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 l ibrational period. Wide band dielectric spectra, observed in a number of aq ueous 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 s harply decreases with the temperature T increase because of the weakening o f the SN. In the case of a nonelectrolyte aqueous solution, viz. dimethyl s ulfoxide (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 electrol ytes rises. This theoretical result corresponds to the sign (positive or ne gative) of hydration. (C) 1999 Elsevier Science B.V. All rights reserved.