Self-consistent formulation of the incommensurate spin-density-wave (SDW) in chromium and its alloys is made by taking into account both the second harmonic charge-density-wave and strain-wave with a simplified model system. The order of the paramagnetic to SDW phase transition is studied on the basis of the Landau expansion of free energy. It is shown that the first order transition is possible if the electron-phonon coupling is sufficiently strong. Besides, it is found to be the situation favorable for the first order transition that the density of states of the reservoir is large and that the system is in the neighborhood of the commensurate-incommensurate transition point.

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Current fluctuations associated with the acoustoelectric instability is investigated theoretically within the Langevin approach. The behavior of the system is described by the motion of rotating-wave Van der Pol (RWVP) oscillators coupled to each other. When the power spectrum of current fluctuations is calculated in the single-mode picture disregarding the coupling between RWVP oscillators, its cutoff frequency is unrealistically small compared with the experimental value of 10 MHz. This difficulty is avoided by renormalizing the saturation parameters of individual RWVP oscillators. The noise power depends on the strength of the intensity correlation between different oscillators. When their motion is completely coherent, the noise power is much larger than the experimental value of 30 dB above thermal noise, while it becomes unrealistically small when the motion is completely random.

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The anomalous heat capacity Δc^X,E and thermal expansion Δα_j^X,E (j=1, 2, 3) of Rochelle salt at both Curie points were estimated from the measurement of thermoelastic effect by uniaxial pressures. The sign and amplitude of Δc^X,E agree well with those obtained from the calorimetric measurement by Tatsumi et al. (1974). Self-consistent thermal data of Δc^X,E and Δα_j^X,E were obtained in connection with the Ehrenfest relations.

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Measurements of magnetization, magnetic susceptibility, magnetocrystalline anisotropy and electrical resistivity were carried out at temperatures from 4.2 K to 700 K on Gd–Lu single crystal alloys. It was found that both of the saturation magnetic moment and the paramagnetic moment per atom are larger than those calculated by assuming a simple dilution of the ferromagnetic Gd with nonmagnetic Lu. The anisotropy constants at 4.2 K were drastically changed by addition of Lu. It is inferred that the excess moments and the drastic change of the anisotropy may be ascribed to the polarization of the 5d electrons of Lu atom site. From the measurements of the residual resistivity and spin disorder resistivity along the c-axis and b-axis, it is suggested that the occurrence of helical antiferromagnetism is associated with the distortion of the Fermi surface along the c-axis.

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Electron paramagnetic resonance of Mn²⁺ in a single crystal of tris-sarcosine calcium bromide (TSCBr), as a function of temperature and orientation, has been studied. These studies suggest the existence of two chemically equivalent but physically non equivalent Mn²⁺ site in a unit cell of TSCBr. Of the two space groups determined by neutron diffraction studies, Pnma and Pn2₁a, EPR studies are in conformity with the space group Pnma. The dielectric constant measurements in TSCBr do not show any anomaly in the temperature interval 300–100 K. Tris-sarcosine calcium chloride (TSCC, space group Pnma in the paraelectric phase) undergoes a ferroelectric phase transition at 127 K. Replacement of Cl by Br is expected to introduce changes in the N-H..X bond (X=Cl, Br) and hence, we believe, protons in the N-H..Cl bond may be playing an important role in the mechanism of ferroelectricity in TSCC.

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The Mössbauer spectroscopy has been applied to powder and single crystal samples of KFeF₃ between 4.2 K and 300 K. Thin slices of the single crystals with the {111} and {110} plane stressed along the respective plane were used to determine the orientation of the hyperfine field H_hf and the principal axes of the EFG tensors (X, Y, Z). H_hf and Z are parallel to the [111] direction between T_N=112 K and ∼65 K. Below ∼65 K a rotation of the principal axes of the EFG tensors takes place. Below T_c=41 K (T_c is defined in the text) H_hf is still parallel to the [111] direction within 5° but the principal axis Z of the EFG tensors lies in the (1\bar10) plane and makes an angle θ (40° at 4.2 K) to the [111] direction. The magnetization has been also measured for a single crystal between 4.2 K and 300 K. The weak ferromagntic moment parallel to the ⟨110⟩ direction was observed below T_c. A spin arrangement below T_c has been proposed.

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Submillimeter electron spin resonance was performed in a strong magnetic field up to 1 MOe. A newly developed theory shows that, in principle, one can produce an infinitely strong magnetic field without destroying coils when a stress-balanced multi-layer coil is used and the details are given in Part I. The practical application of the field generation and electron spin resonance using HCN and H₂O lasers are given in Part II.

