Kazutoshi Tanabe

Correction of finite slit width effects on Raman line widths

Abstract An equation is derived for the correction of the finite slit width effect on line widths of Lorentzian Raman lines. It holds for up to S/δa = 0.7, more applicable than those proposed previously. A method is also proposed for obtaining the true isotropic line width from observed parallel and perpendicular polarized spectra.

Calculation of infrared band intensities and determination of energy differences of rotational isomers of 1,2-dichloro-, 1,2-dibromo- and 1-chloro-2-bromoethane

Abstract Infrared absorption intensities of fundamental bands of 1,2-dichloro-, 1,2-dibromo- and 1-chloro-2-bromoethane have been measured in the vapor phase and in the pure liquid phase. Using the least squares method, intensity data have been interpreted in terms of the least number of common intensity parameters including the population ratios between the rotational isomers of these molecules. By the determined values of the population ratios, energy differences between the rotational isomers have been evaluated, and the values have been compared with those obtained using the temperature variation method.

Calculation of infrared band intensities of various chlorinated methanes

Abstract Infrared band intensities of three molecular species CHCl 3 , CDCl 3 and CCl 4 , were measured in the vapour phase and the band intensity data of thirteen kinds of various chlorinated methanes, from methane to carbon tetrachloride, have been interpreted by means of as few as possible common intensity parameters. The parameters have been determined by using the least squares method from the observed data on the basis of the valence-optical theory. As a result, it has been proved that for almost all electro-optical parameters, it is possible to determine values which are commonly applicable to all chlorinated methane molecules, but for μ CH and ∂μ CH / ∂ r CH , it is not possible to find commonly applicable values.

Vibrational frequencies, infrared absorption intensities and energy differences between rotational isomers of propyl halides

Abstract Infrared absorption intensities of fundamental bands of propyl halides n -C 3 H 7 Cl, n -C 3 H 7 Br and n -C 3 H 7 I were measured in the pure liquid state. In order to obtain L matrix data necessary for the intensity computation, normal frequencies of the rotational isomers were calculated, and LSFF force constants were determined by the least squares method so as to attain the best fit between the observed and calculated frequencies. By applying the absolute intensity method, energy differences between the rotational isomers were evaluated, which are in quite good agreement with values obtained by the temperature variation method.

Calculation of infrared band intensities of methylene chloride in vapour and liquid phases

Abstract Infrared band intensities of three isotopic species of methylene chloride have been measured in the vapour phase and in dilute solution, and the results obtained for each phase have been interpreted on the basis of the valence-optical theory. The eleven intensity parameters determining the band intensities of these species have been obtained using the method of least squares from the observed intensities, and those parameters estimated for each phase have been compared in relation to the observed spectral changes.

Determination of energy differences between rotational isomers of chloroacetyl chloride, bromoacetyl bromide and dichloroacetyl chloride by the absolute infrared intensity method

Abstract In order to determine the dihedral angle of the gauche isomer of CH 2 ClCOCl, normal frequencies and band intensities have been calculated at various assumed rotational angles of the gauche form. It has been shown by these calculations that the most probable value of the dihedral angle is about 105°. By applying the “absolute intensity method” and using the observed intensities of CH 2 C1COC1 and CH 2 BrCOBr measured in solution, the energy differences between, the rotational isomers of these molecules have been evaluated. The “direct intensity ratio method” has also been proposed as a simplified method to obtain the energy difference, and its applicability has been discussed. The energy differences of CH 2 ClCOCl, CH 2 BrCOBr and CHCl 2 COCl determined by these two methods have been compared with those determined previously by the temperature variation method.

Raman linewidth study of hydration structure of t-butanol in aqueous solution

Abstract The isotropic Raman linewidth of t-butanol at 753 cm −1 has been measured in aqueous solution and in cyclohexane solution, and the concentration dependence of the linewidths in aqueous solution has been interpreted in terms of a model where the extent of the formation of hydrogen bonding is estimated from the partial molar volume of t-butanol.

Comparative study of Raman and i.r. band widths of acetonitrile

Abstract Raman and i.r. band widths of all the vibrational bands of acetonitrile, CH 3 CN and CD 3 CN, have been measured in the pure liquid and in solutions of isotopic compounds. Widths arising from the vibrational relaxation, reorientational relaxation and resonance energy transfer have been separated on the basis of the current theories on vibrational band widths. The vibrational relaxation widths estimated for i.r. a 1 bands agree well with the observed isotropic Raman widths. Acceptable values of the rotational diffusion constants have been obtained from the band width data.

Vibrational frequencies, infrared absorption intensities and energy difference of rotational isomers of 1,2-diiodoethane

Abstract Infrared absorption and Raman spectra of 1,2-diiodoethane CH 2 ICH 2 I have been observed in solution and in solid phase, and observed fundamental bands have been assigned. Infrared absorption intensifies have been measured in carbon disulfide solution, and by using the absolute intensity method, the energy difference between the rotational isomers has been obtained as 1·38 ± 0·10 (kcal/mol). It is in quite a good agreement with the value obtained here by using the temperature variation technique. In addition, the normal frequencies and the absolute i.r. absorption intensities have been computed for various assumed dihedral angles for the gauche isomer, and the angle giving the best fit between the observed and computed values has been determined as 85° ± 5°.

Vibrational assignment, infrared absorption intensities, gauche dihedral angle and energy difference between rotational isomers of chloroacetone

Abstract Infrared absorption intensities of fundamental bands of chloroacetone CH3COCH2Cl have been measured in carbon disulphide solution, and intensity data have been analysed to determine the energy difference between the rotational isomers by applying the absolute intensity method. The value determined for the energy difference is in good agreement with that obtained by the temperature variation method. Further, in order to determine the dihedral angle of the gauche isomer, normal frequencies and absolute band intensities have been computed for various rotational angles and compared with observed values. As a result, the gauche dihedral angle has been determined as 150° ± 10°, which is in good agreement with that obtained by previous authors.