Real time observation of the photo-Fries rearrangement.
The photo-Fries rearrangement of 4-tert-butylphenyl acetate dissolved in cyclohexane is investigated by two-color femtosecond pump probe spectroscopy. The spectral transmission changes are characterized in the visible and ultraviolet spectral region and allow for the first time to temporally resolve the primary reaction steps. We find that the photoinduced homolytic cleavage of the CO bond occurs within 2 ps and that the geminate recombination of the generated radical pair to the intermediate substituted cyclohexadienone takes 13 ps. The experimental results support a model in which the initial reaction proceeds from the originally excited pipi(*) state via a barrier to a dissociative pisigma(*) state.
Lehrstuhl für BioMolekulare Optik, Sektion Physik, Ludwig-Maximilians-Universität, Oettingenstrasse 67, 80538 München, Germany. stefan.lochbrunner@physik.uni-muenchen.de
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Zissler
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Riedle
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