The nuclear emulsions loaded with ⁶Li were irradiated with 32 MeV bremsstrahlung X-rays. A clear discrimination of the reactions was made by the use of a momentum balance method. The ⁶Li(γ, t)³He cross section shows a peak at E_γ\simeq21 MeV with the maximum value 5.1 mb. The angular distribution of phototritons corresponding to the peak energy shows an asymmetry around 90°, indicating an interference between E1 and E2 absorptions. The ⁶Li(γ, pd)³H cross section has the maximum value 5.8 mb at E_γ=24∼25 MeV. The cross sections of these reactions integrated up to 32 MeV are 12.8±1.9 mb·MeV and 18.2±2.0 mb·MeV, respectively. They make the total integrated photon absorption cross section to have a reasonable value expected from the E1 sum rule. Present data are compared with the predictions of the models for ⁶Li proposed so far.

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The n-p differential cross sections at 14.1 Mev were measured with a counter telescope at 8 angles in the range from 172.0° to 52.5° in the center-of-mass system. A least squares fit of the data gives the center-of-mass differential cross section: σ(Θ_n)=52.9 (1−0.0639cosΘ_n+0.0288cos²Θ_n) mb/sr, which is clearly asymmetric about 90°. The ratio of the cross sections at 180° and 90° is 1.093±0.022, and the total cross section is 671±10 mb. The present results are in good agreement with the theoretical results based on the one-pion-exchange potentials.

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The eigen-functions and eigen-values of finite three-dimensional Heisenberg models with anisotropy constant as a parameter (spin=1/2) were obtained exactly with the aid of group theoretical technique and by using a high speed computer.
The calculated eigenvalues are identical with those obtained by Serber and Dresselhaus for the isotropic simple cubic 2×2×2 lattice. However, it was found that some terms in their full expressions were to be corrected. The zeros of the partition function of the above 2×2×2 lattice have been investigated as functions of the anisotropy parameter both in the complex temperature plane and in the complex magnetic field plane. Thermodynamic functions such as energy, specific heat, magnetization, and susceptibility have been numerically computed for these finite system.

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The Magnetic co-operative phenomena in two-dimensional Heisenberg spin system diluted with non-magnetic ions, Mn_xMg_(1−x)(HCOO)₂·2H₂O, were studied by measurements of the specific heat and magnetic susceptibility. The Néel temperature T_N(x), associated with the antiferromagnetic long range ordering, ran down linearly to the lower temperature side for 0.76<x<1.00. The critical concentration was estimated to be about 0.60 from the disappearance of the sharp peak on the specific heat curve which indicates the phase transition. By diluting the system with non-magnetic ions Mg²⁺, we could observe in the specific heat curve the long range ordering peak and the broad maximum characteristic of short range ordering at separated temperatures. The appearance of the sharp peak and the broad maximum in the cource of dilution can be explained by that in the Ising spin system in two dimensions. Form these results, the behaviour similar to the Ising spin system and the two-dimensionality of this Mn²⁺ ion salt are discussed in comparison with other experiments and theoretical results.

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The valance band structure of tellurium near the corner of the Brillouin zone is derived, with the use of the group theory and the k·p perturbation method. The main features of the obtained valence band are the existence of the k_z-linear term and of the trigonal warping about the k_z axis. Because of the k_z-linear term Sk_z, the uppermost valence band has a double maximum or a single maximum, depending on the ratio of S²⁄4B|Δ₁| larger or smaller than one, where Δ₁ and B are the spin-orbit interaction and band parameters, respectively. The present theory is also applicable to selenium.

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Various barium orthoferrates over wide Fe⁴⁺ concentrations were prepared and their magnetic properties were investigated. The hexagonal phase with large Fe⁴⁺ concentration is ferromagnetic above the anomaly point. With increasing Fe³⁺, it tends to be antiferromagnetic. The cubictetragonal phases are paramagnetic with positive paramagnetic Curie temperature. In these phases, the Fe⁴⁺–Fe⁴ interaction is ferromagnetic, but the Fe³⁺–Fe⁴⁺ and Fe³⁺–Fe³⁺ interactions are antiferromagnetic. Some of the Fe³⁺ and Fe⁴⁺ ions in these phases take low spin states due to strong uniaxial crystalline fields caused by neighbouring oxygen vacancies. The triclinic I phase seems to have a magnetic structure of one-dimensional antiferromagnet. The magnetic structures of the triclinic II and rhombohedral phases resemble that of the triclinic I.

