Products of Criegee intermediate reactions with NO: experimental measurements and tropospheric implications.

The reactions of Criegee intermediates with NO have been proposed as a potentially significant source of the important nighttime oxidant NO, particularly in urban environments where concentrations of ozone, alkenes and NO are high. However, previous efforts to characterize the yield of NO from these reactions have been inconclusive, with many studies failing to detect NO. In the present work, the reactions of formaldehyde oxide (CHOO) and acetaldehyde oxide (CHCHOO) with NO are revisited to further explore the product formation over a pressure range of 4-40 Torr. NO is not observed; however, temporally resolved and [NO]-dependent signal is observed at the mass of the Criegee-NO 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.