What is it about?
We show how ultra-fast X-ray laser pulses – lasting just 30 femtoseconds – can be used to probe the atomic structure of materials in exceptional detail. Using a carefully designed experimental setup at the European X-ray free electron laser (XFEL) in Germany, we capture total scattering data and use pair distribution function (PDF) analysis to reveal the arrangement of atoms in space. We apply this method across a range of materials including crystals, glasses, liquids, and clusters in solution. For the first time, high-quality structural insights with high real-space resolution have been obtained from single XFEL pulses, opening the door to "molecular movies" of structural changes as they happen in real time!
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Why is it important?
Many important processes in chemistry, materials science, and biology – such as catalysis, energy storage, and light-matter interactions – occur in just trillionths of a second. However, most tools for studying atomic structure are too slow to capture these fleeting changes. Our work demonstrates that XFELs can now be used to generate high-resolution structural snapshots on the same timescale as atomic motion. This is a crucial breakthrough: it allows researchers to track how materials behave under rapid stimuli, providing fundamental insights into function, reactivity, and dynamics that were previously out of reach.
Perspectives
I have taken part in many experiments at synchrotron facilities, but this was one of my first experiences using an XFEL and the step up in complexity was quite something! As the long author list suggests, these experiments rely on the combined efforts of a huge team: from detector and sample environment experts to beamline scientists, operators, and the students and researchers who worked tirelessly through the night and then spent months meticulously analysing the data. Every contribution – big or small – was crucial, which makes seeing the work published in IUCrJ especially rewarding. It marks not just a scientific milestone, but a celebration of our collective dedication. Scientifically, I believe this work shows that ultra-fast PDF techniques are ready to become a core method for probing structural dynamics that were previously beyond reach – and I am excited to see what we will uncover next! On a personal note, it has been a great pleasure working so closely with Dave on this project, someone I have known for several years and whose work I greatly admire.
Adam Sapnik
University of Copenhagen
Read the Original
This page is a summary of: High-quality ultra-fast total scattering and pair distribution function data using an X-ray free-electron laser, IUCrJ, July 2025, International Union of Crystallography,
DOI: 10.1107/s205225252500538x.
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