Kerr effect in water + dioxan solutions
The Kerr constants, densities and refractive indices of the water + dioxan mixture over the whole composition range are reported. The molar Kerr constant of H2O extrapolated to infinite dilution in dioxan is found to be ∞(mK2)= 2.3 × 10–27 C2 m5 J–2. The components of the polarizability tensor of H2O are calculated by two approaches, using light scattering data and a bond additivity method. Both give the same result within experimental error: αxx= 1.69 ± 0.04, αyy= 1.9 ± 0.2, αzz= 1.3 ± 0.2 (in units 10–40 C2 m2 J–1), where x is the dipolar axis and z is normal to the molecular plane. The Kerr effect over the whole composition range is interpreted according to a theory of Hasted, proposed for the dielectric polarization of organic + aqueous mixtures. We find that the structure of water increases on addition of dioxan up to xD= 0.2, xD being the mole fraction of dioxan, and then decrease, in apparent contradiction to the results from dielectric polarization which indicate a monotonic decrease in the structure of the water + dioxan mixture.