Intense X Rays Can Free Bound Electrons

T he x-ray free-electron laser (XFEL) is a revolutionary tool for investigating light–matter interactions. The quick-fire pulses of high-energy radiation used in this tool can capture a fast succession of snapshots of a material’s atoms, revealing the fine-scale, three-dimensional details of atomic movements without destroying a sample. Still, the intense irradiation of an XFEL has the potential to alter both the electronic and atomic configurations of a material, which complicates the determination of a solid’s structure. Now Ichiro Inoue of RIKEN in Japan and his colleagues have pinpointed when and how an XFEL’s pulses alter the crystal structures they are designed to reveal [1]. The results could help resolve limitations of the technology and could be used to improve accuracy in future XFEL imaging.