Gas—Liquid Interactions

The uptake of NO₂ and N₂O₅ by deliquescent NaCl aerosol is investigated in an aerosol smog chamber. While the slow uptake of NO₂ leads to HONO in the gas phase (instead of NOC1), the fast uptake of N₂O₅ leads to C1NO₂ at high yields of almost unity with a high uptake coefficient of (3.2 ± 0.3) x 10−2. The yield of C1NO₂ in the gas phase and its subsequent uptake are studied in wetted-wall flow tube experiments on various solutions containing chloride, nitrate and sulphate. From these experiments, a reaction mechanism is proposed where dissociation of N₂O₅ (in the aqueous phase) into NO₂+ and nitrate is involved.The formation of C1NO₂ from sea-spray aerosol may modify the photo-oxidising capacity of the troposphere by two effects: the lifetime of NO_X is prolonged, and photolytically formed atomic Cl may initiate smog formation soon after sunrise.