Mainz 2017 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 8: XUV/X-ray spectroscopy II
A 8.2: Hauptvortrag
Montag, 6. März 2017, 17:30–18:00, N 2
Circular Dichroism in Multi-Photon Ionization of Oriented Helium Ions — •Markus Ilchen1, Nicolas Douguet2, Tommaso Mazza1, Klaus Bartschat2, Alexei Grum-Grzhimailo3, Nikolay Kabachnik3, and Michael Meyer1 — 1European XFEL GmbH, Schenefeld, Germany — 2Drake University, Des Moins, USA — 3Lomonosow Moscow State University, Moscow, Russia
The dichroic interaction of circularly polarized X-rays with matter is a multi-disciplinary field of science. With the advent of circularly polarized free-electron laser (FEL) radiation [1,2], the research field of circular dichroism phenomena in non-linear and ultrafast physics has been extended to the soft X-ray regime. Using high intensity, narrow bandwidth XUV pulses from FERMI in Italy, we were able to resonantly orient ionic helium in the 3p (m=+1) magnetic sub-state and to control the population of this state by a helicity dependent AC Stark shift generated by an overlapped near-infrared laser. The measured circular dichroism of electrons emitted via multi-photon ionization of the 3p state is intensity dependent to a surprisingly strong extent, therefore, allowing for an easily controllable and polarization selective transparency of such resonances. Potential applications in the general context of chirality research at FELs will be discussed. [1] E. Allaria et al., Phys. Rev. X, 4, 041040 (2014) [2] A. A. Lutman et al., Nature Photon., 10, 468 (2016)