Seminars Archive

Driven material dynamics studied with free electron laser

Abstract
Ultrafast pulsed excitation of solids allows to create states of strong electronic excitation and high temperature and pressure. Subsequent to the initial deposition of energy a complex chain of secondary relaxation processes can lead to structural changes on very rapid time-scales, and often along unusual, non-equilibrium pathways. These processes have attracted continuing interest for more than three decades, both from a fundamental physics viewpoint as well as with respect to technological applications such as laser-processing and material synthesis. In this contribution I will present examples from our work where we have used the intense, short-pulse and short-wavelength radiation of free electron lasers to probe the transient response of strongly driven materials at the relevant length (i.e. Å to nm) and time (i.e. fs to ps) scales. This includes studies of fs laser-induced melting (both thermal and non-thermal), phase transition dynamics in phase change materials, short pulse laser ablation, and nanoscale structure formation (i.e. ripples) at laser-irradiated surfaces.