Emergence of pseudoresonance in high-intensity resonant inelastic x-ray scattering

Sang-Kil Son, Thomas M. Baumann, Jacob Pedersen, Laura Budewig, Kai Li, Hans Ågren, Olle Björneholm, Rebecca Boll, John Bozek, Carl Caleman, Sebastian Cardoch, Lucas M. Cornetta, Alberto De Fanis, Emiliano De Santis, Simon Dold, Gilles Doumy, Ulrich Eichmann, Xiaochun Gong, Johan Gråsjö, Alice E. Green, Iyas Ismail, Ludvig Kjellsson, Eva Lindroth, Tommaso Mazza, Jacobo Montaño, Terry Mullins, Christian Ott, Yevheniy Ovcharenko, Thomas Pfeifer, Maria Novella Piancastelli, Ralph Püttner, Nils Rennhack, Nina Rohringer, Cecilia Sánchez-Hanke, Conny Såthe, Philipp Schmidt, Björn Senfftleben, Marc Simon, Nicuşor Tîmneanu, Moto Togawa, Kiyoshi Ueda, Sergey Usenko, Hans Jakob Wörner, Weiqing Xu, Zhong Yin, Linda Young, Joseph Nordgren, Marcus Agåker, Johan Söderström, Sonia Coriani, Michael Meyer, Robin Santra, and Jan-Erik Rubensson

[BibTeX][pdf]doi:10.1103/drmh-vmgk

We report resonant inelastic x-ray scattering (RIXS) spectra of neon atoms interacting with intense x-ray pulses generated using an x-ray free-electron laser (XFEL). We found that an unexpected peak emerges near the Kα line of Ne, which does not coincide with any physical resonances of neon ions. We performed theoretical calculations based on a quantum-state-resolved rate-equation approach with x-ray-induced processes including possible resonant excitations. Our dynamics simulations demonstrate that a sequence of multiple resonant photoabsorption events are involved and the interplay of those multiple resonances in combination with the relatively large spectral bandwidth of XFEL radiation leads to the emergent resonance-like structure at a position where no resonances exist. Our finding offers critical guidance for future applications of high-intensity RIXS at XFEL facilities.

Tags: Ne, resonance, x-ray, RIXS, MRIXS, x-ray multiphoton ionization, state-resolved, XATOM, European XFEL, experiment, XFEL, CFEL, DESY