Dielectric dispersion in pure polar liquids at very high radio-frequencies II. Relation of experimental results to theory

Abstract

The results of the measurements at centimetre and millimetre wave-lengths on the dielectric properties of water, methyl alcohol and ethyl alcohol described in part I are analyzed. There is no evidence that, for any of these liquids, more than a single relaxation time as a function of temperature is required to account for the dispersion arising from dipole rotation. It is suggested that the observed behaviour of the two alcohols at wave-lengths near to 1 cm, which appears not to conform with the hypothesis of a single relaxation time, is in fact the consequence of resonance absorption. If it is supposed that in dipole rotation and viscous flow the molecules have to surmount potential energy barriers, then it appears that, in each of the liquids examined, the heights of the barriers concerned in the two processes are identical; but the ‘frequency factor’ associated with such processes is much larger for viscous flow than for dipole rotation.