Photochemistry of SO 2 in the vacuum—U.V. II. Luminescence studies

Abstract

The photolysis of SO 2 in H 2 has been studied at 147 nm (xenon line) and at 116.5 – 123.6 nm (krypton lines). Chemiluminescent reactions of photofragments lead to the observation of the fluorescence of SO 2 (xenon lamp), OH(A → X) emission (xenon and krypton lamps), S 2(B → X) and SO(B → X) radiative transitions (krypton lamp). The SO(A → X) emission observed with the krypton lamp is attributed to the photodissociation of SO 2 at 116.5 nm (second krypton line). The phosphorescence (a → X) of SO 2, and not its fluorescence, is obtained only on irradiation with the krypton lamp and it is interpreted as the result of internal conversion from the excited state (singlet or more probably triplet) to the emitting first triplet state. The quantum yield for SO 3 formation is shown to be Π ⩽ 0.4 at 123.6 nm. The primary photodissociation processes giving S( 1D or 3P) + O 2 are more important with krypton lines than with the xenon line.