Quantum yields of CO2 and SO2 formation from 193 nm photo-oxidation of CO in a sulfuric acid aerosol

The measured quantum yield of CO2 is 1.2% for acid strengths in the range 80–100 wt.% under conditions in which the yield varies linearly with the average laser power and is independent of the CO flow. The yield of SO2 is highly variable and may be either positive or negative. These observations lead us to discard our previously postulated mechanism in favour of one involving the production of atomic oxygen in the primary photolysis step. The highly variable and negative yields of SO2 are accounted for by postulating the formation of varying amounts of peroxysulfuric acid in the irradiated droplets.