Molecular Mechanisms and Atmospheric Implications of Criegee Intermediate-Alcohol Chemistry in the Gas Phase and Aqueous Surface Environments.

Criegee intermediates and alcohols are important species in the atmosphere. In this study, we use quantum chemistry and Born-Oppenheimer molecular dynamics (BOMD) simulations to investigate the reaction between methanol/ethanol and Criegee intermediates (- or -CHCHOO) in the gas phase and at the air-water interface. Reactions at the interface are found to be much faster than those in the gas phase. When water molecules are available, loop structures can be formed to facilitate the reaction. In addition, nonloop reaction pathways characterized by the formation of hydrated protons, although with a low possibility, are also identified at the air-water interface. Implications of our results on the fate of Criegee intermediates in the atmosphere are discussed, which deepen our understanding of Criegee intermediate-alcohol chemistry in humid environments.