title: L-edge XANES analysis of photoexcited metal complexes in solution.
abstract: Ultrafast X-ray absorption spectroscopy is a powerful tool to observe electronic and geometric structures of short-lived reaction intermediates. The ab initio FEFF9 code is applied to simulate the Pt L(3)-edge XANES spectrum of the photocatalytic diplatinum molecule [Pt(2)(P(2)O(5)H(2))(4)](4-) and the photo-induced changes that occur therein. The spectra are interpreted within a XAFS-like scattering theoretical framework (bound-continuum transitions) or in terms of a final-state local l-projected density of states (LDOS) (bound-bound transitions). By using a novel Bayesian fitting procedure, we show that the ground-state structures obtained independently from the XANES and EXAFS regions of the spectrum are in good agreement with each other. The semi-quantitative result obtained for the Pt-Pt contraction in the excited state is in line with recently published values. The improved theoretical treatment of inelastic losses has shown to result in more accurate peak positions in the above-continuum region of the spectrum which is an important prerequisite for obtaining quantitative structural information from (time-resolved) XANES spectra.
authors.affiliation: Paul Scherrer Institute, Swiss Light Source, 5232 Villigen, Switzerland. renske.vanderveen@psi.ch
authors.forename: Renske M
authors.initials: RM
authors.lastname: van der Veen
authors.forename: Joshua J
authors.initials: JJ
authors.lastname: Kas
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Milne
authors.forename: Van-Thai
authors.initials: VT
authors.lastname: Pham
authors.forename: Amal
authors.initials: A
authors.lastname: El Nahhas
authors.forename: Frederico A
authors.initials: FA
authors.lastname: Lima
authors.forename: Dimali A
authors.initials: DA
authors.lastname: Vithanage
authors.forename: John J
authors.initials: JJ
authors.lastname: Rehr
authors.forename: Rafael
authors.initials: R
authors.lastname: Abela
authors.forename: Majed
authors.initials: M
authors.lastname: Chergui
mesh_terms: D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry; D012996:Solutions / Q000737:chemistry*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D056831:Coordination Complexes; D012996:Solutions; D010984:Platinum