The OH production from the π–π* transition of acetylacetone

Acetylacetone in its enolic form has been found to produce the OH radical as a photofragment after the π–π* transition induced by UV irradiation. The absorption spectrum of the enolic acetylacetone in the supersonic jet, deduced from the OH photofragment excitation spectrum, shows no distinct structures suggesting the very fast decay of the S1 state being followed by the C–O chemical bond dissociation. The photodissociation mechanism is discussed with a qualitative description of the energetics involved.