Dielectric spectroscopy of hydrogen bond dynamics and microheterogenity of water + dioxane mixtures

Schrödle, S., Hefter, G. and Buchner, R. (2007) Dielectric spectroscopy of hydrogen bond dynamics and microheterogenity of water + dioxane mixtures. Journal of Physical Chemistry B, 111 (21). pp. 5946-5955.

Abstract

Mixtures of water or D20 + 1,4-dioxane (DX) have been studied at 25°C by dielectric relaxation spectroscopy over a wide range of frequencies (0.2 ≤ v/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 molecules in a DX-rich environment. Analysis of the relaxation parameters revealed a largely microheterogeneous structure of the mixtures. The marked slowing-down of the cooperative mode on addition of DX is ascribed to the reduction of available H-bond acceptor sites and geometrical constraints on the H 2O molecules in the waterrich regions.