Dielectric relaxation of aqueous NaF and KF solutions

Dielectric relaxation experiments in the frequency range 0.45 ⩽ν/GHz ⩽ 89 are presented for aqueous solutions of NaF and KF at 25 °C. The complex permittivity spectra reveal two dispersion steps attributed to the cooperative relaxation of the solvent, τs≈ 8 ps, and to the formation of a small quantity of predominantly solvent separated ion pairs, τIP≈ 100 ps. The dielectric decrement observed for the solvent permittivity is discussed in terms of kinetic depolarization and dielectric saturation; ‘effective’ solvation numbers are estimated.