TRACER DIFFUSION OF NONSPHERICAL COLLOIDAL PARTICLES

A general theory is presented to describe the effects of the direct in teractions of a labeled nonspherical colloidal particle with other (sp herical or nonspherical) particles diffusing around it, on the transla tional and rotational tracer-diffusion properties of the former. Appro ximate, but general expressions are derived for these dynamic properti es in terms of static structural properties of the system, in the gene ric case in which the particles with which the nonspherical tracer int eracts are spherical. The specific use of these results is illustrated with the calculation of the rotational diffusion coefficient of a Bro wnian dipole that interacts with a Brownian one-component plasma, and of an ellipsoidal polyion interacting with its own electrical double l ayer.