Reactivity of the (1? g )2 and 1? g states of oxygen produced by direct laser excitation

Abstract

The (1Δg)2 and 1Δg states of oxygen have been produced by direct laser (He–Ne and Nd–YAG) excitation of oxygen at high pressure dissolved in a suitable solvent, and their reactivities with various substrates investigated. For 9,10-dimethylanthracene and 1,3-diphenylisobenzofuran, the quantum yields for (1Δg)2 excitation are, within experimental error, twice those for 1Δg excitation. In the reactions of 1Δg oxygen with 9,10-dimethylanthracene and tetraphenylcyclopentadienone, both chemical reaction (rate kr) and physical quenching (rate kq) are observed. For 9,10-dimethyl-anthracene, kq/kr∼0.6, and for tetraphenylcyclopentadienone kq/kr∼1.7. With 1,3-diphenyl-isobenzofuran, kq/kr is in the range 0–1. It is shown unambiguously that 1Δg oxygen reacts with two tertiary amines, triethylamine and tropinone, in addition to being quenched. For triethylamine, kq/kr∼11.