Articles | Volume 15, issue 1
Atmos. Chem. Phys., 15, 495–503, 2015
Atmos. Chem. Phys., 15, 495–503, 2015

Research article 14 Jan 2015

Research article | 14 Jan 2015

Exploring the chemical fate of the sulfate radical anion by reaction with sulfur dioxide in the gas phase

N. T. Tsona1, N. Bork2,1, and H. Vehkamäki1 N. T. Tsona et al.
  • 1Division of Atmospheric Sciences, Department of Physics, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland
  • 2Department of Chemistry, University of Copenhagen, 2100, Copenhagen, Denmark

Abstract. The gas phase reaction between SO4(H2O)n and SO2, n = 0–2, is investigated using ab initio calculations and kinetic modelling. Structures of reactants, transition states and products are reported. Our calculations predict that the SO2SO4(H2O)n cluster ion, which is formed upon SO2 and SO4(H2O)n collision, can isomerize to SO3SO3(H2O)n. The overall reaction is SO2 oxidation by the SO4(H2O)n anionic cluster. The results show that SO4(H2O)n is a good SO2 oxidant, especially at low relative humidity, with a reaction rate constant up to 1.5 × 10−10 cm3 molecule−1s−1. At high relative humidity, instead, the re-evaporation of SO2 from the SO2SO4(H2O)n cluster ion is favoured.

Final-revised paper