Ilchen, M.; Schmidt, P.; Novikovskiy, N.M.; Hartmann, G.; Rupprecht, P.; Coffee, R.N.; Ehresmann, A.; Galler, A.; Hartmann, N.; Helml, W.; Huang, Z.; Inhester, L.; Lutman, A.A.; MacArthur, J.P.; Maxwell, T.; Meyer, M.; Music, V.; Nuhn, H.D.; Osipov, T.; Ray, D.; Wolf, T.J.A.; Bari, S.; Walter, P.; Li, Z.; Moeller, S.; Knie, A.; Demekhin, P.V.: Site-specific interrogation of an ionic chiral fragment during photolysis using an X-ray free-electron laser. Communications Chemistry 4 (2021), p. 119/1-9
10.1038/s42004-021-00555-6
Open Access Version
Abstract:
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 recognition.