The structure of the water molecule in liquid water

The slow neutron scattering measurements of Walford, Clarke and Dore for liquid heavy water at 21°C for incident neutron wavelengths of 0·694 Å and 0·347 Å [7] have been reinterpreted using a sophisticated correction for recoil and detector effects [10] for the molecular contribution to the scattering cross-section. For momentum transfer greater than 6 Å-1 the liquid structure contribution is negligible and a very good agreement between theory and experiment is obtained. It is concluded that the intramolecular oxygen nucleus-deuteron distance is 0·983±0·008 Å, and that the deuteron-deuteron distance is 1·55±0·02 Å. This molecular structure is nearer to that of the molecule in the vapour than that in ice I for the conventional interpretation for ice I. It is concluded that there is an environmental effect on the molecular internuclear distances at most of order 0·01 Å for the molecule in the orthobaric liquid near the triple point.