Hannover 2020 – scientific programme

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A: Fachverband Atomphysik

A 23: Interaction with VUV and X-ray light I

A 23.5: Talk

Thursday, March 12, 2020, 12:15–12:30, f107

XUV Transient Absorption Spectroscopy on Neon at FLASH — •Thomas Ding¹, Marc Rebholz¹, Lennart Aufleger¹, Maximilian Hartmann¹, Kristina Meyer¹, Alexander Magunia¹, David Wachs¹, Veit Stooß¹, Paul Birk¹, Gergana Borisova¹, Patrick Rupprecht¹, Yonghao Mi¹, Andrew Attar², Thomas Gaumnitz³, Zhi Heng Loh⁴, Sebastian Roling⁵, Marco Butz⁵, Helmut Zacharias⁵, Stefan Düsterer⁶, Rolf Treusch⁶, Stefano Cavaletto¹, Christian Ott¹, and Thomas Pfeifer¹ — ¹Max Planck Institut für Kernphysik, Heidelberg, Germany — ²University of California Berkeley, Berkeley, USA — ³Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland — ⁴Nanyang Technological University Singapore, Singapore — ⁵Westfälische Wilhelms-Universität Münster, Münster, Germany — ⁶Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany

We present transient absorption spectroscopy employing extreme ultraviolet (XUV) pump and probe pulses delivered by the free-electron laser FLASH. We target the neon atom and trace its nonlinear XUV (photon energy 50 eV) interaction with joint high spectral and temporal resolution. This allows us to trace the time-dependent sequential two-photon ionization of neon, transient (2.4-fs time scale) coherence effects near resonances in the produced doubly-charged neon ions (Ne²⁺), and the XUV-induced Stark shift of those ionic resonances. Furthermore, we show how this technique can be used to measure the frequency chirp of XUV-FEL pulses.