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Engel RY, Alexander O, Atak K, Bovensiepen U, Buck J, Carley R, Cascella M, Chardonnet V, Chiuzbaian GS, David C, Döring F, Eschenlohr A, Gerasimova N, de Groot F, Guyader LL, Humphries OS, Izquierdo M, Jal E, Kubec A, Laarmann T, Lambert CH, Lüning J, Marangos JP, Mercadier L, Mercurio G, Miedema PS, Ollefs K, Pfau B, Rösner B, Rossnagel K, Rothenbach N, Scherz A, Schlappa J, Scholz M, Schunck JO, Setoodehnia K, Stamm C, Techert S, Vinko SM, Wende H, Yaroslavtsev AA, Yin Z, Beye M. Electron population dynamics in resonant non-linear x-ray absorption in nickel at a free-electron laser. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2023; 10:054501. [PMID: 37841290 PMCID: PMC10576398 DOI: 10.1063/4.0000206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 09/20/2023] [Indexed: 10/17/2023]
Abstract
Free-electron lasers provide bright, ultrashort, and monochromatic x-ray pulses, enabling novel spectroscopic measurements not only with femtosecond temporal resolution: The high fluence of their x-ray pulses can also easily enter the regime of the non-linear x-ray-matter interaction. Entering this regime necessitates a rigorous analysis and reliable prediction of the relevant non-linear processes for future experiment designs. Here, we show non-linear changes in the L 3 -edge absorption of metallic nickel thin films, measured with fluences up to 60 J/cm2. We present a simple but predictive rate model that quantitatively describes spectral changes based on the evolution of electronic populations within the pulse duration. Despite its simplicity, the model reaches good agreement with experimental results over more than three orders of magnitude in fluence, while providing a straightforward understanding of the interplay of physical processes driving the non-linear changes. Our findings provide important insights for the design and evaluation of future high-fluence free-electron laser experiments and contribute to the understanding of non-linear electron dynamics in x-ray absorption processes in solids at the femtosecond timescale.
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Affiliation(s)
| | - Oliver Alexander
- Department of Physics, Imperial College London, London, United Kingdom
| | - Kaan Atak
- Deutsches Elektronen-Synchrotron DESY, Germany
| | | | | | | | | | - Valentin Chardonnet
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement LCPMR, Paris, France
| | - Gheorghe Sorin Chiuzbaian
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement LCPMR, Paris, France
| | | | | | - Andrea Eschenlohr
- Faculty of Physics and Center for Nanointegration Duisburg-Essen CENIDE, University of Duisburg-Essen, Duisburg, Germany
| | | | - Frank de Groot
- Debye Institute for Nanomaterials Science, Inorganic Chemistry and Catalysis, Utrecht University, Utrecht, The Netherlands
| | | | | | | | - Emmanuelle Jal
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement LCPMR, Paris, France
| | - Adam Kubec
- Paul Scherrer Institut, Villigen, Switzerland
| | | | | | - Jan Lüning
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin, Germany
| | | | | | | | | | - Katharina Ollefs
- Faculty of Physics and Center for Nanointegration Duisburg-Essen CENIDE, University of Duisburg-Essen, Duisburg, Germany
| | - Bastian Pfau
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Berlin, Germany
| | | | | | - Nico Rothenbach
- Faculty of Physics and Center for Nanointegration Duisburg-Essen CENIDE, University of Duisburg-Essen, Duisburg, Germany
| | | | | | | | | | | | | | | | | | - Heiko Wende
- Faculty of Physics and Center for Nanointegration Duisburg-Essen CENIDE, University of Duisburg-Essen, Duisburg, Germany
| | | | | | - Martin Beye
- Author to whom correspondence should be addressed:
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