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The multi-layer magnets based on the theory described in Part I were made and the maximum field was 1.07 MOe in a space of 2 mm in diameter with 5 mm in length. The submillimeter spin resonance in CuCl₂2H₂O was done using HCN laser and the exchange interaction J′ between dissimilar spins was determined as J′⁄k=0.67±0.08K. Compared to the main exchange value J between similar spins, J′⁄J=0.13±0.02 was obtained.

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The anisotropic exchange constants in diethylenetriammonium chlorocuprate are estimated by the spin wave analyses of the magnetic susceptibility. The anisotropy in the exchange constants is shown to be caused by two terms in the third order perturbation calculation.

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Ferromagnetic resonance measurements were performed on NiFe₂O₄ precipitates formed in single crystals of NiO containing Fe ions. It is concluded that the rhombohedral deformation of NiO below its Néel temperature is propagated into the NiFe₂O₄ precipitates and thus a uniaxial anisotropy is induced magnetomechanically in the precipitates besides the well-known cubic anisotropy. Furthermore, it is indicated that exchange interaction of spins across the interface between NiFe₂O₄ precipitates and the NiO matrix is also important at the early stage of the precipitation.

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Lattice parameters and thermal expansion have been measured on cementite partially substituted with Cr, Mn or Ni. The lattice-parameter-composition curves of (Fe_1−xCr_x)₃C and (Fe_1−xMn_x)₃C show notable anomalies at around x=0.08 for Cr and x=0.13 for Mn, where the Curie temperature of the alloys passed through the room temperature region. The lattice parameters at ferromagnetic state are larger than those at paramagnetic state. These compounds show an Invar type thermal expansion below the Curie temperature. These low thermal expansions in a narrow range around Fe₃C are caused by the large positive spontaneous volume magnetostriction in the ferromagnetic state.

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An experimental ¹¹B nuclear magnetic resonance study was performed in U_xY_1−xB₄ alloys. These alloys are known to be ferromagnetic below ∼14 K for 0.1\lesssimx\lesssim0.6. The nmr studies were performed in the paramagnetic temperature region 75–292 K to investigate the mode of development of 5f magnetic moments on the U atoms. The second moments of the nmr signals were analyzed to provide a measure of the distribution of magnetic fields within the alloys. The results are in qualitative agreement with a previously proposed theory suggesting that only those U atoms with four or less U nearest neighbors become magnetic. Quantitative agreement is provided if a reasonable assumption is made regarding the strength of the U magnetic moments.

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The magnetocrystalline anisotropy constants of disordered Ni–Pd alloys containing 20, 30, 40, 50, 60, 75 and 90 at% Pd have been studied in a range from 4.2 K up to the Curie temperature T_c by the use of the torque method. At 0 K, the first anisotropy constant K₁ of 20% Pd is much the same as that of Ni. Then K₁ varies rapidly accompanying a change in sign from negative to positive at 50% Pd and takes the maximum at about 65% Pd. The higher order constants K₂ and K₃ show a complicated dependence on the content of Pd. As temperature is raised, K₁ of the alloys with negative K₁ at 0 K changes the sign likewise Ni and the reduced temperature T⁄T_c where the sign changes, lowers as Pd increases. For the alloys with positive one, it decreases monotonically. Discussions are qualitatively made on K₁.

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Intensities of τ₂ components were small for pyrite (FeS₂) and Ni_1−xS. It was tried to explain those by the stoichiometry and the shielding of cation vacancies by s type conduction electrons. Enhancement factors were 1.8 for both NiO and NiS and there was no large enhancement in the conduction band of NiS.

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First order light scattering near the spin-flop transition point in antiferromagnets is studied theoretically. The anomalous increases are obtained in the light scattering intensities against an external magnetic field near the spin-flop transition point and also the transition point to the paramagnetic state at zero temperature. The case of finite angle of the applied magnetic field with respect to the easy axis is also examined. Numerical results are presented for MnF₂ and FeF₂.

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A high resolution neutron scattering study has been carried out on the charge ordering of magnetite below 123 K. Magnetic components were separated out by the application of magnetic field perpendicular to the c-axis which had been aligned by field cooling. Non-zero magnetic scattering was observed at (2, 0, l+1⁄2) referred to the cubic lattice, but not at (0, 0, 2), in contradiction to the previous report by Hamilton. This magnetic intensity distribution suggests the alternate Fe²⁺ and Fe³⁺ in the ab plane, in contrast to the Verwey model of the single modulation along the c-axis. Substantial disagreement remains between observed magnetic intensities and simple model calculations and further experiments are suggested to resolve this difficulty.

