Products of Criegee intermediate reactions with NO2: experimental measurements and tropospheric implications

The reactions of Criegee intermediates with NO 2 have been proposed as a potentially significant source of the important nighttime oxidant NO 3 , particularly in urban environments where concentrations of ozone, alkenes and NO x are high. However, previous efforts to characterize the yield of NO 3 from these reactions have been inconclusive, with many studies failing to detect NO 3 . In the present work, the reactions of formaldehyde oxide (CH 2 OO) and acetaldehyde oxide (CH 3 CHOO) with NO 2 are revisited to further explore the product formation over a pressure range of 4-40 Torr. NO 3 is not observed; however, temporally resolved and [NO 2 ]-dependent signal is observed at the mass of the Criegee-NO 2 adduct for both formaldehyde- and acetaldehyde-oxide systems, and the structure of this adduct is explored through ab initio calculations. The atmospheric implications of the title reaction are investigated through global modelling.