Ultra-efficient ionization of heavy atoms by intense X-ray free-electron laser pulses
Authors: Benedikt Rudek, Sang-Kil Son, Lutz Foucar, Sascha W. Epp, Benjamin Erk, Robert Hartmann, Marcus Adolph, Robert Andritschke, Andrew Aquila, Nora Berrah, Christoph Bostedt, John Bozek, Nicola Coppola, Frank Filsinger, Hubert Gorke, Tais Gorkhover, Heinz Graafsma, Lars Gumprecht, Andreas Hartmann, Günter Hauser, Sven Herrmann, Helmut Hirsemann, Peter Holl, André Hömke, Loic Journel, Christian Kaiser, Nils Kimmel, Faton Krasniqi, Kai-Uwe Kühnel, Michael Matysek, Marc Messerschmidt, Danilo Miesner, Thomas Möller, Robert Moshammer, Kiyonobu Nagaya, Björn Nilsson, Guillaume Potdevin, Daniel Pietschner, Christian Reich, Daniela Rupp, Gerhard Schaller, Ilme Schlichting, Carlo Schmidt, Florian Schopper, Sebastian Schorb, Claus-Dieter Schröter, Joachim Schulz, Marc Simon, Heike Soltau, Lothar Strüder, Kiyoshi Ueda, Georg Weidenspointner, Robin Santra, Joachim Ullrich, Artem Rudenko, Daniel Rolles
CellNetworks People: Schlichting Ilme
Journal: Nature Photonics.

X-ray free-electron lasers provide unique opportunities for exploring ultrafast dynamics and for imaging the structures of complex systems. Understanding the response of individual atoms to intense X-rays is essential for most free-electron laser applications. First experiments have shown that, for light atoms, the dominant interaction mechanism is ionization by sequential electron ejection, where the highest charge state produced is defined by the last ionic state that can be ionized with one photon. Here, we report an unprecedentedly high degree of ionization of xenon atoms by 1.5 keV free-electron laser pulses to charge states with ionization energies far exceeding the photon energy. Comparing ion charge-state distributions and fluorescence spectra with state-of-the-art calculations, we find that these surprisingly high charge states are created via excitation of transient resonances in highly charged ions, and predict resonance enhanced absorption to be a general phenomenon in the interaction of intense X-rays with systems containing high-Z constituents.