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The nuclear magnetic resonance of ⁹¹Zr in hexagonal close-packed Zr metal has been observed in the temperature range of 1.4–4.2 K and in the frequency range of 15–30 MHz by pulsed nuclear resonance technique. The resonance line profile showed a well resolved powder pattern due to electric quadrupole interaction. The quadrupole coupling constant was determined to be e²qQ⁄h=18.7±0.3 MHz. The isotropic Knight shift and the nuclear spin-lattice relaxation time were measured to be 0.33±0.02% and (T₁T)=30±5 sec K respectively and were discussed in terms of hyperfine interactions with the s- and d-band electrons.

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The electrical resistivity of a series of Fe₂A Laves phase compounds was measured in order to investigate its mutual correlation with their magnetic properties. In the ferromagnetic or antiferromagnetic Fe₂A compounds (A=Sc, Y, Ti, Zr, Hf, and U), a linear relation between the magnetic resistivity at temperatures above the Curie or Neel point and the localized magnetic moment was found, which means that the magnetic resistivity of these compounds is governed by the magnitude of magnetic moments. The electrical resistivity in the Pauli-paramagnetic Fe_2+xNb_1−x and Fe_2+xTa_1−x compounds with x≈0 shows a fairly large temperature variation, which seems to be due to the paramagnon scattering, whereas ρ-T curves in the iron-rich compounds suggest that the appearance of ferromagnetism is caused by the existence of the excess iron atoms occupying the wrong atomic sites.

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For Cu and α-phase Cu–Al alloys, the monovacancy formation energies which are in the linear decrease with increasing of the Al concentration have been obtained by means of the angular correlation method in positron annihilation. The results show that the formation energy in concentrated random alloys is due to the averaged potential. The formation energy of the 2nd multivacancy (divacancy mainly), E_F^2v, has been obtained using data in very high temperature: E_F^2v=2.20±0.05 eV for Cu, 2.30±0.06 eV for Cu–2.0 Al, the values of E_F^2v for other alloys are too large, do not show suitable values. The peak value curves for the substances have been obtained in the temperature under and above the melting point also.

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A linear theory of dipole radiation from piezoelectric semiconductors in the presence of acoustic amplification is presented, which shows the possibility that the radiation is of observable magnitude. Two processes are considered in succession, the amplification of electronic polarization current and the dipole radiation therefrom. The threshold field curve for radiation is calculated for n-InSb at 77K.

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The dispersion relation of the cyclotron waves for a layered electron gas is calculated numerically using the semiclassical magnetoconductivity tensor for the two-dimensional electron gas. The Voigt configuration is assumed with a static magnetic field perpendicular to the planes.

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Through the studies of excitation spectra of emissions in CuCl crystals by a frequency tunable dye laser, excitonic molecules have been found to be generated directly by the giant two-photon absorption at the photon energy of 3.187 eV, as suggested by Hanamura. Two-photon excitation of crystals at 1.6 K enhanced very narrow emission bands at 3.1647 eV and at 3.1709 eV. These photon energies coincide with those of the high energy edges of the M_L and M_T bands due to the radiative annihilation of excitonic molecules having K=0. From these facts the Bose condensation of excitonic molecules at K∼0 has been suggested.

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Properties of the 4.64 eV(UV) emission in KCl:I have been investigated under the excitation with light in a region from 6.5 to 7.7 eV. Measurements of optical spectra have been made at 80 K for KCl crystals doped with iodine ions of 8.1×10⁻⁴∼1.9×10⁻² mole fraction. The UV emission is found to be excited strongly on the low energy side of each of three monomer absorption bands. It is confirmed that intensity ratio of the UV emission to the 2.64 eV emission, which is due to monomer, increases linearly with iodine concentration. This fact indicates that at the low energy side of each monomer absorption, there exist absorption bands due to dimers of iodine ions, excitation of which leads to the UV emission.

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It has been confirmed that F centers in KI and NaCl single crystals are produced with a time constant shorter than 20 ns and 10 ns, respectively, between 10 K and 270 K under the pulsed electron beam from a linear accelerator. The F band due to these F centers is located at 1.87 eV and 2.75 eV in KI and NaCl, respectively, which is the same position, along with its half width, as that by a conventional x-raying coloration, and the height of the band stays almost constant after 20 μs or more indicating no recombination of F and H centers. The triplet state of the self trapped exciton in KI and NaCl is not directly connected to the F center formation as well as in KCl and KBr.

