Atmospheric evolution of organic aerosol

We report here results of an experimental study of the OH-initiated oxidation of solid organics in the presence of O-2, NOx and H2O, using two kinds of self-assembled organic monolayers (alkane and aromatic), paraffin and pyrene films as proxies for organic aerosol. We show that the OH-initiated oxidation of the alkane surfaces leads to rapid volatilization. The gas-phase products detected include HO2, H2O2, CO, CO2, HCO, CH2O, CH3CHO, CH3OH, and HCOOH. We conclude that volatilization is at least as efficient as wet deposition as a removal process for aliphatic particulates, whereas aromatic particulates show higher stability towards volatilization.