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There is evidence that there is significant exchange coupling of an impurity in a rutile structure antiferromagnet to spins other than its next nearest neighbors, in contrast to the situation in the pure materials. In this paper two modifications of the coupling scheme are considered and an analysis is made of the resultant alterations in the localized magnon spectrum. The numbers and symmetries of these local modes are relatively unambiguous indicators of the from of the exchange, and their energies will then determine experimentally the coupling strengths. Thermodynamic Green’s function techniques are used; decoupling in the RPA gives approximate predictions of the temperature dependence of the local mode energies. However, numerical results are given here only for zero temperature, and these are discussed in terms of a simple classical picture.

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Stripe domains were observed in oblique-incidence 40-100% Ni–Fe films prepared at incident angles from 57° to 75° with thicknesses above 450Å of either sign of uniaxial anisotropy. Lorentz microscopy at 100 kV reveals the structure of the domains as follows: 1. domain width is 1000-3500Å and constant within a film, 2. in-plane component of magnetization is parallel to the incident direction, thus they are named “negative stripe domain”, 3. magnetization inclines at an angle below 60° from the film plane, and 4. both normal and in-plane components of magnetization change the direction in two neighboring domains. This structure can be considered analogous to that of an expanded cross-tie wall.
At low frequency magnetization reversal, the negative stripe domains behave as a group and cause a two-stepped constricted hysteresis loop. The origin of these negative stripe domains is discussed in connection with the shape and pile of elongated columnar grains.

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Calculations the Heine-Abarenkov potential parameters for fcc Palladium are presented based on a Thomas-Fermi treatment of the activation energy for diffusion of screened interstitial protons.

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The electrical conductivity σ, the phonon-drag thermoelectric power S_L, and the low-field Hall coefficient R of copper are calculated with the variational method. The band structures of Burdick and the measured phonon spectrum are used in the calculation. The parameters in the electron-phonon coupling are adjusted to the observed electrical conductivity. The room temperature value of R is smaller than the observed one by 20%, and this discrepancy may be ascribed to the large s-d hybridization in Burdick’s bands. The temperature dependence of R agrees reasonably well with the observation above 50°K. It is noted that below 50°K, existing measurements for pure samples do not satisfy the low-field condition. The phonon-drag effects on σ and R are proved to be negligibly small. The calculated value of S_L is positive above 30°K and large enough to explain the observed hump around 70°K, while it becomes negative below about 30°K, consistent with the experimental results.

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Dyson effect was investigated in the electron spin resonance of phosphorus doped silicon to know the dynamical characteristics of the paramagnetic center responsible for the single adsorption line around g-value of 2. Experiments were carried out at room, liquid nitrogen and liquid helium temperatures using samples of rod shape containing phosphorus atoms about 10¹⁷, 10¹⁸ and 10¹⁹ cm⁻³. Theoretical line shape was calculated to simulate the effect of parameters such as sample thickness, skin depth and diffusion time of electrons through the skin depth. The observed absorption line showed distortion consistent with the Dyson theory. The diffusion time was estimated to be several times of the electron spin relaxation time. Comparing with the diffusion time calculated from the electron mobility, a model is proposed that there might be two types of electron motion, namely rapid motion in an impurity cluster and slow transitions among the clusters.

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The effective sound velocity S_q(C) is deduced in the case of ql<1 taking into account the linear loss of phonon system. Using this term, drift mobility in CdS can be obtained from the ratio S_q(C)⁄E_th, where E_th is the threshold field of the current saturation in voltage-current characteristics in CdS.

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Absorption intensities of two exciton bands in CuCl–CuBr solid solutions, the Z_1,2 and Z₃, due to the spin-orbit splitting have been measured. In CuBr the Z_1,2 band has a larger intensity than that of the Z₃ but with increasing the Cl-doping the difference in intensities of two bands becomes small and in a solution Cu(Br_0.23Cl_0.77), where the spin-orbit splitting is zero, the Z_1,2 band becomes very weak compared with the Z₃. The intensity variations of exciton bands are explained well by the theory of exchange interaction of Onodera and Toyozawa. The CuCl–CuBr system is found to be a suitable example where the effect of the exchange interaction appears remarkably.

