Heterogenous reactions between gas-phase hydroxyl radicals and organic films at the air-water interafce of an atmospheric droplet

Projected climate change is strongly influenced by clouds. The oxidative processing of pollutants in clouds affects droplet size and reflectivity, important climatic effects. Clouds contain naturally occurring lipids forming films on the droplet. Oxidation and removal of this film can prevent precipitation and cause cloud evaporation. Oxidation by gas-phase hydroxyl radical will be contrasted with aqueous phase hydroxyl radical. We will study the kinetics of hydroxyl radicals with a proxy film DSPC at the air-water interface. Specifically, (a) is aqueous oxidation from below the film faster or slower than gas-phase oxidation from above, (b) estimate the atmospheric lifetime of thin film at the air-water interface of aerosol with respect to gas-phase hydroxyl radical oxidation. Provide initial kinetics estimate for further experiment of optically levitated aerosol at LSF-RAL.