ORIENTATIONAL RELAXATION IN HYDROGEN-BONDED SYSTEMS - AQUEOUS-SOLUTIONS OF ELECTROLYTES

A model ol the rotational motion of water molecules within ion hydrati on sheaths is proposed in the present paper. This model is based on th e concept of a 'boundary' ion, according to which the parameters of th e structural surroundings, as well as the translational, rotational an d librational motions of water molecules within the first sphere, are the same as those for water molecules in water. The wide-band absorpti on spectra, alpha(nu) (0 < nu/cm-1 < 400), and the complex dielectric permittivity spectrum measured for the concentrated electrolyte soluti ons, are described on the basis of the model proposed in this paper. I t is shown that the confined rotator/extended diffusion (CR/ED) model, which has been advanced previously for liquid water, is applicable fo r spectral calculations of the electrolyte solutions studied in the pr esent paper. The typical characteristics of ions having hydrophilic an d hydrophobic hydration, as well as the distinctions between the hydra tion sheaths of ions with negative and positive hydrations, are discus sed. A new method is proposed to study the molecular nature of these p henomena at the level of elementary processes. The complex dielectric permittivity of the concentrated LiCl, NaCl, Nal, KCl and KBr solution s has been measured in the range 7-25 GHz at 25-degrees-C. For electro lyte solutions, the wide band (0 less-than-or-equal-to nu/cm-1 less-th an-or-equal-to 1000) dielectric spectra and the parameters of the prop osed model are calculated.