Inelastic X-ray scattering and the high-frequency dynamics of disordered systems

Inelastic X-ray scattering (IXS) is a novel spectroscopic technique that recently came up in addition to inelastic neutron scattering (INS), allowing one a determination of the microscopic dynamics in the Thz frequency region and over lengthscales comparable to the mean interparticle separations. The experimental basis of this method will be illustrated, along with a recent selection of examples on its application to the study of the high-frequency collective modes in liquids and glasses, emphasizing the relative merits and drawbacks with respect of INS. In particular, it will be shown how on the snapshot timescale accessed by IXS both the dynamics of the glassy and of the liquid state exhibi