Structural studies of a water/dioxane mixture by neutron diffraction with hydrogen/deuterium substitution

Neutron diffraction measurements have been made of a 0.167 mol fraction mixture of deuterated 1,4 dioxane in water. Measurements were made for four different isotopic compositions of the H2O/D2O water to separate the partial structure factors of the hydrogen atoms in the water molecule. A MCGR technique was used to analyse the data. The results show strong spatial correlations arising from the hydrogen bond network for the water which have similar features to those observed in the pure aqueous phase. It appears that the dioxane molecule is incorporated into the water network with little distortion of the local correlations. A large small-angle scattering signal was observed at low Q-values which varied according to the H/D contrast. This feature can be fitted by the MCGR routine and may relate to some ordering on a mesoscopic scale. Further studies are in progress.