title: Revisiting the Nonadiabatic Process in 1,2-Dioxetane.
abstract: Determining the ground and excited-state decomposition mechanisms of 1,2-dioxetane is essential to understand the chemiluminescence and bioluminescence phenomena. Several experimental and theoretical studies has been performed in the past without reaching a converged description. The reason is in part associated with the complex nonadiabatic process taking place along the reaction. The present study is an extension of a previous work (De Vico, L.; Liu, Y.-J.; Krogh, J. W.; Lindh, R. J. Phys. Chem. A 2007, 111, 8013-8019) in which a two-step mechanism was established for the chemiluminescence involving asynchronous O-O' and C-C' bond dissociations. New high-level multistate multi configurational reference second-order perturbation theory calculations and ab initio molecular dynamics simulations at constant temperature are performed in the present study, which provide further details on the mechanisms and allow to rationalize further experimental observations. In particular, the new results explain the high ratio of triplet to singlet dissociation products.
authors.affiliation: Department of Chemistry, Ångström, Uppsala University , P.O. Box 518, SE-751 20 Uppsala, Sweden.
authors.forename: Pooria
authors.initials: P
authors.lastname: Farahani
authors.affiliation: Instituto de Ciencia Molecular, Universitat de València , P.O. Box 22085, ES-46071 València, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Roca-Sanjuán
authors.affiliation: Departamento de Quimica Fisica, Universidad de Alcalá , E-28871, Alcalá de Henares, Madrid, Spain.
authors.forename: Felipe
authors.initials: F
authors.lastname: Zapata
authors.affiliation: Department of Chemistry, Ångström, Uppsala University , P.O. Box 518, SE-751 20 Uppsala, Sweden.
authors.forename: Roland
authors.initials: R
authors.lastname: Lindh