Secondary organic aerosol formation from linalool-derived Criegee intermediates: mechanistic insights into...

The atmospheric oxidation of biogenic volatile organic compounds is a key driver of secondary organic aerosol formation. In this study, a quantum chemical and molecular dynamics investigation of 1,3-dipolar cycloadditions between linalool-derived Criegee intermediates and dimethylketone, both co-products of ozonolysis, is presented. Density functional theory, conceptual DFT descriptors, and transition state theory show that O1-oriented anti-CI pathways proceed with submerged barriers and competitive rate constants up to 10^-10 cm³ molecule^-1 s^-1, while O2 channels are kinetically inaccessible. Classical dynamics reveal rapid nucleation and stable clustering, with water molecules enhancing cohesion through cooperative hydrogen bonding. These results identify cycloadditions with carbonyls as competitive tropospheric sinks for Criegee intermediates and emphasize how emissions from Southern Hemisphere forests may contribute to secondary organic aerosol growth and cloud condensation nuclei formation, with implications for regional climate models.