Reaction of Criegee Intermediate with Nitric Acid at the Air-Water Interface

The role of aqueous surfaces in promoting atmospheric chemistry is increasingly being recognized. However, the bimolecular chemistries of Criegee intermediates, which influence the tropospheric budget of OH radicals, organic acids, hydroperoxides, nitrates, sulfates, and particulate material, remain less explored on an aqueous surface. Herein we have employed Born–Oppenheimer molecular dynamics simulations and two-layer ONIOM (QM:MM) in an electronic embedding scheme to study the reaction and the spectroscopic signal of anti-CH3CHOO with nitric acid (HNO3) at the air–water interface, which is expected to be an important reaction in polluted urban environments. The results reveal that on the water surface, the HNO3-mediated hydration of anti-CH3CHOO is the most dominant pathway, whereas the traditionally believed direct reaction between anti-CH3CHOO and HNO3, which results in the formation of nitrooxyethyl hydroperoxide, is only the minor channel. Both reaction pathways follow a stepwise mechanism at the a...