth and also scattered by the atmosphere.
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Ichiro Aoki
1982 Volume 51 Issue 12 Pages
4011-4014
Published: December 15, 1982
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The spectral specific intensities of energy radiation split into two parts by a thin beam-splitter are given. The spectral specific intensity of incident entropy radiation
L0(ν) and those of split entropy radiation
L1(ν) and
L2(ν) satisfy an inequality
L0(ν)<
L1(ν)+
L2(ν). It is shown that the radiation entropy always increases in beam-splitting. As an application, solar radiation incident upon the earth is considered.
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Katsuhiko Nagai
1982 Volume 51 Issue 12 Pages
4015-4020
Published: December 15, 1982
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X-ray diffuse scattering due to orientational disorder is discussed in the disordered phase of a crystal having molecules with multiple orientations. The Bethe approximation is extended to multi-orientational system so that the short range correlation can be incorporated in the correlation function. The intensity of the diffuse scattering is written in terms of the probabilities of the pair configurations of the neighboring molecules.
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Keizo Ishii, Masao Sebata, Masami Kamiya, Akira Kuwako, Susumu Morita, ...
1982 Volume 51 Issue 12 Pages
4021-4027
Published: December 15, 1982
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K-shell ionization cross sections of five elements in the range from Ca to Cr have been measured for α-particle and N
7+-ion bombardments at projectile energies of 5, 6 and 7 MeV/amu. Contributions from the binding energy effect, the polarization effect and the electron transfer effect to these inner-shell ionization are investigated. From the (
Zp⁄
Zs)-dependence of the inner-shell ionization cross section, where
Zp is the projectile charge and
Zs is the effective atomic number of target atoms, it is found that the binding energy effect and the polarization effect cancel out each other in the present impact-energy region and the charge-transfer cross section is proportional to (
Zp⁄
Zs)
5.
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Kimichika Fukushima, Junya Mizuno, Kazumi Fujima, Hirohiko Adachi
1982 Volume 51 Issue 12 Pages
4028-4035
Published: December 15, 1982
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In order to improve the accuracy for the Diophantine integration scheme in the discrete variational
Xα method, which makes orbital calculations with non muffin-tin potential for large systems, it is proposed to use Gaussian quadrature (GQ) for integrating the Hamiltonian and overlap matrix elements. The values for these quantities show very good convergence with a relatively small number of sampling points. The total energy calculations as well as orbital energy calculations are carried out for diatomic CO and C
2 molecules. The calculated dissociation energies reasonably agree with experimental data. Equilibrium bond distances, however, are somewhat larger than the experimental value. The present method has been applied to diatomic FeO molecule. The bond distance and bond energy for this molecule are discussed.
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