Surface plasmon and off electron dynamics in metal nanocrystals and films

The study of electron dynamics in metals in bulk or confined space has been of central importance not only regarding the understanding of their conductivity properties and the applications they engender but also because they constitute a key example for irreversible dynamics in a system that in many respects can be considered as ideal. Recently with the progress in femtosecond laser techniques one can address their dynamics in time scales close to the very early off equilibrium stages and single out the processes that lead to their thermalization. Furthermore with the growing interest for the electron behavior in nanometer size structures the interplay between temporal and special aspects in the thermalization process has moved into the forefront of these studies coupled with the study of the optical nonlinearities of the metallic nanostructures, in particular the metal nanocrystals in glasses. Here we summarize the most recent studies of the photoinduced nonlinearities in noble metal nanostructures in glasses which establish the key role played by the surface plasmon resonance (SPR) through the dielectric confinement and that of the hot electron mechanism. We exploit this sensitivity to these features to address the evolution of the off electron dynamics as well as that of the surface plasmon, a collective dipolar oscillation of the electrons in the nanocrystal which incorporates their interaction with the interface.