Masao Kimura

Molecular structure of benzene

Abstract The molecular structure of benzene has been determined by combining the average distances obtained by the present electron diffraction study and the moments of inertia reported by Cabana et al. The following thermal average bond distances have been determined: r g (C-C) = 1.399 ± 0.001 A and r g (C-H) = 1.101 ± 0.005 A. The uncertainties represent the estimated limits of error. The C-H distance of this molecule is similar to vinyl C-H distances.

Unit for the Precise Measurement of Electron Diffraction Intensities by Gas Molecules

An apparatus for the precise measurement of electron intensity diffracted from gas molecules has been constructed. Care has been taken to define camera distances precisely by installing a table, to which the nozzle and the photographic plate can be fixed firmly, and to eliminate extraneous scattering by designing a suitable electron-optical system and by inserting a brass ring with a folded wall covered with soot into the sector race. A critical examination by the use of carbon dioxide has shown that the structure can be determined with the accuracy of one thousandth of an angstrom with the present apparatus.

Atomic Scattering Factors for Electrons as Calculated by the Partial‐Waves Method

Complex atomic scattering factors were calculated from the partial‐wave scattering theory using the Hartree—Fock atomic potentials for the atoms H to Kr and the Thomas—Fermi—Dirac atomic potential for the atoms Kr to Cm. The partial phase shifts were approximated in terms of modified Bessel functions of the second kind.

Molecular structure of dimethylether as determined by a joint analysis of gas electron diffraction and microwave spectroscopic data

Abstract The molecular structure of gaseous dimethylether has been investigated by a joint analysis of the electron diffraction data and the moments of inertia reported by Blukis et al. The structural parameters were determined to be as follows: r g (Cue5f8O) = 1.415 ± 0.001 A, r g (Cue5f8H) av = 1.118 ± 0.002 A, φ av (COC) = 111.8 ± 0.2° φ av (HCH) = 109.2 ± 0.2°, θ(tilt angle of the methyl groups) = 3.6 ± 1.7° and τ(torsional angle of the methyl groups) = 2 ± 11°. The uncertainties represent the limits of error. With the aid of an ab initio geometry optimization, it has been concluded that dimethylether has C 2v symmetry and that each of the methyl groups staggers the opposite C ue5f8O bond.

Band shapes of Fermi resonance spectra

Fermi resonance is treated as an intramolecular energy transfer from one vibrational mode to another. The equation of motion for the vibrational correlation function is solved by assuming that each mode of a molecule has two energy levels. The power spectrum, given as the Laplace transform of the correlation function, is not generally described by the overlap of two symmetric bands. Various aspects of the spectrum are discussed.

Band shapes and moment analysis of the far-infrared absorptions of dipolar molecules in solutions

Abstract The moment analyses were performed on the far-infrared absorption bands of CH 3 CN, CHCl 3 , CH 2 Cl 2 , and their deuterated compounds dissolved in nonpolar solvents. The values of torque acting on the solute molecules were estimated from the fourth moments. The band profiles were simulated by means of the continued-fraction representation of the time correlation function by Mori, using the moment values obtained. The third order long-time approximation of the correlation function yields essentially good simulations. The effective rotation angles of molecules between collisions were estimated from the first positive-to-negative turning points of the memory functions. The solvent effects on the torque and the rotation angle were consistent with each other.

The force constants of tin tetrachloride

Abstract The force constants of a general quadratic potential energy for tin tetrachloride were determined by using the mean-square amplitudes of vibration observed by electron diffraction and the vibrational frequencies. Furthermore, the most probable force field data were proposed by combining the results obtained from the mean-square amplitudes with those from the Coriolis coupling constant. It was shown that: (1) The use of the relative Raman intensities as additional information yielded a reasonable force field; (2) No approximate methods could be applied satisfactorily to the determination of the force constants.

Molecular structure of DI-t-butylsulphide as determined by gas electron diffraction

Abstract The molecular structure of di-t-butylsulphide has been investigated by gas electron diffraction. The molecule has C2 symmetry with the following bond lengths (rg) and angles (rα): r(Sue5f8C)=1.854(5) A, r(Cue5f8C)=1.539(3) A, r(Cue5f8H)=1.127(4)A, ∠CSC=113.2(12)°, ∠CCC=109.6(5)°, ∠CCH=111.2(11)°. The torsional displacement of t-butyl groups from the staggered conformation is 12(8)° and the tilt angle of t-butyl groups is 7(2)°. The result is in close agreement with a molecular mechanics calculation. The values of rg(Sue5f8C) and ∠CSC are greater by about 0.04 A and 14° respectively than the corresponding values for dimethylsulphide and ethylmethylsulphide, reflecting steric hindrance between the t-butyl groups.

Far-infrared absorption intensity of hydrogen chloride dissolved in carbon tetrachloride

Abstract The integrated intensity of the far-infrared absorption of hydrogen chloride dissolved in carbon tetrachloride has been measured. It agrees well with a value calculated from Gordons sum rule, and indicates no appreciable collision-induced absorption.

Molecular structure and conformation of diisopropylamine studied by gas electron diffraction combined with vibrational spectroscopy and molecular mechanics

Abstract The molecular structure and conformation of diisopropylamine have been determined by gas electron diffraction with the aid of vibrational spectroscopy and molecular mechanics calculations. Only one conformer with the skeletal geometry of C2 symmetry has been detected. The dihedral angle, CNCH, has been determined to be 52(4)°. The difference between the NCC angles at the gauche and trans positions with respect to the opposite Nue5f8C bond is 2.4°. The CNC bond angle, 120.1(10)°, and the Cue5f8N bond length, 1.470(4) A, are 8.3° and 0.014 A larger than the corresponding values of dimethylamine respectively