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Properties of intrinsic and bound excitons in CdS with Cl donor concentrations over a wide range are investigated by measuring emission and reflection spectra at liquid helium temperature. As a result two characteristic properties of excitons are observed. 1) The binding energy of excitons decreases with increasing donor concentration, but the dependence on the concentration is different between intrinsic and bound excitons. 2) The emission line due to bound exciton shows asymmetric broadening with a tail extending to lower energies at high donor concentrations. According to Hanamura’s theoretical work in the succeeding paper, the first behavior of the decrease of binding energy is ascribed to the screening effect of donor electrons on excitons. The second feature of anomalous line shape is concluded to be a consequence of the Stark effect due to charged impurities on bound exciton. On the basis of these interpretations very good agreement has been obtained between experiment and theory.

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It is pointed out that localized donor electrons participate dominantly in screening the electron-hole Coulomb attraction in the exciton around the donor concentration where the Mott transition is observed. The decrease in binding energies of intrinsic and bound excitons in CdS for increasing donor concentration, which was observed by Kukimoto et al. is explained by this screening effect. The peculiar feature of the asymmetric broadening with a long tail on the lower energy side in emission line shape of bound exciton is ascribed to the stark effect due to charged impurities.

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Energy transfer by dipole-dipole interaction between Tl⁺ ions in KI single crystals was studied with several kinds of crystals different in Tl⁺ concentration at low temperatures. Since two emission bands (2845 Å and 3044 Å) which appear under excitation at the B absorption band of Tl⁺ ions overlap with the A absorption band of the ions, there is a possibility of energy transfer by resonance from excited Tl⁺ ions to normal Tl⁺ ions. The absorption coefficient of the A band and the emission bands produced by excitation at the B band were measured; and, thereby, the critical transfer distance R₀ was obtained from Dexter’s formula. Furthermore, the decay curves of the donor emissions were measured by a pulse method and their shapes were analyzed with Eisenthal and Siegels’s theory. The values of R₀ thus obtained for 2845 Å and 3044 Å emissions were 35 Å and 26 Å, respectively. They were in good agreement with those obtained from Dexter’s formula, that is, 33 Å and 24 Å respectively.

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Luminescence from binuclear complex salts of Cr³⁺ ion is investigated at low temperatures for the first time as to rhodo-chloride, rhodo-chloride-perchlorate, rhodo-perchlorate and basic rhodo-chloride. The spectral features are dependent on the nature of the bridging groups. In the emission spectra of hydroxo-bridging compounds several sharp lines are observed at around 6800Å within an energy range of about 120 cm⁻¹, and these lines are followed by vibrational structure extending to 7200Å. In the oxo-bridging complex, the spectrum involves two broad bands besides the sharp lines. The sharp lines are interpreted as orginating from Cr³⁺ ion pair due to the transition corresponding to the R lines in ruby, while the broad band observed in the oxo-bridging compound as being due to the reverse transition of the U absorption band. A superexchange interaction of the Heisenberg type is shown to be responsible for the features of the pair spectra. The theoretical analysis is transferred to Part II. The superexchange interaction is also considered to play an important role for the formation of unusual plateaus observed in the temperature dependence curves of emission intensities.

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The experimentally observed sharp line luminescence from Cr³⁺ ion pair in binuclear complex salts, described in Part I, is interpreted theoretically by taking account of the splitting of the ground and excited states of Cr³⁺ ion due to an anisotropic exchange interaction of the type J₀s^a·s^b+Js_z^as_z^b. Employing Sugano and Tanabe’s theory, we have obtained the energy levels and transition dipoles from the symmetry consideration. The parameters were adjusted so that the best fit between the experimental results and the theoretical analysis is given. The observed spectra were thus well interpreted as being due to the transitions of Cr^*(²E)Cr(⁴A₂)→Cr(⁴A₂)Cr(⁴A₂) between the states of different total spins. From this we estimated the values of J₀ which are consistent with those obtained from magnetic measurement, though some discrepancy was found for basic rhodo-chloride. It was also suggested that the weak lines found in the excitation spectra at 4°K are caused by the two ion excitation mechanism.

