Mechanism of S2 chemiluminescence in the reaction of hydrogen atoms with hydrogen sulphide

Abstract

Ground-state sulphur atoms were generated in a discharge flow system by the rapid reaction between H and H₂S: H + H₂S = H₂+ HS (1), H + HS = H₂+ S (2) The resulting chemiluminescence by the B³Σ^–_u state of S₂ is shown to arise (a) by two-body combination of S atoms into level v′= 10; (b) by three-body recombination into lower levels: S(³P)+ S(³P)+ M = S^*₂(B³Σ^–_uv′⩽9)+ M (3), S^*₂= S₂(X³Σ^–_g)+hv(4), S^*₂+ M = S₂+ M (5) with k₃=(1.0 ± 0.2)× 10¹⁵ cm⁶ mole^–2 sec^–1 and k₄/k₅= 2.0 × 10^–7 mole cm^–3 for M = Ar at 298°K; also D(S—S)= 101.7 ± 0.4 kcal/mole. The mechanism of the sulphur-catalyzed heterogeneous recombination of hydrogen atoms is studied and discussed.