Dielectric Spectroscopy of Hydrogen Bond Dynamics
and Microheterogenity of Water+Dioxane Mixtures/B>
S. Schrödle, G. Hefter and R. Buchner ,
J. Phys. Chem. B 111 (2007) 5946-5951. DOI: 10.1021/jp0713413
Abstract
Mixtures of water or D2O + 1,4-dioxane (DX) have been studied at 25 °C by dielectric relaxation spectroscopy over a
wide range of frequencies (0.2 <=n/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 eflects 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 H2O molecules
in the water-rich regions.
|
