Local Self-motion of Water through Van Hove Function...

We show that the self-part of the Van Hove Functionthe correlation function describing the dynamics of a single moleculeof water can be determined through a high-resolution inelastic X-ray scattering experiment. The measurement of inelastic X-ray scattering up to 10 -1 makes it possible to convert the inelastic X-ray scattering spectra into the Van Hove function, and its self-part is extracted from the short-range correlations. The diffusivity estimated from the short-range dynamics of water molecules is different from the long-range diffusivity measured by other methods. This approach using the experimentally determined self-part of the Van Hove function will be useful to the study of the local dynamics of atoms and molecules in liquids.