Vankó, György9; Bordage, Amélie9; Glatzel, Pieter10; Gallo, Erik10; Rovezzi, Mauro10; Gawelda, Wojciech4; Galler, Andreas4; Bressler, Christian4; Doumy, Gilles11; March, Anne Marie11; Kanter, Elliot P.11; Young, Linda11; Southworth, Stephen H.11; Canton, Sophie E.12; Uhlig, Jens12; Smolentsev, Grigory12; Sundström, Villy12; Haldrup, Kristoffer1; Brandt van Driel, Tim7; Nielsen, Martin Meedom1; Kjaer, Kasper S.8; Lemke, Henrik T.8
1 Department of Physics, Technical University of Denmark2 Hungarian Academy of Sciences3 European Synchrotron Radiation Facility4 European XFEL5 Argonne National Laboratory6 Lund University7 Risø National Laboratory for Sustainable Energy, Technical University of Denmark8 University of Copenhagen9 Hungarian Academy of Sciences10 European Synchrotron Radiation Facility11 Argonne National Laboratory12 Lund University
We report on extending hard X-ray emission spectroscopy (XES) along with resonant inelastic X-ray scattering (RIXS) to study ultrafast phenomena in a pump-probe scheme at MHz repetition rates. The investigated systems include low-spin (LS) FeII complex compounds, where optical pulses induce a spin-state transition to their (sub)nanosecond-lived high-spin (HS) state. Time-resolved XES clearly reflects the spin-state variations with very high signal-to-noise ratio, in agreement with HS–LS difference spectra measured at thermal spin crossover, and reference HS–LS systems in static experiments, next to multiplet calculations. The 1s2p RIXS, measured at the Fe 1s pre-edge region, shows variations after laser excitation, which are consistent with the formation of the HS state. Our results demonstrate that X-ray spectroscopy experiments with overall rather weak signals, such as RIXS, can now be reliably exploited to study chemical and physical transformations on ultrafast time scales.
Journal of Electron Spectroscopy and Related Phenomena, 2013, Vol 188, p. 166-171