Triplet-state chemiluminescence: Acetone T₁ from the decomposition of chemically activated 3,3-dimethyl-4-(N,N-dimethylamino)-1,2-dioxetane

The reaction of O₂(a,¹Δ_g) with N,N-dimethylisobutenylamine has been studied in the gas phase at 298 K, a total pressure of 4 Torr, and an oxygen partial pressure of 0.007-4.0 Torr. The reaction forms a chemically activated dioxetane that decomposes with chemiluminescence (CL). CL spectra were obtained, and deconvolution showed them to consist of acetone T₁ → S₀ and S₁ → S₀ and no other molecular emissions. The T₁ state was efficiently quenched by O₂. The integrated intensity ratio, I(T₁)/I(S₁), was 1.3 at P(O₂) = 0. The T₁ → S₀ spectrum shows its onset at 366 nm and peak intensity at 440 nm.