Methylperoxo radical

CH3CO (it is not RO but a carbon radical CO) adds O2 (see 5.64) and produces PAN (5.259) but also in a competitive reaction as RO2 radical it oxidizes NO and afterwards decomposes (from the methylperoxo radical CH3O2 finally formaldehyde is given). 

As for other peroxo radicals, it can transfer O onto other dissolved species (NO NO2) and then decompose them (finally, the methylperoxo radical forms HCHO). 

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