Seminars Archive

Dynamics of electronic structure probed with an X-ray free-electron laser.

Abstract
Free-electron lasers (FELs) offer the possibility to shoot ultrafast electronic structure movies, providing therefore valuable information for a fundamental understanding of ultrafast dynamics in chemistry, biology and materials science. This can be realized in a pump-probe scheme: a pump pulse drives the system under study out of equilibrium and a delayed FEL pulse probes the electronic structure of the system at different times after the pump.The brilliant femtosecond X-ray pulses delivered by FELs over a wide photon range allow core level spectroscopies to be employed as probing techniques. In this talk, I will present recent pump-probe experiments (ultrafast electronic structure movies) at FELs. In particular, we have studied CO desorption from Ru(0001) by means of time resolved RIXS, where a fs-laser excitation (3.1 eV) induces a transition of adsorbed CO on Ru through vibrationally hot states into a long-lived transient. We have also studied by means of time resolved photoemission the electronic structure changes induced on a picosecond time scale on Ir(111) and GaAs(0001) by optical (1.5eV) and X-ray (40eV) pump respectively.