title: Excited-state structure by time-resolved X-ray diffraction.
abstract: X-ray crystallography has traditionally been limited to the study of the ground-state structure of molecules and solids. Recent technical advances are removing this limitation as demonstrated here by a time-resolved stroboscopic study of the photo-induced 50 micros lifetime excited triplet state of the [Pt(2)(pop)(4)](4-)ion [pop = pyrophosphate, (H(2)P(2)O(5))(2-)], performed at helium temperatures with synchrotron radiation. The shortening of the Pt-Pt bond by 0.28(9)A upon excitation is compatible with the proposed mechanism involving promotion of a Pt-Pt antibonding dsigma* electron to a weakly bonding p orbital. The contraction is accompanied by a 3 degree molecular rotation. The time-resolved diffraction technique described here is applicable to reversible light-driven processes in the crystalline solid state.
authors.affiliation: Department of Chemistry, State University of New York at Buffalo, Buffalo, NY 14260-3000, USA.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Kim
authors.forename: Sebastien
authors.initials: S
authors.lastname: Pillet
authors.forename: Guang
authors.initials: G
authors.lastname: Wu
authors.forename: Wilfred K
authors.initials: WK
authors.lastname: Fullagar
authors.forename: Philip
authors.initials: P
authors.lastname: Coppens