High-quality ultra-fast total scattering and pair distribution function data using an X-ray free-electron laser.

Area of Science:

• Materials Science
• Condensed Matter Physics
• X-ray Scattering

Background:

• High-quality total scattering data are crucial for understanding atomic structures in disordered materials.
• Traditional synchrotron methods struggle to capture ultrafast structural dynamics due to millisecond timescale limitations.
• X-ray free-electron lasers (XFELs) offer femtosecond X-ray pulses, presenting an opportunity for ultrafast scattering studies.

Purpose of the Study:

• To demonstrate the capability of XFELs for ultrafast total scattering measurements.
• To extend the accessible momentum transfer (Q) range for XFEL-based scattering experiments.
• To validate XFELs as a viable tool for researchers utilizing total scattering and pair distribution function (PDF) analysis.

Main Methods:

• Utilized the HED scientific instrument at the European XFEL with high-energy X-ray beams.
• Collected normalized total scattering data (S(Q)) and pair distribution functions (PDFs) across a broad Q range (0.35–16.6 Å⁻¹).
• Employed diverse analytical techniques including Rietveld refinement, PDF refinement, and Debye scattering analysis.

Main Results:

• Achieved high-quality total scattering data from single femtosecond XFEL pulses (∼30 fs).
• Successfully measured data from various sample types: crystalline, nanocrystalline, amorphous solids, liquids, and solutions.
• Significantly expanded the maximum Q range for XFEL-based S(Q) measurements.

Conclusions:

• XFELs are now a practical and powerful source for ultrafast total scattering and PDF studies.
• The demonstrated capabilities enable the investigation of atomic motion on femtosecond timescales.
• This advancement opens new research avenues for the broad scientific community using scattering techniques.