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Calcium fluoride crystals, which exhibit a weak four band spectrum (Smakula bands) on coloration by X-rays, are found to be colored by low energy electrons (∼10 kV) in the temperature range of 150 to 400°C, and show only two bands. A spectrum exhibiting the α and β bands of Mollwo can be produced even at 28°C if the crystals are X-rayed prior to electron bombardment. The results are explained by the fact that low energy electrons, because of their short range, can affect a negligibly small number of impurity ions; the effects of trace impurities can, thus, be avoided by this method of coloration. It is, further, concluded that diffusion of neutral fluorine atoms takes place during the electron bombardment and thereby facilitates the formation of F centers. The experiments of the bleaching of X-rayed crystals under electron bombardment also provide supporting evidence for the diffusion of trapped holes (F° atoms).

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Far-infrared reflectivity spectra of KH₂PO₄ crystal were measured from 16 to 400 cm⁻¹ at the temperature range from 83 to 300°K, and complex dielectric constants were derived using a K.K. dispersion relation. The low frequency dispersion in c-polarization exhibits remarkable characteristics; (1) the high frequency tail drops far more steeply than ω⁻³ (in ε″), and shows only a slight temperature dependence, (2) a significant structure is recognizable in the low frequency side slightly above the Curie point.

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In order to investigate the electron state in BeO, the Compton profile has been measured on a powder sample by use of AgKα radiation. On the other hand, theoretical profiles have been calculated from available four sets of electron wave functions, which mostly concern isolated atoms.
Comparison of the observed profile with the theoretical ones showed that wave functions of Be⁺⁺O⁻⁻ state are better than those of BeO and Be⁺O⁻. However, there still remains small discrepancy, which may be due to complexity of chemical bond in solid state. In the appendix, a numerical table is given for the theoretical Compton profiles due to atoms, Be⁺, Be⁺⁺, O⁻ and O⁻⁻, which have not so far been published.

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The time changes in the amplitude dependent internal friction are studied in β-tin crystals, 99.99% pure, and oriented for the [001] slip. The measurements are made during the free decay of transverse vibration. Comparison of the results with the theory of Granato and Lücke leads to the following conclusions:
(a) The length of movable dislocation increases as the amplitude of excitation is increased.
(b) The length also increases with the duration of excitation at constant driving force, as log(γt+1). This is considered to be due to breakaway from the atmosphere of solute atoms. After the breakaway, the diffusion of solute atoms from the atmosphere of the movable dislocation takes place, around room temperature. At low temperatures, the diffusion does not take place, but the brokenaway dislocation moves large distances in the lattice. The amplitude dependent internal friction is in this case caused by the interaction of the movable dislocation with the solute atoms distributed in the lattice.

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Three dimensional observation of individual dislocation lines constituting indentation rosette was made by electrolytic decoration. The majority of lines belonged to systems of loop families of {110} and {112}. From the structure, the formation of rosette was inferred to consist of the initial stage where the elemental glides operate, and the rearrangement stage where cross glide, climb, multiplication and network formation also operate. Upon applying external stress by bending and compression the rosette structure transformed to an arrangement more complicated than that expected. Causes of the complication are the plastic deformation and residual strains around indent. Mechanical and electrostatic motives may explain the characteristic transformation.

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The contribution from π-electrons in base pairs to the conformation of DNA molecule is studied. As model substances, homo-oligomers of stacked purine and pyrimidine base pairs are considered. By the perturbation method in the LCAO MO scheme assuming the zero-differential overlap between monomers, the intermonomer interaction energy is calculated as a function of the helical angle θ between monomers and the monomer-to-monomer distance p along the helix axis. The effect of the overlap is taken into account by the short range repulsion term estimated by a semiempirical formula. The minimum in the interaction energy occurs at p=3.7Å and θ=80° for the pentamer of guanine-cytosine pairs, and at p=3.4Å and θ=58.5° for that of adenine-uracil. It is discussed why calculated θ-value differs from the experimental one 36°.

