Hannover 2010 – scientific programme
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A: Fachverband Atomphysik
A 11: Interaction with VUV and X-Ray Light I
A 11.1: Talk
Wednesday, March 10, 2010, 10:30–10:45, B 302
Two-Photon double ionization of He at FLASH — •Moritz Kurka1, Artem Rudenko2, Lutz Foucar2, Kai-Uwe Kühnel1, Yuhai Jiang1, Oliver Herrwerth3, Matthias Lezius3, Matthias Kling3, Jeroen van Tilborg4, Ali Belkacem4, Michael Schulz5, Stefan Düsterer6, Rolf Treusch6, Claus Dieter Schröter1, Robert Moshammer1, and Joachim Ullrich1,2 — 1Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany — 2Max-Planck Advanced Study Group at CFEL, 22607 Hamburg, Germany — 3Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany — 4Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA — 5Physics Department and LAMOR, University of Missouri-Rolla, Rolla, MO 65409, USA — 6DESY, 22607 Hamburg, Germany
Free electron lasers such as the FLASH which started operation in 2005 deliver light at unprecedented intensities in the VUV region. Hence they enable for the first time to probe fundamental non-linear few-photon processes in this spectral region. One prominent example is the so called direct channel in two-photon double ionization of Helium, where the absorption of two photons leads to a direct transition from the ground state of the neutral atom to the doubly ionized continuum. This channel serves as an ideal testing ground for effects due to electron-electron correlation in non-linear ionization reactions and therefore sparked substantial theoretical interest in the last few years [1]. Here we report on the first differential measurements on this reaction at two different photon energies.
[1] J. Feist et al., PRA 77, 043420 (2008).