Speaker: Kirsten Schnorr, Paul Scherrer Institut (PSI)
Program Description:
The soft X-ray branch Athos at SwissFEL has been designed to produce intense short soft X-ray pulses (250 eV to 1800 eV) with multiple colors. The Maloja endstation has been tailored to make ideal use of these special beam modes by providing a flexible platform to combine multiple experimental techniques and to enable new experiment geometries. The unique combination of Athos and Maloja allows to investigate a large range of phenomena in the field of atomic, molecular, non-linear and chemical sciences ranging from ultrafast dynamics to non-linear X-ray sciences. During this talk, I am going to present first results from the endstation commissioning and the pilot experiment phase.
Multi-color X-ray pulses with adjustable delay allow to follow ultrafast charge and energy transfer in time and space due to the state selectivity of X-ray photoabsorption. With two freely tunable X-ray pump-probe energies from the Athos line, we can excite at one atomic site and monitor subsequent relaxation processes throughout a system at another site. In this talk, I will show results from our first two-color experiment on small gas-phase molecules. We employed transient absorption spectroscopy to track the core-excitation induced dynamics in nitrous oxide by exciting the molecules with a pump pulse tuned to the nitrogen K-edge and probing with a pulse tuned to the oxygen K-edge. Pushing the pulse duration into the few to sub-fs regime will give access to study X-ray induced dynamics on sub-Auger lifetimes. This is crucial to understand processes like charge migration or the initial steps of radiation damage, and to implement nonlinear X-ray spectroscopy techniques.
