Peroxy Radical Chemistry and the Volatility Basis Set

Abstract. Gas-phase auto-oxidation of organics can generate highly-oxygenated organic molecules (HOMs) and thus increase secondary organic aerosol production and enable new-particle formation. Here we present a new implementation of the Volatility Basis Set (VBS) that explicitly resolves peroxy radicals (RO 2 ) formed via auto-oxidation. The model includes a strong temperature dependence for auto oxidation as well as explicit termination of RO 2 , including reactions with NO, HO 2 , and other RO 2 . The RO 2 cross reactions can produce dimers (ROOR). We explore the temperature and NO x dependence of this chemistry, showing that temperature strongly influences the intrinsic volatility distribution and that NO can suppress auto-oxidation under conditions typically found in the atmosphere.