Super-Resolution in Ultrafast Scattering

Studying matter and dynamics at the level of electrons and atoms requires imaging structures and motions in the sub-Ångstrom and femtosecond scales, as in this range the fundamental properties of materials and physical mechanisms are established.  State-of-the-art instruments such as X-ray free electron lasers, and ultrafast electrons are emerging tools that transform several fields of science because they access the atomic length and time scales without affecting the sample.  However, direct real-space recovery of general and complex atomic motions in disordered materials is still mostly limited to signal interpretation in reciprocal space using system-dependent simulations, due to the insufficient scattering vector and photon energies available.

We will present recent results on how to extend super-resolution methods that transformed microscopy and bio-imaging, to the challenging case of ultrafast scattering, where traditional imaging optics are not available. We introduce theoretically and demonstrate experimentally an inversion and super-resolution method that allows the recovery of multiple sub-diffraction-limit spaced atomic distances from noisy signals.  We will showcase the application of this methodology for elucidating structural dynamics across a range of progressively complex systems, starting from small organic molecules, advancing through transition metal complexes, and culminating in photocatalysts situated within complex environments. The approach directly brings real-space atomic resolutions to the ultrafast timescale, where often only spectroscopic information is recorded.