Molecular theory of solvated ion dynamics. III. The kinetic dielectric decrement

A microscopic theory of the kinetic dielectric decrement in ionic solutions is developed. The theory clarifies the physical origin of the effect, showing that it is analogous to the electrophoretic effect, and corrects a violation of the reciprocity relations in the original continuum treatment of Hubbard and Onsager. We discuss the concept of the dielectric constant of an electrolyte solution. Calculations indicate that there are specific ion effects, in contrast with the universal behavior predicted by the continuum theory. A critical comparison with present experimental measurements is made.