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Phonon side bands of uv absorption in NaNO₂ have been studied by the measurement of high resolution spectrum with light polarized along each crystallographic axis at low temperatures. Strong peaks in the side bands are assigned to the phonon branches in the first Brillouin zone by taking account of the selection rules for the optical transitions in which an exciton and a phonon are created simultaneously. The integrated intensities of the E⁄⁄b and E⁄⁄c absorptions have been found to increase with temperature obeying the coth(hν⁄2kT) law with ν_b\simeq220 cm⁻¹ and ν_c\simeq130 cm⁻¹ respectively. The relation between the temperature dependence of the E⁄⁄b and E⁄⁄c absorptions and the profiles of their phonon side bands is discussed in terms of the averaged phonon frequency \barν.

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The optical activity of crystals is investigated in terms of the crystal energy band theory. The ordinary optical activity is the spatial dispersion effect of light and is due to the ohmic current response caused by light field. The two sorts of contribution is specified, the matrix element term and the energy spectrum term. The latter term is directly related to the presence of k-linear terms is the energy dispersion E(k) at symmetry points in the Brillouin zone. The sum rule of the rotatory strength is derived and the Wannier exciton effect is discussed. The theory is applied to the optical rotatory dispersion of tellurium with the use of the known values of energy band parameters. The calculated dispersion curve is in good agreement with the experimental data. The optical rotatory dispersion of selenium is also discussed.

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The temperature dependence of the proton spin-lattice relaxation time T₁ of [(NH₄)_1−xK_x]₂SO₄ was studied. As the concentration of K₂SO₄, x increases, it is found that (1) the temperatures of two T₁ minima shift downwards, (2) T₁ versus 1/T curves become broader near each T₁ minimum and (3) T₁ at the right minimum is longer than that at the left minimum for x≤0.19. The experimental result (3) may suggest that more K⁺ ions are substituted for NH₄⁺(I) than for NH₄⁺(II) ions. A single T₁ minimum curve is obtained for x=0.84. This means that only one type of NH₄⁺ ions, NH₄⁺(II), remains at higher concentration of K₂SO₄.

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Effects of hydrostatic pressure on the phase transitions in ferroelectric Ca₂Sr(C₂H₅COO)₆ and Ca₂Pb(C₂H₅COO)₆ were studied by dielectric constant measurements in a temperature range of −100∼+200°C and a pressure range up to about 8.5 kbar. The I–II transition temperatures (8.7°C in the Sr-salt, 60.4°C in the Pb-salt at 1 atm) monotonically increase with increasing pressure with initial slopes of 19.7 deg kbar⁻¹ for the Sr-salt and 23.4 deg kbar⁻¹ for the Pb-salt, respectively. The II–III transition temperatures (−173°C in the Sr-salt, −88°C in the Pb-salt at 1 atm) increase with increasing pressure, and the first order II–III phase boundaries terminate at critical points of p_crit=3.35 kbar; T_crit=−35°C in the Sr-salt, and p_crit=1.73 kbar; T_crit=−41°C in the Pb-salt, respectively. A sharp maximum of low frequency dielectric constant was found at the critical point of the Pb-salt.

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Optical activity in the screw type structure is studied by calculating off-diagonal part of spin wave susceptibility making use of the theory of linear response.
The results show that optical activity is derived from two kinds of processes related to both one and two magnon. The analysis of optical activity in the screw type structure makes it possible to specify the sign of the exchange constant through the dispersion relations of spin waves.

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The line shape of the LO-phonon assisted cyclotron resonance (PACR) is calculated on the basis of the theory of Enck et al. Measured values of the resonance magnetic field, full width and peak height of PACR in n-InSb are compared with theory. The results show that the strong coupling between Landau levels through LO-phonon (polaron pinning) gives rise to the anomalous line broadening and peak shift.

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Low order electron diffraction intensity is sensitive to the electron state of a crystal. Based on this fact, an electron diffraction study has been made to determine the electron state of the ferrimagnetic interstitial compound Mn₄N by measuring its low order superstructure reflection intensities from polycrystalline films. The result shows that the electron state can be expressed as Mn⁰(Mn^+0.2)₃N^−0.6. X-ray crystal structure factors obtained from the observed electron diffraction crystal structure factors not only coincide well with those determined by X-ray diffraction, but also have an accuracy of about one order higher. Electrons filling the 3d band of Mn₄N are also investigated according to the above electron state model and the magnetic moment distribution in the crystal. Hund’s rule is shown not to hold for Mn₄N. Some discussions are made about the electron state determined by the diffraction method.