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A theoretical consideration of nearly resonant interaction between the infrared radiation and the anharmonic molecular vibration has been developed to evaluate an efficiency of third harmonic generation in the infrared by molecules. By using the spectroscopically measured molecular constants in the Morse function, the nonlinear susceptibilities for second and third harmonic generation are derived. The problem is treated both classically and quantum mechanically. It is found that the spectroscopic stability holds for the nonlinear susceptibility. Non-resonant interactions which usually occur in solids are also discussed briefly.
A gas of molecules with random orientations cannot produce optical second harmonics. However, each molecule has the nonlinear susceptibility of second harmonic generation by its molecular vibration and it is found that the Miller’s rule also holds for the molecular susceptibility.

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The dielectric constants (ε′) and loss factors (ε″) of phenetole, aniline and orthochloroaniline in the liquid state at different temperatures in the 3 cm and 1.5 cm microwave regions have been measured. The results have been analysed in terms of two relaxation times τ₁ and τ₂ for molecular and intramolecular orientations respectively.

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Proton resonance at 40.5 Mc for the AlCl₃ solutions was studied at various pH and the temperature down to −29.5°C. The separate signals one for coordinated and the other for bulk water were observed at sufficiently low temperature. The former is separated from the latter to the lower side of magnetic field by 182.6 cps. Three kinds of reaction of proton exchanges, are assumed, namely (1) the proton transfer from Al⁺⁺⁺(H₂O)₆ to H₂O, (2) the proton transfer from Al⁺⁺⁺(H₂O)₆ to Al⁺⁺⁺(OH)⁻(H₂O)₅ via H₂O, and (3) the exchange of water molecule between solvation shell of Al⁺⁺⁺ and of H⁺. The corresponding rate constants k₂ and k₃ at −29.5°C in the reactions (2) and (3) were found to be 2.2×10⁵ sec⁻¹ mole⁻¹ 1H₂O and 1.8×10⁻⁴ sec⁻¹ mole⁻¹ 1H₂O respectively, and their activation enthalpies ΔH₂^* and ΔH₃^* were 20.9 kcal/mole and 4.9 kcal/mole respectively. The rate due to the reaction (1) was negligible as compared with those of the reactions (2) and (3).

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Ultrasonic absorption has been measured in three concentrations of CoSO₄, each at three temperatures. The dielectric constant of the medium is varied using three different water + methanol mixed solvents. The relaxation observed in the frequency range 30 to 100 mc is assigned of the first step of Eigen three step ion-association mechanism. The variation of the relaxation frequency and the rate constants with dielectric constant is as expected theoretically for a diffusion − controlled step. The activation energy values obtained by the ultrasonic technique agree with the results for viscous flow.

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Instability of a vertically accelerated horizontal two-dimensional interface between a liquid and air is found to be a singular perturbation problem and is solved by the method of strained coordinates. A third-order theory presented here completely alters the predictions of the linear theory, seeks to remove the defects in a previous non-linear theory and explains the experimental observations. The growth of disturbance occurs even at the critical wave-number predicted by the linear theory.

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Under some conditions waves can be confined in a moving boundary and propagated with it. Taking these waves into account, we classify various types of Doppler-effect-like phenomena. The results of an improved simulation experiment clarify characteristic natures of reflection and refraction of a wave or a pulse at the moving boundary. They are qualitatively explained with a schematic method.

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Non-linear density waves in a rotating stellar system are investigated within the framework of the gasdynamic approximation endowing the system with an isotropic pressure. The waves are assumed to be one-dimensional and steady in a uniformly rotating local coordinate system and to propagate at a constant velocity perpendicular to the axis of rotation.
The results show that the waves are wave trains for the cases of supersonic flows, and that the waves are wave trains, or solitary waves for the cases of subsonic flows.

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In order to see the qualitative properties of the Hall effect on the magnetogasdynamic flow past an axi-symmetric body at small magnetic Reynolds number R_m and larger Reynolds number R_e, the steady, incompressible, inviscid flow past a body of revolution at zero incidence is studied on the assumption that a magnetic field is parallel to the velocity at infinity upstream and the body is an insulater.
The equations governing the azimuthal components of the velocity and magnetic field are derived, being expanded in power series with respect to α²R_m, where α² is the pressure number.
A general method to solve these equations is discussed for the axi-symmetric obstacle of arbitrary shape at zero incidence, and the surface velocity, the magnetic field in the azimuthal direction and the electric field are determined for a sphere and a circular disc.

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