caa a22 4500 530098784 20181217030326.0 cr unu---uuuuu 181026e20160913xx s 000 0 eng 10.3929/ethz-b-000120885 doi 10.1038/srep33292 doi (ETHRESEARCH)oai:www.research-collection.ethz.ch:20.500.11850/120885 Establishing nonlinearity thresholds with ultraintense X-ray pulses [Elektronische Daten] [Jakub Szlachetko, Joanna Hoszowska, Jean-Claude Dousse, Maarten Nachtegaal, Wojciech Blachucki, Yves Kayser, Jacinto Sà, Marc Messerschmidt, Sébastien Boutet, Garth J. Williams, Christian David, Grigory Smolentsev, Jeroen A. van Bokhoven, Bruce D. Patterson, Thomas J. Penfold, Gregor Knopp, Marek Pajek, Rafael Abela, Christopher J. Milne] Sci Rep Open access ethresearch X-ray techniques have evolved over decades to become highly refined tools for a broad range of investigations. Importantly, these approaches rely on X-ray measurements that depend linearly on the number of incident X-ray photons. The advent of X-ray free electron lasers (XFELs) is opening the ability to reach extremely high photon numbers within ultrashort X-ray pulse durations and is leading to a paradigm shift in our ability to explore nonlinear X-ray signals. However, the enormous increase in X-ray peak power is a double-edged sword with new and exciting methods being developed but at the same time well-established techniques proving unreliable. Consequently, accurate knowledge about the threshold for nonlinear X-ray signals is essential. Herein we report an X-ray spectroscopic study that reveals important details on the thresholds for nonlinear X-ray interactions. By varying both the incident X-ray intensity and photon energy, we establish the regimes at which the simplest nonlinear process, two-photon X-ray absorption (TPA), can be observed. From these measurements we can extract the probability of this process as a function of photon energy and confirm both the nature and sub-femtosecond lifetime of the virtual intermediate electronic state. Creative Commons Attribution 4.0 International http://creativecommons.org/licenses/by/4.0 ethresearch Condensed-matter physics ethresearch Szlachetko Jakub joint author Hoszowska Joanna joint author Dousse Jean-Claude joint author Nachtegaal Maarten joint author Blachucki Wojciech joint author Kayser Yves joint author Sà Jacinto joint author Messerschmidt Marc joint author Boutet Sébastien joint author Williams Garth J. joint author David Christian joint author Smolentsev Grigory joint author van Bokhoven Jeroen A. joint author Patterson Bruce D. joint author Penfold Thomas J. joint author Knopp Gregor joint author Pajek Marek joint author Abela Rafael joint author Milne Christopher J. joint author Scientific Reports London : Nature Publishing Group 6, p. 33292 2045-2322 http://hdl.handle.net/20.500.11850/120885 text/html WWW-Backlink auf das Repository (Open access) 1 Journal Article ethresearch ETHRESEARCH 856 40 http://hdl.handle.net/20.500.11850/120885 text/html WWW-Backlink auf das Repository (Open access) ETHRESEARCH 700 1- Szlachetko Jakub joint author ETHRESEARCH 700 1- Hoszowska Joanna joint author ETHRESEARCH 700 1- Dousse Jean-Claude joint author ETHRESEARCH 700 1- Nachtegaal Maarten joint author ETHRESEARCH 700 1- Blachucki Wojciech joint author ETHRESEARCH 700 1- Kayser Yves joint author ETHRESEARCH 700 1- Sà Jacinto joint author ETHRESEARCH 700 1- Messerschmidt Marc joint author ETHRESEARCH 700 1- Boutet Sébastien joint author ETHRESEARCH 700 1- Williams Garth J. joint author ETHRESEARCH 700 1- David Christian joint author ETHRESEARCH 700 1- Smolentsev Grigory joint author ETHRESEARCH 700 1- van Bokhoven Jeroen A. joint author ETHRESEARCH 700 1- Patterson Bruce D. joint author ETHRESEARCH 700 1- Penfold Thomas J. joint author ETHRESEARCH 700 1- Knopp Gregor joint author ETHRESEARCH 700 1- Pajek Marek joint author ETHRESEARCH 700 1- Abela Rafael joint author ETHRESEARCH 700 1- Milne Christopher J. joint author ETHRESEARCH 773 0- Scientific Reports London : Nature Publishing Group 6, p. 33292 2045-2322 BK010053 XK010053 XK010000 ETHRESEARCH ETHRESEARCH ETHRESEARCH Journal Article Open access