title: Time-Resolved X-ray Spectroscopy in the Water Window: Elucidating Transient Valence Charge Distributions in an Aqueous Fe(II) Complex.
abstract: Time-resolved nitrogen-1s spectroscopy in the X-ray water window is presented as a novel probe of metal-ligand interactions and transient states in nitrogen-containing organic compounds. New information on iron(II) polypyridyl complexes via nitrogen core-level transitions yields insight into the charge density of the photoinduced high-spin state by comparing experimental results with time-dependent density functional theory. In the transient high-spin state, the 3d electrons of the metal center are more delocalized over the nearest-neighbor nitrogen atoms despite increased bond lengths. Our findings point to a strong coupling of electronic states with charge-transfer character, facilitating the ultrafast intersystem crossing cascade in these systems. The study also highlights the importance of local charge density measures to complement chemical interaction concepts of charge donation and back-bonding with molecular orbital descriptions of states.
authors.affiliation: Department of Chemistry, University of Washington , Seattle, Washington 98195, United States.
authors.forename: Benjamin E
authors.initials: BE
authors.lastname: Van Kuiken
authors.affiliation: Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.|Department of Chemistry and Chemistry Institute of Functional Materials, Pusan National University , Busan 46241, Republic of Korea.
authors.forename: Hana
authors.initials: H
authors.lastname: Cho
authors.affiliation: Department of Chemistry and Chemistry Institute of Functional Materials, Pusan National University , Busan 46241, Republic of Korea.
authors.forename: Kiryong
authors.initials: K
authors.lastname: Hong
authors.affiliation: Department of Chemistry, University of Washington , Seattle, Washington 98195, United States.
authors.forename: Munira
authors.initials: M
authors.lastname: Khalil
authors.affiliation: Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Schoenlein
authors.affiliation: Department of Chemistry and Chemistry Institute of Functional Materials, Pusan National University , Busan 46241, Republic of Korea.
authors.forename: Tae Kyu
authors.initials: TK
authors.lastname: Kim
authors.affiliation: Department of Physics, University of Hamburg, Max Planck Institute for the Structure and Dynamics of Matter, and Center for Free-Electron Laser Science , 22761 Hamburg, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Huse