Hannover 2013 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 19: Interaction with VUV and X-ray light II

A 19.7: Vortrag

Dienstag, 19. März 2013, 15:30–15:45, F 428

Multiphoton inner-shell excitation in rare gas atoms — •Tommaso Mazza¹, Markus Ilchen¹, Thomas J. Kelly², Sadegh Bakhtiarzadeh¹, Amir Jones Rafipoor¹, John Costello², Stefan Dusterer³, Peter Lambropoulos⁴, Stephan Fritzsche⁵, and Michael Meyer¹ — ¹European XFEL GmbH, Hamburg, Germany — ²DCU, Dublin, Ireland — ³Hasylab@DESY, Hamburg, Germany — ⁴University of Crete, Heraklion, Greece — ⁵GSI, Darmstadt, Germany

We present a study of direct and resonant two- and multi-photon ionization processes in the XUV regime in Xe and Ar, performed at the Free electron LASer in Hamburg (FLASH). The strong interaction of short wavelength intense radiation with the strongly bound core electron results in new and mostly unexplored photoexcitation phenomena through the simultaneous absorption of two (or more) photons. These are responsible for the highly charged states observed earlier by ion spectroscopy, and are investigated here in detail by means of photoelectron spectroscopy. In particular, we were able to unambiguously identify the signatures of direct 2-photon as well as sequential multi-photon ionization processes of Ar3p and Xe4d, and of the Auger decay of the (1photon forbidden) 2-photon Ar2p-4p resonance excitation.

Detailed understanding of these non-linear processes, which are driven by the very intense FEL radiation and which have been almost completely unexplored up to now in the XUV wavelength regime to date, is crucial not only for gas phase experiments, but also for FEL-based studies in all other targets from molecules to solids.