Raman Effect, Infrahyphen;Red Absorption, Dielectric Constant, and Electron Diffraction in Relation to Internal Rotation

摘要

The relative intensities of Raman lines of 1,2‐dichloroethane were determined in the gaseous state as well as in the liquid state. The result combined with that of the dipole measurement in the gaseous state enabled us to determine the equilibrium isomeric ratio of thetrans‐ and the gauche molecules, which was in good agreement with that obtained from the absorption measurement of infra‐red spectra. This ratio could also explain satisfactorily the result of an electron diffraction experiment made by us for the vapor of 1,2‐dichloroethane. The statistical entropy of dihalogenoethanes was calculated from the molecular data and was compared with the third law entropy obtained from the thermal measurement. The frequencies of torsional oscillation about the C&sngbnd;C bond as axis were determined by the difference method and were found to be in agreement with the lowest frequencies of the observed Raman spectra.