Dielectric Spectroscopy of Hydrogen Bond Dynamics and Microheterogenity of Water + Dioxane Mixtures

Abstract

Mixts. of water or D2O + 1,4-dioxane (DX) have been studied at 25 °C by dielec. relaxation spectroscopy over a wide range of frequencies (0.2 ≤ ν/GHz ≤ 89) for DX mole fractions 0 ≤ x2 ≤ 0.67. The spectra were best fitted by the sum of two Debye terms. The slower process was assigned to the cooperative relaxation of the hydrogen-bond network of water, whereas the faster mode reflects the dynamics of H2O mols. in a DX-rich environment. Anal. of the relaxation parameters revealed a largely microheterogeneous structure of the mixts. The marked slowing-down of the cooperative mode on addn. of DX is ascribed to the redn. of available H-bond acceptor sites and geometrical constraints on the H2O mols. in the water-rich regions.