Extremely Fast Reaction of Criegee-Intermediate-Derived Organic Peroxides with NO ₂ at the Air–Liquid Interface

The heterogeneous chemistry of NO_<i>x</i> in the atmosphere remains incompletely understood, and NO_<i>x</i> potentially undergoes chemical reactions with organic peroxides (OPs) in the condensed phase. Here, we present a new experimental approach to directly quantify apparent rate constants (<i>k</i>_app) for reactions of Criegee-intermediate-derived OPs with NO₂ and NO at the air-liquid interface. Using OPs derived from representative terpenoids (α-pinene,<i>d</i>-limonene, β-caryophyllene, and α-terpineol), we show that all OPs react extremely rapidly with NO₂, while exhibiting much lower reactivity toward NO. The measured interfacial rate constants for OP + NO₂ are approximately 3 orders of magnitude larger than those for OP + NO, consistent with preferential NO₂ adsorption at the interface. At atmospherically relevant NO₂ levels (1 ppb), OP lifetimes are reduced to the subsecond time scale, indicating that NO₂ can dominate OP removal under elevated NO_<i>x</i> conditions. These findings highlight the importance of interfacial NO₂ chemistry in controlling the fate of Criegee-intermediate-derived OPs in the atmosphere.