Neutron-diffraction studies of the structure of water

Measurements of the differential scattering cross section for thermal neutrons by heavy water (D20) have been made for a temperature range 11 to 790C. A systematic change in the diffraction pattern is observed and the position of the first peak is found to vary linearly with temperature. It is shown that the difference functions corresponding to the temperature changes are insensitive to the experimental and analytic corrections which are applied to the cross-section data and may be used to give information of the structural changes in the liquid by use of Fourier transform methods. The results are consistent with information derived from X-ray diffraction data and show that hydrogen-bond breaking plays an important role in the structural changes which occur as the temperature is raised. (author)