Speaker
Description
Neutron scattering is a unique technique to characterize structural and dynamic properties of matter. Particularly important is the potential, playing with isotopic labelling, of accessing different correlation functions (collective, self) or ‘isolating’ the signal of a given component or molecular group in a complex system. However, the coexistence of coherent and incoherent contributions to the scattered intensity is, in most of the situations, unavoidable. These contributions can only be separated by applying polarization analysis – which poses technical difficulties. The recent implementation of this capability in spectrometers, in particular in the case of PLET at ISIS with sub-meV resolution, opens the possibility of investigating problems / systems that could not be approached in a rigorous way until now. One of them is the question of the collective dynamics of liquids and glass-forming systems in the mesoscale or intermediate length scales region, i. e., at length scales larger than the intermolecular ones but not yet in the hydrodynamic regime. In this talk, new insights on the problem of how collective and self-dynamics evolve from intermediate to intermolecular length scales will be presented, considering systems with different intermolecular interactions. They have been provided by the application of spectroscopy with polarization analysis as well as using the NSE technique as an alternative and complementary way to address self- and collective dynamics. We will also show the great help of molecular dynamics simulations to interpret the experimental results.
