| Abstract
| - A systematic study of the dielectric relaxation spectra of aqueous solutions of NaBr, NaI, NaNO3, NaClO4,and NaSCN has been made over a wide range of frequencies (0.2 ≤ ν/GHz ≤ 89) and solute concentrations(0.05 ≤ c/M ≤ 1.5) at 25 °C. The spectra could be adequately described by a single Cole−Cole (CC) process,symmetrically broadened relative to that of pure water. However, similar quality fits were also obtained witha three-Debye-process (3D) model consisting of a small ion-pair contribution at lower frequencies and twosolvent relaxations at higher frequencies. Assuming the ions to be solvent separated, the 3D model providedestimates of their association constants and their rate constants for formation and dissociation. The bulk waterrelaxation times obtained from both models showed almost no dependence on the nature of the anion.Nevertheless, there were subtle differences in the concentration dependences of the relaxation times whichcorrelated with some, but not all, of the anion properties that are believed to be relevant for explaining theanionic Hofmeister series.
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