High-Quality Ultra-Fast Total Scattering and Pair Distribution Function Data using an X-ray Free Electron Laser
Abstract
High-quality total scattering data, a key tool for understanding atomic-scale structure in disordered materials, require stable instrumentation and access to high momentum transfers. This is now routine at dedicated synchrotron instrumentation using high-energy X-ray beams, but it is very challenging to measure a total scattering dataset in less than a few microseconds. This limits their effectiveness for capturing structural changes that occur at the much faster timescales of atomic motion. Current X-ray free-electron lasers (XFELs) provide femtosecond-pulsed X-ray beams with maximum energies of approximately 24 keV, giving the potential to measure total scattering and the attendant pair distribution functions (PDFs) on femtosecond timescales. Here, we show that this potential has been realised using the HED scientific instrument at the European XFEL and present normalised total scattering data for 0.35 \r{A}-1 < Q < 16.6 \r{A}-1 and their PDFs from a broad spectrum of materials, including crystalline, nanocrystalline and amorphous solids, liquids, and clusters in solution. We analyse the data using a variety of methods, including Rietveld refinement, small-box PDF refinement, joint reciprocal-real space refinement, cluster refinement, and Debye scattering analysis. The resolution function of the setup is also characterised. We conclusively show that high-quality data can be obtained from a single approximately 30 fs XFEL pulse. Our efforts not only significantly increase the existing maximum reported Q-range for an S(Q) measured at an XFEL but also mean that XFELs are now a viable X-ray source for the broad community of people using reciprocal space total scattering and PDF methods in their research.
Cite
@article{arxiv.2504.21462,
title = {High-Quality Ultra-Fast Total Scattering and Pair Distribution Function Data using an X-ray Free Electron Laser},
author = {Adam F. Sapnik and Philip A. Chater and Dean S. Keeble and John S. O. Evans and Federica Bertolotti and Antonietta Guagliardi and Lise J. Støckler and Elodie A. Harbourne and Anders B. Borup and Rebecca S. Silberg and Adrien Descamps and Clemens Prescher and Benjamin D. Klee and Axel Phelipeau and Imran Ullah and Kárel G. Medina and Tobias A. Bird and Viktoria Kaznelson and William Lynn and Andrew L. Goodwin and Bo B. Iversen and Celine Crepisson and Emil S. Bozin and Kirsten M. Ø. Jensen and Emma E. McBride and Reinhard B. Neder and Ian Robinson and Justin Wark and Michal Andrzejewski and Ulrike Boesenberg and Erik Brambrink and Carolina Camarda and Valerio Cerantola and Sebastian Goede and Hauke Höppner and Oliver S. Humphries and Zuzana Konopkova and Naresh Kujala and Thomas Michelat and Motoaki Nakatsutsumi and Alexander Pelka and Thomas R. Preston and Lisa Randolph and Michael Roeper and Andreas Schmidt and Cornelius Strohm and Minxue Tang and Peter Talkovski and Ulf Zastrau and Karen Appel and David A. Keen},
journal= {arXiv preprint arXiv:2504.21462},
year = {2025}
}