The Interaction Energy of an Ion Pair with Overlapping Hydration Shells. I. A Truncated Spheres Model

Abstract

The energy of interaction of two univalent ions of opposite charge with overlapping hydration shells and in an aqueous medium is discussed in terms of a truncated spherical cavity model. The general trend of the effective dielectric constant considered as a function of the separation between the ion centres is found to be in agreement with some earlier results on a spheroidal cavity model. The present investigation has the advantage that the boundary of the ion pair , varies continuously with separation and hence that no matching of a two· sphere model onto a spherical cavity model is required. It is found that the effective dielectric constant has a maxinum value at very small ion overlap.