title: UV absorption spectrum and photodissociation channels of the simplest Criegee intermediate (CH2OO).
abstract: The lowest-lying singlet states of the simplest Criegee intermediate (CH2OO) have been characterized along the O-O dissociation coordinate using explicitly correlated MRCI-F12 electronic structure theory and large active spaces. It is found that a high-level treatment of dynamic electron-correlation is essential to accurately describe these states. A significant well on the B-state is identified at the MRCI-F12 level with an equilibrium structure that differs substantially from that of the ground X-state. This well is presumably responsible for the apparent vibrational structure in some experimental UV absorption spectra, analogous to the structured Huggins band of the iso-electronic ozone. The B-state potential in the Franck-Condon region is sufficiently accurate that an absorption spectrum calculated with a one-dimensional model agrees remarkably well with experiment.
authors.affiliation: Department of Chemistry, Missouri University of Science and Technology , Rolla, Missouri 65409, United States.
authors.forename: Richard
authors.initials: R
authors.lastname: Dawes
authors.forename: Bin
authors.initials: B
authors.lastname: Jiang
authors.forename: Hua
authors.initials: H
authors.lastname: Guo
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D010126:Ozone / Q000737:chemistry*; D055668:Photochemical Processes; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000475:Alkenes; D010126:Ozone