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The atomic screening constants appropriate for the modified Slater orbitals are proposed. These constants are chosen under the orthogonality conditions ∫₀^∞P_nl(r)P_n′l(r)dr=0, where P_nl(r) is the radial part of the wave function ψ_nlm=N_nlY_lm(θ,\varphi)r⁻¹P_nl(r) and is assumed to be the minimal combination of the Slater type orbitals;
(Remark: Graphics omitted.).
Some of the ground state orbitals are compared with other different approximations.

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A computational method is proposed to obtain rotational transition probabilities in collisions between two diatomic molecules. With the use of the effective potential method of Rabitz and the exponential approximation, the semiclassical coupled equations are solved without invoking any perturbational technique. The collision trajectory is determined in the classical modified-wave-number approximation. The method can treat systems of strong interactions and provide probabilities for transitions even with a multi-quantum jump. A simultaneous transition in the rotational states of both molecules, i.e., the rotational-rotational energy transfer, is taken into account. An application to the system, N₂+N₂, is described in detail.

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Velocities of ultrasound waves in helium, argon, and nitrogen gases have been measured at 25°C under high pressure up to 15 KB for helium and nitrogen, and 13 KB for argon where it solidifies, using a single-pulse ultrasonic technique. Lead zirconate titanate ceramics with fundamental frequencies of 1 and 2 MHz are used as transducers. The observed velocities of ultrasound waves are in good agreement with the previous data. The ratios of specific heats are also calculated.

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The magnetohydrodynamic (MHD) equations for the interaction of shock-induced plasma flows with transverse magnetic fields are solved numerically by taking into account the radiative energy loss; real gas effects such as variable degrees of ionization are also considered. The one-dimensional flow is assumed. The results are compared with experimental data obtained with an arc-driven shock tube whose test section is similar to the MHD generator of the Faraday type. The continuum radiation intensity is measured as a function of time. Good agreement is obtained in the time histories of the calculated and measured continuum radiation intensities at the position where the flow is one-dimensional.

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When a straight channel formed by two parallel porous walls, through which liquid is flowing under a constant pressure gradient, is rotated about an axis perpendicular to the walls, secondary motion is set up. The secondary motion is analysed in detail for constant angular velocity Ω′ and the suction Reynolds number β. The flow depends on the Taylor’s number α, pressure gradient P and the suction Reynolds number. In a rapidly rotating system such that (P⁄α²) is finite, the secondary flow is confined to regions of order [α+(β⁄2)]⁻¹ and a boundary layer is formed in the vicinity of both the walls. A method for setting up an experiment to test the theoretical conclusions of the paper is suggested.

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By using nonlinear perturbation method a time-dependent equation is derived which governs internal waves in stratified fluids of great depth. The resultant equation takes the following form:
(Remark: Graphics omitted.),
where (Remark: Graphics omitted.) denotes Hilbert transform of u. The equation admits exact solutions representing ‘algebraic’ solitary waves and nonlinear periodic waves, both of which were first obtained by Benjamin.
It is found that the equation yields the time-invariant quantities such as ∫_−∞^∞udx, ∫_−∞^∞u²dx, (Remark: Graphics omitted.) and ∂∫_−∞^∞xudx⁄∂t. Based upon these conservation laws, break up of an initial Lorentzian pulse into two ‘algebraic’ solitary waves is discussed to predict the amplitude of emergent ‘algebraic’ solitary waves.

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The resonant four-wave interaction is studied for a nonlinear two-dimensional Klein-Gordon system. A set of dynamical equations describing the slowly varying amplitudes is first derived for a spatially homogeneous case. Exact solutions to the set of equations are then obtained. They are classified into the following four types: (i) periodic solutions, (ii-1) solitary pulse solutions, (ii-2) a phase jump and three solitary pulse solutions, (iii) shock-like solutions. Some of these solutions, especially the type (iii) solutions, are quite different from those of the well-known nonlinear three-wave interaction.

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A study is made of steady homogeneous isotropic turbulence, on the basis of Edwards’ Fokker-Planck method introducing the concepts of turbulent diffusion and turbulent viscosity (S.F. Edwards: J. Fluid Mech. 18 (1964) 239). In this paper, the renormalized vertex is introduced in addition to them. The Liouville equation for the probability distribution function is solved, under the requirement that in the perturbative solution, only the leading two terms up to the first order of the renormalized vertex contribute to the second- and third-order velocity correlations. As the result simultaneous nonlinear integral equations are obtained for the turbulent diffusion and viscosity coefficient, and the renormalized vertex. It is shown that these equations are not expected to give Kolmogoroff’s spectrum.

