Collect. Czech. Chem. Commun. 2008, 73, 1475-1494

Photodissociation Pathways of Acetone Upon Excitation Into the 3s Rydberg State: Adiabatic Versus Diabatic Mechanism

Ivana Antola,*, Mirjana Eckert-Maksića, Milan Ončákb, Petr Slavíčekb,* and Hans Lischkac,*

a Division of Organic Chemistry and Biochemistry, Rudjer Bošković Institute, P.O. Box 180, HR-10002 Zagreb, Croatia
b Department of Physical Chemistry, Institute of Chemical Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic
c Institute for Theoretical Chemistry, University of Vienna, Waehringerstrasse 17, A-1090 Vienna, Austria


Photolysis of acetone upon excitation to the 3s Rydberg excited state has been studied by means of high level ab initio methods. The calculations have been performed on multiconfigurational self consistent field (MCSCF) level with a subsequent addition of dynamical correlation both by perturbation theory (CASPT2) and via a configuration interaction expansion up to double excitations (MR-CISD). In addition to the major photoreaction that is well known Norrish type α-cleavage, the formation of hydrogen and acetonyl (1-methyloxy or 2-oxopropyl) radical has been discussed. The major question addressed is whether the dynamical processes occur adiabatically on the S2 surface or diabatically, with non-adiabatic transitions taking place in the course of the reactions.

Keywords: Ab initio calculations; Acetone; Conical intersections; Deactivation mechanisms; Photochemistry; Photolysis; Reaction mechanism; Radicals; Norrish cleavage.

References: 81 live references.