Site specific interrogation of an ionic chiral fragment during photolysis using an X ray free electron laser

Ultrashort circularly polarised light pulses from free electron lasers offer a route for exploring chiral molecules and their dynamics, but remain challenging to harness. Here, X ray pump probe experiments enable a site specific photoelectron circular dichroism measurement on a dissociating chiral molecule. Short wavelength free electron lasers with their ultrashort pulses at high intensities have originated new approaches for tracking molecular dynamics from the vista of specific sites. X ray pump X ray probe schemes even allow to address individual atomic constituents with a trigger event that preludes the subsequent molecular dynamics while being able to selectively probe the evolving structure with a time delayed second X ray pulse. Here, we use a linearly polarized X ray photon to trigger the photolysis of a prototypical chiral molecule, namely trifluoromethyloxirane C3H3F3O , at the fluorine K edge at around 700 eV. The created fluorine containing fragments are then probed by a second, circularly polarized X ray pulse of higher photon energy in order to investigate the chemically shifted inner shell electrons of the ionic mother fragment for their stereochemical sensitivity. We experimentally demonstrate and theoretically support how two color X ray pump X ray probe experiments with polarization control enable XFELs as tools for chiral recognitio