The Triplet State of Ketones in Solution: The Role of the Charge Transfer State in the Quenching of Triplet Acetone by Aromatic Molecules

Abstract

The rate constants for quenching of triplet acetone by a series of halobenzenes have been determined by flash emission technique. Quenching was found to be approximately a hundred times faster than that for triplet benzophenone. For both triplet ketones, quenching did not decrease with the increase in triplet energy difference between ketone and quencher (as expected for normal endothermic triplet energy transfer) and did not correlate with the i.p. of all of the quenchers studied. All of the qualitative features of the quenching results can be simply interpreted in terms of enhanced coupling of the locally excited triplet ketone and quencher states as a result of interaction with the charge transfer state.