Peroxyacetyl nitrate thermal decomposition

Peroxyacetyl nitrate (PAN) undergoes thermal decomposition as follows ... 

The reaction with NO leads to the formation of CO2 and a methyl radical that is oxidized to formaldehyde by reactions (16)-(20). In addition, the oxidation of CH3 regenerates HO c so that the oxidation cycle continues. Association with NO2 produces peroxyacetyl nitrate (PAN). Its lifetime is longer than that of alkylperoxy nitrates, but strongly temperature dependent, ranging from 1 hr at 298 K to 140 d at 250 K. Thus, PAN can be transported over a great distance before undergoing thermal decomposition. Under conditions of lowNOj concentrations acetyl peroxy radicals interact also with HO2 radicals... 

The atmospheric lifetime of peroxyacetyl nitrate with respect to the removal by reaction with OH radicals is estimated to be more than 1 year. The wet and dry depositions are minor removal processes (Roberts, 1990). The thermal decomposition remains the most important loss process up to around 7 km, above which photolysis takes... 

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