Interpretation of the microwave and far infra-red absorption of some dipolar liquids in terms of librational and relaxational motion

Abstract

The microwave and far infra-red spectra of 1,2-dibromo-1,1-dichloroethane; 1,2-dibromo-2-methylpropane; 1-iodo-2-methylpropane; and 1-iodo-3-methylbutane obtained recently by Moisan are discussed in terms of two models of librational and relaxational modes of absorption in dipolar liquids. An acceptable fit to the observed data is obtained on the assumption of a hexagonal symmetry for the planar disposition of the potential wells. The barrier heights to libration suggested by this phenomenological approach are, as expected, greater than results for molecules of enhanced symmetry which form rotator phases.