Character of absorption in far infra-red by polar molecules in liquid state

Abstract

The use of the Fourier spectrometer has been extended down to 2 cm^–1 and the results of a study of the absorption and dispersion in the liquid and dissolved states of selected polar molecules (methyl chloroform CH₃CCl₃; chlorobenzene C₆H₅Cl; benzonitrile C₆H₅CN; tolune C₆H₅CH₃) from this wave number to beyond 100 cm^–1 are reported. It is concluded that the available representations (Record, Powles) of the decay of the dipole relaxation (Debye) absorption due to the inertia factor are inadequate. The further distinct absorption of polar liquids predicted by Poley has been observed for each of the liquids studied. Systematic evaluation of the nature of these absorptions has shown intense features of considerable breadth located in the wave number range 30 to 80 cm^–1.

Observed data are :[graphic omitted]

This (Poley) absorption is of intensity proportional to the molar concentration and is apparently independent of the solvent on dilution. The wide significance of these data is discussed.