title: Electronic ground states of Fe2(+) and Co2(+) as determined by x-ray absorption and x-ray magnetic circular dichroism spectroscopy.
abstract: The (6)Π electronic ground state of the Co2 (+) diatomic molecular cation has been assigned experimentally by x-ray absorption and x-ray magnetic circular dichroism spectroscopy in a cryogenic ion trap. Three candidates, (6)Φ, (8)Φ, and (8)Γ, for the electronic ground state of Fe2 (+) have been identified. These states carry sizable orbital angular momenta that disagree with theoretical predictions from multireference configuration interaction and density functional theory. Our results show that the ground states of neutral and cationic diatomic molecules of 3d transition elements cannot generally be assumed to be connected by a one-electron process.
authors.affiliation: Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Zamudio-Bayer
authors.affiliation: Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Hirsch
authors.affiliation: Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Langenberg
authors.affiliation: Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Ławicki
authors.affiliation: Cluster Research Laboratory, Toyota Technological Institute, 717-86 Futamata, Ichikawa, Chiba 272-0001, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Terasaki
authors.affiliation: Physikalisches Institut, Universität Freiburg, Stefan-Meier-Straße 21, 79104 Freiburg, Germany.
authors.forename: B
authors.initials: B
authors.lastname: V Issendorff
authors.affiliation: Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany.
authors.forename: J T
authors.initials: JT
authors.lastname: Lau