ROTATIONAL BROWNIAN-MOTION AND DIELECTRIC-RELAXATION OF POLAR-MOLECULES SUBJECTED TO A CONSTANT BIAS FIELD - EXACT SOLUTION

The longitudinal and transverse components of the complex dielectric s usceptibility tensor and dielectric correlation times are calculated e xactly for a system of noninteracting polar molecules placed in a cons tant external electric field. The calculations are carried out in the context of the rotational diffusion model. The theoretical results are compared with experimental data on both the magnetic relaxation of co lloidal suspensions of single domain ferromagnetic particles (ferroflu ids) and the dielectric relaxation of dilute solutions of polar macrom olecules in a bias field. There is good agreement with the experimenta l data on both of these systems. It is shown that previous analytic re sults for the correlation time based on the effective eigenvalue metho d are in general an acceptable approximation to the exact solutions.