Co-ordination of water molecules in isotopic mixtures

The essential question of whether the interactions within liquid water may best be described by either the continuum or the micro domain model has for some time been a matter of some debate within the scientific community. We studied isotopic exchange in H2O/D2O mixtures by the inspection of IR spectra, and found that it depends strongly on the correlation between an individual molecule and its environment. It is further found that in such mixtures a certain proportion of the water molecules is not involved in the mixing process at all. The physical properties of these molecules determine the behaviour of interfacial water that is often described in the biological literature.