Resonant structures unveiled by the non-linear interaction with X-rays

Speaker: Tommaso Mazza, European XFEL 

Program Description:
The response of atoms to intense X-ray pulses has been the first target of FEL investigations. Yet, even for the simplest systems the response dynamics is still to be understood under several aspects. Besides the obvious competition between sequential ionization and ultrafast decay on the femtosecond time scale, the specific nature of transient electronic states created by photo-absorption critically influences the subsequently evolving dynamics in matter. In this presentation I show how the role of resonances in the interaction of transient ions with X-rays can be indirectly investigated by ion spectrometry, and how a resonance in a transient core-excited ion can be fully mapped by Auger electron spectroscopy. These results benchmark the performances of the SQS Instrument at the EuXFEL and demonstrate the novel possibilities for investigations of ultrafast decaying transient states in the X-ray domain.