Neutron-diffraction investigation of the intramolecular structure of a water molecule in the liquid phase at high temperatures

Time-of-flight neutron diffraction measurements were carried out on pure liquid water in the high-Q region and at high temperatures between 25 and 200°C. The observed data at high scattering angle (ca. 90°) have been analyzed to determine the intramolecular distances r OD and r DD by solving the problems of the inelasticity corrections. They show no temperature dependence, within experimental error, between 25 and 200°C: r OD = 0·970 ± 0·005 Å and r DD = 1·55 ± 0·01 Å. The conclusion reached in this work is consistent with the results of high frequency Raman scattering. The intramolecular structure of water molecule is unchanged by temperature, but its structure can be changed by ion-water interaction as shown in previous work.