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.

Calculations of ionic mobility based on a molecular theory of solvated ion dynamics [J. Chem. Phys. 68, 473 (1978)] are presented. We develop approximation schemes for the equilibrium averages needed in the theory. The results for ions in water are in remarkably good agreement with experiment. The importance of fluid structure, arising from the finite size of solvent molecules, is clearly illustrated.

A method is presented for analyzing experimental data from dielectric relaxation, acoustic relaxation, or other measurements related to a distribution of relaxation times. A consistency test is derived showing whether or not there is any distribution of relaxation times consistent with the data. For consistent data, the analysis then provides bounds on possible interpolations at frequencies between the measured points. Bounds are placed on the cumulative distribution of relaxation times and these bounds are shown to be the most precise attainable on the basis of any given set of experimental data. The analysis is illustrated by application to ’’data’’ generated theoretically from some simple distributions of relaxation times and to some experimental data on dielectric relaxation.

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