Multiphase Chemistry of N2O5, ClNO2, and BrNO2

Abstract

The uptake kinetics of N2O5 were studied with the droplet train technique as a function of temperature between 262 and 278 K on different aqueous solutions. No pronounced temperature dependence was observed, and the average uptake coefficient in this temperature range is 0.018 ± 0.003. When interacting with salt solutions (i.e., NaCl, NaBr, or NaI), N2O5 contributes to the formation of ClNO2 and BrNO2. The multiphase chemistry of these nitryl compounds was further investigated using the wetted-wall technique as a function of temperature between 275 and 293 K on different aqueous solutions. The uptake coefficients are reported for both species, and no distinct temperature dependence was observed. Their uptake rate was efficiently enhanced by the presence, in the aqueous phase, of halogenides ions. When reacting with Br- or I-, both nitryl compounds deliver to the gas phase the molecular form of the halogen, i.e., Br2 or I2. A reaction scheme potentially explaining these observations is presented and its importance for the sea-salt aerosol chemistry is discussed.