title: Iron L-Edge Absorption Spectroscopy of Iron Pentacarbonyl and Ferrocene in the Gas Phase.
abstract: Fe L-edge X-ray absorption spectra of gas-phase iron pentacarbonyl and ferrocene measured in total-ion yield mode are reported. Comparison to previously published spectra of free iron atoms and gaseous iron chloride demonstrates how the interplay of local atomic multiplet effects and orbital interactions in the metal-ligand bonds varies for the different systems. We find changes in the degree of metal-ligand covalency to be reflected in the measured 2p absorption onset. Orbital- or state-specific fragmentation is furthermore investigated in iron pentacarbonyl and ferrocene by analyzing the partial-ion-yield spectra at the Fe L-edge. Strong dependence of the yields of different fragments is observed in ferrocene in contrast to iron pentacarbonyl. This difference is attributed to the different degrees to which the 2p core hole is screened in the two systems and to which charge is rearranged in the Auger final states. We provide experimental benchmark spectra for new ab initio approaches for calculating metal L-edge absorption spectra of metal complexes.
authors.affiliation: Helmholtz-Zentrum Berlin , Hahn-Meitner-Platz 1, 14109 Berlin, Germany.
authors.forename: Kai
authors.identifier: http://orcid.org/0000-0002-4406-4212
authors.initials: K
authors.lastname: Godehusen
authors.affiliation: European Spallation Source , Ole Maaløes Vej 3, 2200 Copenhagen, Denmark.
authors.forename: Tobias
authors.initials: T
authors.lastname: Richter
authors.affiliation: Technische Universität Berlin , Hardenbergstraße 36, 10623 Berlin, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Zimmermann
authors.affiliation: Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Albert-Einstein-Straße 15, 12489 Berlin, Germany.
authors.forename: Philippe
authors.initials: P
authors.lastname: Wernet