Abstract
The far-infrared absorption coefficient of phenol, thiophenol and the analogous halobenzenes in a polyethylene matrix have been investigated using a far-infrared laser. The absorptions are interpreted in terms of an asymmetric double well, for which the theory is derived, and Debye relaxation theory. Phenol is found to be more strongly coupled to the matrix than is thiophenol. For both molecules the matrix modification of the barrier to internal rotation is far greater than any asymmetry introduced.