Multi-Modal Measurements of X-Ray Induced Surface Reactions in Nano-Scale Systems at XFELs

In recent years, nano-scale materials have emerged as effective catalysts for light-to-chemical energy conversion, with their nano-dimensionality notably enhancing catalytic potential, reaction rates, and yield. These materials are pivotal in clean energy science, where photoexcitation controls surface catalytic reactions through rapid electron excitation and charge carrier generation, initiating reactions on the nanosurface. Understanding the interaction between charge, energy migration, and chemical reactions is vital for advancing light harvesting systems. Here we present a multi-modal method for investigating the chemical and charge dynamics induced through the X-ray ionization of nanoparticles. This approach enables the simultaneous capture of single-shot 3D momentum-resolved ion emission spectra, X-ray photoelectron spectroscopy, and far-field coherent diffraction imaging (CDI) patterns from individual nanoparticles. Results from the experiment conducted using the SQS instrument at EuXFEL demonstrate the feasibility of capturing single-shot diffractive images that can be used to reconstruct the morphology of nanoparticles, while also offering insights into surface chemical reactions induced by X-ray irradiation. The study sheds light on the active participation of generated photoelectrons in catalytic processes, either through direct interaction with surface adsorbates or by generating secondary electrons and radicals that drive the reactions.