Core-level nonlinear spectroscopy triggered by stochastic X-ray pulses

• Published in: Nature communications Vol. 10; no. 1; pp. 4761 - 10
• Main Authors: Kayser, Yves, Milne, Chris, Juranić, Pavle, Sala, Leonardo, Czapla-Masztafiak, Joanna, Follath, Rolf, Kavčič, Matjaž, Knopp, Gregor, Rehanek, Jens, Błachucki, Wojciech, Delcey, Mickaël G., Lundberg, Marcus, Tyrała, Krzysztof, Zhu, Diling, Alonso-Mori, Roberto, Abela, Rafael, Sá, Jacinto, Szlachetko, Jakub
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 18.10.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 639/624/400/1106; 639/766/36/1121; Atomic and molecular interactions with photons; ATOMIC AND MOLECULAR PHYSICS; Electron states; Electronic structure; Electrons; Formalism; Humanities and Social Sciences; Irradiation; Mapping; multidisciplinary; Nervous system; Opacity; Organic chemistry; Science; Science (multidisciplinary); Spectroscopy; Stochastic processes; X-rays
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-12717-1

Stochastic processes are highly relevant in research fields as different as neuroscience, economy, ecology, chemistry, and fundamental physics. However, due to their intrinsic unpredictability, stochastic mechanisms are very challenging for any kind of investigations and practical applications. Here we report the deliberate use of stochastic X-ray pulses in two-dimensional spectroscopy to the simultaneous mapping of unoccupied and occupied electronic states of atoms in a regime where the opacity and transparency properties of matter are subject to the incident intensity and photon energy. A readily transferable matrix formalism is presented to extract the electronic states from a dataset measured with the monitored input from a stochastic excitation source. The presented formalism enables investigations of the response of the electronic structure to irradiation with intense X-ray pulses while the time structure of the incident pulses is preserved. Free electron X-ray laser pulses, generated by self-amplified spontaneous emission, are stochastic in nature. Here the authors present a reconstruction method for 2D spectroscopy while preserving the intrinsic properties of the incident pulses and apply it to a study towards X-ray intensity induced effects.