title: Impact of vibrational excitation on the kinetics of a nascent ketene.
abstract: The formation and decay of a ketene intermediate photochemically formed from o-nitrobenzaldehyde has been studied by femtosecond UV/Vis and IR spectroscopy. The ketene is formed predominantly within a few 100 fs and to a minor extent within approximately 200 ps via the recombination of a triplet phased bi-radical. In tetrahydrofuran solution the ketene intermediate is seen to form a secondary intermediate with biphasic kinetics. The first phase of this decay occurs within a few picoseconds. It can be attributed to the reaction of vibrationally excited ketenes. The second phase characterized by a time constant of 2 ns is due to the reaction of thermalized molecules. In 2-butanol solution the lifetime of the thermalized ketene is only approximately 60 ps and the rapid and the slow phases of the decay start to merge.
authors.affiliation: Lehrstuhl für BioMolekulare Optik, Fakultät für Physik, LMU München, Oettingenstr. 67, D-80538 München, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Schmierer
authors.forename: Wolfgang J
authors.initials: WJ
authors.lastname: Schreier
authors.forename: Florian O
authors.initials: FO
authors.lastname: Koller
authors.forename: Tobias E
authors.initials: TE
authors.lastname: Schrader
authors.forename: Peter
authors.initials: P
authors.lastname: Gilch
mesh_terms: D001547:Benzaldehydes / Q000737:chemistry*; D005030:Ethylenes / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D007700:Kinetics; D010777:Photochemistry; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
chemical_list: D001547:Benzaldehydes; D005030:Ethylenes; D007659:Ketones; C043850:2-nitrobenzaldehyde; C008223:ketene