Dielectric Relaxation of Molecules Containing Rotating Polar Groups

Abstract

DEBYE‘S theory of dielectric relaxation has been extended to molecules consisting of two similar polar groups, which cannot rotate freely relatively to one another about their common rotational axis owing to their mutual potential energy. As a result the mean dipole moment of the molecule in the field F = F₀ exp ÎÏt can be expressed by a sum of terms of Debye‘s type, namely, C_n/(1 + ÎÏÏ_n). The determination of the relaxation times Ï_n and of the C_n‘s leads to the problem of the characteristic values and functions of a differential equation of Hill‘s type, the explicit form of which is determined by the potential function V(φ), where φ is the azimuthal angle between the dipole moments of the groups.