Formation and fate of ClNO2 from the reaction between N2O5 and NaCl solution and its possible kinetic mechanism, a contribution to subproject HALIPP

Uptake of N2O5 by aerosols, clouds and fog is believed to be the main tropospheric sink of NOx and is known to form HNO3 that is subsequently removed by wet and dry deposition. Our smog chamber experiments, in the presence of wet NaCl aerosol, showed that gaseous N2O5 is transformed to ClNO2 and HNO3 at almost stoichiometric ratio {1-3}. The observed ratio between these products as a function of the Cl- concentration in the aerosol cannot be explained from simply two competing reactions. Results from wetted-wall flowtube experiments at various Cl- and NO3- concentrations enable us to suggest a detailed reaction mechanism.