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Stratford’s theory for the prediction of separation of the turbulent boundary layer is modified so that it may be applicable to the critical flow, in which occurs a separation bubble followed by a turbulent reattachment. Calculations are based on the assumptions that (i) transition occurs at the laminar separation position which is predicted by the Stratford-Curle formula, and (ii) the velocity profile at the transition point is that of a turbulent zero-pressure-gradient flow which is taken as the “comparison” profile. The accuracy of the method is tested for experimental pressure distributions around a circular and an elliptical cylinder. It is seen that the theoretical positions of transition are in remarkably good agreement with the experiments, whereas those of turbulent separation (for critical flows) will tend somewhat to precede the experimental ones. An application to the free-streamline flow past a circular cylinder is also presented.

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The bipolar coordinate solution of the two-dimensional Stokes equations is applied to the flow along a plane wall with a projection or a depression. The resultant integral is evaluated by the calculus of residues to give an eigenvalue expansion and the eigenvalues are calculated for various values of the parameter. Special consideration is made for a cylinder inlaid in the wall.

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Three part and generalised three part boundary value problems in potential theories and related problems are considered for the case of an annular spherical cap shaped lamina when the difference between the bounding angles is small. Solutions of the potential problem due to double lamina and the presence of an annular cap shaped crack in an elastic medium under torsion is considered. We also consider disturbance due to an annular spherical cap placed in a flow of an inviscid fluid.

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In proton-nucleus collisions at 200 GeV studied in nuclear emulsion, relativistic particles are found to be emitted in the laboratory backward hemisphere frequently. These backward particles consist of pions and protons of relatively high energy. Emission of backward particles increases rapidly with the mass number of the target nucleus. Backward emission of such high energy particles is difficult to explain by the simple superposition of proton-nucleon elementary interactions.

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The thermal conductivity of nearly ideal one-dimensional antiferromagnet TMMC has been measured in the short range spin correlated region. Anomalously large anisotropy of the conductivity was observed. This anisotropy can not be attributed to the lattice system only, but reasonably be accounted by considering the enhanced contribution from the paramagnetic magnon mode as predicted by Huber.

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The simultaneous measurements of the specific heat and the dielectric constant of NaNO₂ were carried out near T_N. It was revealed that the maximum of the dielectric constant occurs at a temperature 0.07±0.02 K higher than the Néel temperature which was determined from the specific heat data.

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NMR determination of the direction of the magnetic moment in antiferromagnetic V₂O₃ has been made using a single crystal. From the external magnetic field dependence of the MNR frequency and the signal intensity, the magnetic moments are shown to lie on the hexagonal (110) layers making an angle of 71°±3° with the hexagonal c-axis.

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We report the first observation of transient nutations, spin echoes and stimulated echoes associated with two-quantum transition between levels for which single-quantum transition is forbidden. The experiment was made on a multi-level NMR system, ²⁷Al in Al₂O₃ with its c-axis parallel to the static magnetic field H₀, where level spacings were unequal and no state mixing existed. To detect the coherence between levels with Δm=2 the technique of transfer of coherence was used. The equation of motion of the spins was simpler than that usually used in a three-level system.

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Higher harmonics in backscattered laser light from the CO₂ laser produced plasma were investigated. They were in the frequency range of (3⁄2)ω₀ and 2ω₀, when TEA CO₂ laser light of the frequency ω₀ was focused on a carbon target.
The threshold laser intensity of higher harmonics are 5×10¹⁰ W/cm². It coresponded to the threshold of Raman backscattering. One half frequency of the laser light was not observed at the present time.

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Evidences of the Kohn anomaly and the Peierls transition in TTF–TCNQ were found by X-ray scattering experiments. The Kohn anomalies observed at T=293 K and 63 K give the Fermi wave number, k_F, of the one-dimensional electron system as 2k_F=b^*⁄(3.7±0.2), where b^* is the reciprocal lattice vector. At 54 K, the one-dimensional ordering of the lattice deformation due to the Peierls transition was found along the b-axis with the period of b′=(3.7±0.2)b. At 27 K, the three-dimensional ordering was observed giving the new unit cell as a′=4a, b′=3.7b and c′=c.

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