Microwave Absorption and Molecular Structure in Liquids. LVI. Dielectric Behavior of Water and Heavy Water in Dioxane

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Abstract
The dielectric constants and losses of seven water—dioxane mixtures and six heavy‐water—dioxane mixtures ranging in concentration from 5 to 58 mole % of water have been measured at wavelengths from 0.44 to 10.0 cm. The results are interpreted in terms of two partly superimposed noninteracting Debye dispersions. The high‐frequency dispersion region for the water—dioxane mixtures corresponds to a relaxation time 4×10—12 sec, which is concentration independent, while the low‐frequency dispersion region corresponds to a relaxation time which is concentration dependent and rises to a maximum at about 70 to 80 mole % water. The relaxation time 5.6×10—12 sec associated with the high‐frequency dispersion region of the heavy‐water—dioxane mixtures differs from the corresponding relaxation time for water—dioxane mixtures by a factor of (½)½. The low‐frequency concentration‐dependent relaxation time was found to be about 1.2 to 1.5 times greater than the corresponding relaxation time of the water—dioxane system. The high‐frequency dispersion region is attributed either to the rotation of the OH (or OD) group about its hydrogen (or deuterium) bond or to over‐all molecular relaxation. The low‐frequency dispersion is attributed to the partial breaking and reforming of the hydrogen (or deuterium) bond. The rotational mechanism becomes a molecular libration in the extrapolating to pure water and contributes to the large atomic polarization observed.