Quasi-elastic neutron scattering was used to investigate the diffusion dynamics of hydration water on the surface of rutile nanopowder. The dynamics measurements utilizing two inelastic instruments, a back-scattering spectrometer and a disk chopper spectrometer, probed the fast, intermediate, and slow motions of the water molecules on the time scale of picoseconds to more than a nanosecond. A model-independent analysis of the data collected at each value of the scattering momentum transfer was used to investigate the temperature dependence of several diffusion components. All of the probed components were present in the studied range of 230 to 320K, providing, at first sight, no evidence of discontinuity in the hydration water dynamics. However, a qualitative change in the elastic scattering between 240 and 250K suggested a surface freezing-melting transition, when the motions that were localized at lower temperatures became delocalized at higher temperatures. On the basis of previous molecular dynamics simulations of this system, it was argued that interpretation of quasi-elastic neutron scattering data from such a complex interfacial system requires at least qualitative input from simulations, particularly when comparing results from spectrometers with very different energy resolutions and dynamic ranges.Diffusion Processes in Water on Oxide Surfaces: Quasielastic Neutron Scattering Study of Hydration Water in Rutile Nanopowder. Chu, X., Ehlers, G., Mamontov, E., Podlesnyak, A., Wang, W., Wesolowski, D.J.: Physical Review E, 2011, 84[3], 031505