Speaker: Alessandro Cunsolo, Brookhaven National Laboratory
Abstract: Since the end of the past millennium, high-resolution Inelastic X-Ray Scattering (IXS) has substantially improved our knowledge of the collective molecular dynamics of disordered systems. This technique enabled us to explore a host of phenomena occurring over distance and time windows respectively approaching nearest neighbor atomic separations and ‘in cage’ oscillation periods. It elucidated fundamental aspects of the high-frequency transport properties of fluids, such as the persistence of extended hydrodynamic excitations beyond the continuous limit, the microscopic mechanism driving relaxation phenomena, and the onset of quantum effects. In more recent years, an increasing number of IXS investigations have been focusing on more complex mesoscale structures promising new functionalities; the outcome of these studies could inspire new routes to manipulate the high-frequency acoustic propagation in materials. Finally, technical improvements of IXS and other synchrotron-based methods could soon enable a whole new class of investigations of transient phenomena in metastable states or undergoing a phase transition.