Tracer diffusion of nonspherical colloidal particles

A general theory is presented to describe the effects of the direct interactions of a labeled nonspherical colloidal particle with other (spherical or nonspherical) particles diffusing around it, on the translational and rotational tracer-diffusion properties of the former. Approximate, but general expressions are derived for these dynamic properties in terms of static structural properties of the system, in the generic case in which the particles with which the nonspherical tracer interacts are spherical. The specific use of these results is illustrated with the calculation of the rotational diffusion coefficient of a Brownian dipole that interacts with a Brownian one-component plasma, and of an ellipsoidal polyion interacting with its own electrical double layer.