Isao Ichishima

Rotational Isomerism in Chloroacetone

Raman spectra of chloroacetone were measured in the liquid and solid states and in solutions. Infrared absorption spectra of this substance were measured in the gaseous, liquid, and solid states and in solutions. The temperature dependence of the intensity of the Raman lines and of the absorption bands were measured in the liquid state. From the experimental results together with the dipole data it was concluded that chloroacetone exists in two molecular forms in the liquid and gaseous states and in one form in the solid state. The less stable form in the liquid state becomes much more abundant than the other form in the gaseous state. Some considerations on the nature of hindering potential of internal rotation have been made.

Rotational Isomers of Chloroacetyl Chloride, Bromoacetyl Chloride, and Bromoacetyl Bromide

The Raman spectra of chloroacetyl chloride, bromoacetyl chloride, and bromoacetyl bromide have been measured in the solid and liquid states. The infrared absorption spectra of these substances have also been measured in the liquid and the gaseous states. From the experimental results it has been concluded that there are two rotational isomers in the liquid and gaseous states and only one of them persists in the solid state. The temperature dependence of the intensity of the infrared absorption in the gaseous state has also been studied, and the energy difference between these two isomers has been found as 1.0±0.1 kcal/mol for bromoacetyl chloride and 1.9±0.3 kcal/mol for bromoacetyl bromide.The calculation of the normal vibrations and of the product rule has been made for various configurations of rotational isomers, and it has been shown that the more stable form is the trans form (or nearly this one) with regard to the two halogen atoms. The less stable form is considered to have an azimuthal angle betw...

Far infra-red spectrum of hydrazine

Abstract The rotation-vibration spectrum of hydrazine vapour has been measured from 250 to 750 cm−1. The torsional vibration bands arising from the transition of n: 0 → 1, 0 → 2 and 1 → 2 were assigned. The centres of the bands were located at 376·74, 665·9 and 289·5 cm−1, respectively. By the analysis of the fine structure, rotational constants were determined. From these the bond lengths and the bond angles of the molecule were calculated. According to the irregular spacing of the Q-branch near the centre of the band, the asymmetry factor e was estimated to be very small, and the molecule appears to have a right-angle structure.

Infra-red and Raman spectra of dichloroacetyl chloride in relation to rotational isomerism

Abstract Vibration spectra of dichloroacetyl chloride have been measured in the gaseous, liquid and solid states and also in solutions. From the experimental result it was concluded that in the gaseous and liquid states there exist two molecular forms, of which only the more polar form persists in the solid state. The energy difference between these two forms is almost zero in the liquid state and amounts to about 200 cal mole in the gaseous state, the less polar form being more stable. In this form the oxygen atom is in the cis-position with respect to the hydrogen atom. The more polar form is obtained from this form by an internal rotation about the C-C axis by about 90°.

Infrared and Raman Spectra of 1,1,2,2‐Tetrachloroethane; Calculation of Normal Vibrations

Infrared spectra of 1,1,2,2‐tetrachloroethane have been measured in the gaseous, liquid, and solid states and in solutions. Raman spectra of the same substance have been observed in the liquid and solid states. From the experimental results the equilibrium molecular forms of the rotational isomers have been determined. The normal vibrations of the molecule in the trans‐ and gauche‐forms have been calculated as an 8‐body problem, and the assignment of the observed infrared and Raman frequencies in all the states of aggregation has been made.

Internal rotation in 1:2-dichloro-2-methylpropane

Abstract Infra-red spectra of 1:2-dichloro-2-methylpropane have been measured in the gaseous, liquid, and solid states and in various solutions. Raman spectra of this substance have been measured in the liquid and solid states, and in solutions. The normal vibrations of the skeleton of the molecule have been calculated, using a potential function of the Urey-Bradley type. From these results the equilibrium molecular forms of rotational isomers have been determined and their stability in different states has been discussed. The observed infra-red and Raman frequencies have been assigned.

Polarization of the reflected infrared radiation from an echelette grating

Abstract Intensity ratio of the two components of the reflected infrared radiation was measured with the Perkin-Elmer 112G instrument, one component being polarized parallel to the grooves of the grating and the other perpendicular to them. The ratio was found to depend considerably on the direction of the incident beam with respect to the surface of the grating and to be quite different from that obtained in a similar measurement with prism spectrometer.