title: Ca K-edge XAS as a probe of calcium centers in complex systems.
abstract: Herein, Ca K-edge X-ray absorption spectroscopy (XAS) is developed as a means to characterize the local environment of calcium centers. The spectra for six, seven, and eight coordinate inorganic and molecular calcium complexes were analyzed and determined to be primarily influenced by the coordination environment and site symmetry at the calcium center. The experimental results are closely correlated to time-dependent density functional theory (TD-DFT) calculations of the XAS spectra. The applicability of this methodology to complex systems was investigated using structural mimics of the oxygen-evolving complex (OEC) of PSII. It was found that Ca K-edge XAS is a sensitive probe for structural changes occurring in the cubane heterometallic cluster due to Mn oxidation. Future applications to the OEC are discussed.
authors.affiliation: Max Planck Institute for Chemical Energy Conversion , Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.
authors.forename: Vlad
authors.initials: V
authors.lastname: Martin-Diaconescu
authors.forename: Marcello
authors.initials: M
authors.lastname: Gennari
authors.forename: Bertrand
authors.initials: B
authors.lastname: Gerey
authors.forename: Emily
authors.initials: E
authors.lastname: Tsui
authors.forename: Jacob
authors.initials: J
authors.lastname: Kanady
authors.forename: Rosalie
authors.initials: R
authors.lastname: Tran
authors.forename: Jacques
authors.initials: J
authors.lastname: Pécaut
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Maganas
authors.forename: Vera
authors.initials: V
authors.lastname: Krewald
authors.forename: Eric
authors.initials: E
authors.lastname: Gouré
authors.forename: Carole
authors.initials: C
authors.lastname: Duboc
authors.forename: Junko
authors.initials: J
authors.lastname: Yano
authors.forename: Theodor
authors.initials: T
authors.lastname: Agapie
authors.forename: Marie-Noelle
authors.initials: MN
authors.lastname: Collomb
authors.forename: Serena
authors.initials: S
authors.lastname: DeBeer
mesh_terms: D002118:Calcium / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011789:Quantum Theory; D056928:X-Ray Absorption Spectroscopy
chemical_list: D009942:Organometallic Compounds; D008345:Manganese; D002118:Calcium