Kunnus, K.; Josefsson, I.; Rajkovic, I.; Schreck, S.; Quevedo, W.; Beye, M.; Grübel, S.; Scholz, M.; Nordlund, D.; Zhang, W.; Hartsock, R.W.; Gaffney, K.J.; Schlotter, W.F.; Turner, J.J.; Kennedy, B.; Hennies, F.; Techert, S.; Wernet, P.; Odelius, M.; Föhlisch, A.: Anti-Stokes resonant x-ray Raman scattering for atom specific and excited state selective dynamics. New Journal of Physics 18 (2016), p. 103011/1-9
Open Accesn Version

Ultrafast electronic and structural dynamics of matter govern rate and selectivity of chemical reactions, as well as phase transitions and efficient switching in functional materials. Since x-rays determine electronic and structural properties with elemental, chemical, orbital and magnetic selectivity, short pulse x-ray sources have become central enablers of ultrafast science. Despite of these strengths, ultrafast x-rays have been poor at picking up excited state moieties from the unexcited ones. With time-resolved anti-Stokes resonant x-ray Raman scattering (AS-RXRS) performed at the LCLS, and ab initio theory we establish background free excited state selectivity in addition to the elemental, chemical, orbital and magnetic selectivity of x-rays. This unparalleled selectivity extracts low concentration excited state species along the pathway of photo induced ligand exchange of Fe(CO)5 in ethanol. Conceptually a full theoretical treatment of all accessible insights to excited state dynamics with AS-RXRS with transform-limited x-ray pulses is given—which will be covered experimentally by upcoming transform-limited x-ray sources.