title: Highly accurate excited-state structure of [Os(bpy)2dcbpy](2+) determined by X-ray transient absorption spectroscopy.
abstract: Determining the electronic and geometric structures of photoexcited transient species with high accuracy is crucial for understanding their fundamental photochemistry and controlling their photoreactivity. We have applied X-ray transient absorption spectroscopy to measure the XANES and EXAFS spectra of a dilute (submillimolar) solution of the osmium(II) polypyridyl complex [Os(bpy)2dcbpy](PF6)2 (dcbpy = 4,4'-dicarboxy-2,2'-bipyridine) (OsL2L') in methanol at the Os LIII edge. We have obtained spectra of superb quality for both the ground state and the photoinduced (3)MLCT excited state that have allowed us not only to extract detailed information about the Os 5d orbitals but also to resolve very small differences of 0.010 ± 0.008 Å in the average Os-N bond lengths of the ground and excited states. Theoretical calculations using a recently developed DFT-based approach support the measured electronic structures and further identify the nature of the molecular orbitals that contribute to the main absorption bands in the XANES spectra.
authors.affiliation: X-ray Sciences Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.
authors.forename: Xiaoyi
authors.initials: X
authors.lastname: Zhang
authors.forename: Sophie E
authors.initials: SE
authors.lastname: Canton
authors.forename: Grigory
authors.initials: G
authors.lastname: Smolentsev
authors.forename: Carl-Johan
authors.initials: CJ
authors.lastname: Wallentin
authors.forename: Yizhu
authors.initials: Y
authors.lastname: Liu
authors.forename: Qingyu
authors.initials: Q
authors.lastname: Kong
authors.forename: Klaus
authors.initials: K
authors.lastname: Attenkofer
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Stickrath
authors.forename: Michael W
authors.initials: MW
authors.lastname: Mara
authors.forename: Lin X
authors.initials: LX
authors.lastname: Chen
authors.forename: Kenneth
authors.initials: K
authors.lastname: Wärnmark
authors.forename: Villy
authors.initials: V
authors.lastname: Sundström