A flash photolysis–resonance fluorescence kinetics study of ground-state sulfur atoms: I. Absolute rate parameters for reaction of S(3P) with O2(3Σ).

The flash photolysis–resonance fluorescence technique has been used to measure the reaction of ground-state sulfur atoms with molecular oxygen as a function of both temperature and total pressure. The most suitable source of S(³P) for this study was found to be COS in the presence of CO₂, as a diluent gas and with the photolysis flash filtered so as to remove all radiation of wavelengths below 1650 Å. Under these conditions, it was found that over the temperature range of 252–423°K the rate data could be fit to a simple Arrhenius-type equation of the form Units are cm³ molec^?1 s^?1. The small A-factor for this reaction, the lack of any pressure dependence, and the direct observation of the production of O(³P) with increasing reaction time suggest that the S(³P) atom attacks the O₂(³Σ) molecule end-on forming SOO which rapidly falls apart to form SO (³Σ) and O(³P).