X-ray diffraction and structure of water

With the help of X-ray diffraction, liquid water at 25°C has been studied. The results agree fairly well with previous work, including the work of van Panthaleon van Eck, Mendel & Boog (1957-1962). The radial distribution function obtained is in accordance with an irregular network model, resembling ice I and the high pressure modifications, ice II, ice III, ice V and ice VI. Unlike the situation in the ice structures, in water a fraction of the hydrogen bonds are broken and all hydrogen bonds have approximately the same chance of being broken. Accordingly, each molecule is not surrounded by 4 hydrogen-bonded neighbours but by a somewhat smaller number, probably 3.2 (on average); moreover, there appear to be 4.6 non-bonded neighbours at a distance of less than 4 Å from the reference molecule.