A theoretical investigation on the atmospheric degradation of the radical: reactions with NO, NO, and NO.

The radical is the key intermediate in the atmospheric oxidation of benzaldehyde, and its further chemistry contributes to local air pollution. The reaction mechanisms of the radical with NO, NO, and NO were studied by quantum chemistry calculations at the CCSD(T)/CBS//M06-2X/def2-TZVP level of theory. The explicit potential energy curves were provided in order to reveal the atmospheric fate of the radical comprehensively. The main products of the reaction of with NO are predicted to be , CO and NO. The reaction of with NO is reversible, and its main product would be CHC(O)ONO which was predicted to be more stable than PAN (peroxyacetyl nitrate) at room temperature. The decomposition of CHC(O)ONO at different ambient temperatures would be a potential long-range transport source of NO in the atmosphere. The predominant products of the reaction are predicted to be CHC(O)OH, CHC(O)OH, O and O, while HO˙ is of minor importance. So, the reaction of with would be an important source of ozone and carboxylic acids in the local atmosphere, and has less contribution to the regeneration of HO˙ radicals. The reaction of with NO should mainly produce , CO, O and NO, which might play an important role in atmospheric chemistry of peroxy radicals at night, but has less contribution to the night-time conversion of ( and RO˙) to ( and HO˙) in the local atmosphere. The results above are in good accordance with the reported experimental observations.