The lifetime of a librational state as a measure of the elasticity of the spatial H-bond network

The elasticity parameter M-w of the spatial H-bond network (SN) is defined and calculated as the ratio of the librational-state lifetime to the mean librational period. Wide band dielectric spectra, observed in a number of aqueous systems, are employed as the basis of the theoretical estimation of M-w, where the index w refers to water molecules. In the case of liquid water, the parameter M-w is of the order of 10; M-w sharply decreases with the temperature T increase because of the weakening of the SN. In the case of a nonelectrolyte aqueous solution, viz. dimethyl sulfoxide (DMSO)-H2O, M-w increases with the rise of DMSO concentration. In the cases of NaCl-water and KCl-water solutions, the elasticity parameter M-w increases or decreases, respectively, when the concentration of electrolytes rises. This theoretical result corresponds to the sign (positive or negative) of hydration. (C) 1999 Elsevier Science B.V. All rights reserved.