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"The complex photo-rearrangement of a heterocyclic N-oxide: kinetics from picoseconds to minutes" Thorben Cordes, Nadja Regner, Björn Heinz, Elina Borysova, Gerald Ryseck, Peter GilchJ. Photochem. Photobiol. A: Chemistry, 206, pp.10-17 (2009) Abstract: The photo-induced rearrangement of 2-benzoyl-3-phenylquinoxaline-1,4-dioxide yielding 1,3- dibenzoylbenzimidazolone (DBBI) is studied by time-resolved fluorescence, UV/vis absorption, and IR spectroscopy. This complex rearrangement occurs on time scales ranging from 0.1 ps up to minutes. Processes within the excited singlet state(s) (0.1–1 ps) are followed by a multi-phasic depletion of the fluorescent states (time constants of 1–200 ps). During that depletion both a triplet state and a precursor of the photo-product are populated. In absence of oxygen the triplet state decays in 8 mus. It does not participate in the formation of the photoproduct. A process with a time constant of 77 min terminates the product formation. It can be assigned to a hindered rotation of the benzoyl residues in DBBI. BMO authors (in alphabetic order): Elina Borysova Thorben Cordes Peter Gilch Bjoern Heinz Nadja Regner Gerald Ryseck  WWW-Version |