Temperature effects on the quenching of the triplet state 3Au of biacetyl

Rate data for the quenching of the triplet state ³A_u of biacetyl were determined for a number of collision partners in the gas phase as a function of temperature. Quenching by oxygen and nitric oxide resulted in negative temperature coefficients and the results were interpreted on the basis of the formation of collision complexes. The Arrhenius parameters determined for the reaction of triplet biacetyl molecules with acetaldehyde are an indication that the n,π* configuration of biacetyl behaves like a biradical in the gas phase. The results are consistent with a hydrogen atom abstraction reaction channel.