Relative Rate Study of the Reactions of Acetylperoxy Radicals with NO and NO₂:  Peroxyacetyl Nitrate Formation under Laboratory Conditions Related to the Troposphere

Abstract

A relative rate study has been performed on the reactions CH 3 C(O)O 2 • + NO 2 + M → CH 3 C(O)O 2 NO 2 + M (1) and CH 3 C(O)O 2 • + NO → CH 3 • + CO 2 + NO 2 (2) in an atmospheric flow system in which the relative yields of CH 3 C(O)O 2 NO 2 (PAN) have been measured as a function of the ratio of reactants [NO]/[NO 2 ]. Over the temperature range 247−298 K, at a total pressure of ∼1 atm, the ratio was independent of temperature, k 1 / k 2 = 0.41 ± 0.03, where the error limits are 2σ. The results are discussed with reference to other relative rate measurements of k 1 / k 2 and to absolute measurements of k 1 and k 2 . The atmospheric implications of the ratio k 1 / k 2 in relation to PAN are briefly considered.