Far-infrared study of reorientational motion in diphenyl ether

Abstract

The far-infrared 20–200 cm^–1 absorption spectrum of liquid diphenyl ether is presented and analysed using a three-parameter approximant of the Mori continued fraction. Two of the parameters are determined by knowledge of the relaxation time τ_D and the volume of rotation V of the molecule. The analytic spectra represent the experimental data well only when coupled inter- and intra-molecular reorientations are allowed. This suggests that the anomalously small relaxation time arises primarily from coupled reorientation of a body-fixed dipole vector and not by mesomeric moment inversion.

The solution spectra of diphenyl sulphide and dibenzofuran are also shown to be ameanable to this same powerful analytic technique.