title: Dielectric spectroscopy of hydrogen bond dynamics and microheterogenity of water + dioxane mixtures.
abstract: Mixtures of water or D2O + 1,4-dioxane (DX) have been studied at 25 degrees C by dielectric relaxation spectroscopy over a wide range of frequencies (0.2 < or = nu/GHz < or = 89) for DX mole fractions 0 < or = x2 < or = 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 H2O molecules in the water-rich regions.
authors.affiliation: Institute of Physical and Theoretical Chemistry, Universität Regensburg, Regensburg, Germany.
authors.forename: Simon
authors.initials: S
authors.lastname: Schrödle
authors.forename: Glenn
authors.initials: G
authors.lastname: Hefter
authors.forename: Richard
authors.initials: R
authors.lastname: Buchner
mesh_terms: D017666:Deuterium Oxide / Q000737:chemistry; D004146:Dioxanes / Q000737:chemistry*; D004574:Electromagnetic Fields; D006860:Hydrogen Bonding; D008956:Models, Chemical; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000379:methods; D014867:Water / Q000737:chemistry*
chemical_list: D004146:Dioxanes; D014867:Water; D017666:Deuterium Oxide; C025223:1,4-dioxane