"Impact of Vibrational Excitation on the Kinetics of a Nascent Ketene"Thomas Schmierer, Wolfgang J. Schreier, Florian O. Koller, Tobias E. Schrader, Peter Gilch
Phys. Chem. Chem. Phys. 11 (2009) 11596
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 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 60 ps and the rapid and the slow phases of the decay start to merge.
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