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

Abstract

The (¹Δ_g)₂ and ¹Δ_g 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 (¹Δ_g)₂ excitation are, within experimental error, twice those for ¹Δ_g excitation. In the reactions of ¹Δ_g oxygen with 9,10-dimethylanthracene and tetraphenylcyclopentadienone, both chemical reaction (rate k_r) and physical quenching (rate k_q) are observed. For 9,10-dimethyl-anthracene, k_q/k_r∼0.6, and for tetraphenylcyclopentadienone k_q/k_r∼1.7. With 1,3-diphenyl-isobenzofuran, k_q/k_r is in the range 0–1. It is shown unambiguously that ¹Δ_g oxygen reacts with two tertiary amines, triethylamine and tropinone, in addition to being quenched. For triethylamine, k_q/k_r∼11.