DIFFUSIVE PROPERTIES OF WATER STUDIED BY INCOHERENT QUASI-ELASTIC NEUTRON-SCATTERING

Using a pulsed-source neutron spectrometer we have measured the quasi- elastic incoherent dynamic structure factor of pure water in the tempe rature range 256-293 K. The high energy resolution and the wide energy transfer window allowed us to separate the translational diffusive mo tions from the rotational ones. The translational dynamics has been an alysed on the basis of a random-jump model that describes quite well t he average behaviour of the quasi-elastic broadenings as a function of momentum transfer.