The reaction of acetylperoxy radicals with NO2

Acetylperoxy radicals were produced by the flash photolysis of chlorine in the presence of acetaldehyde and oxygen. By adding various concentrations of nitrogen dioxide, the rate constant for the reaction producing PAN was measured to be k4 (153 Torr) = (2.29 ± 0.05) × 109 L/mol s. The effect of pressure has been studied over the range 76–612 Torr and the data fitted to a fall‐off curve with k 4∘ = 1.85 × 1013 L2/mol2 s. and k 4x = 3.67 × 109 L/mol s. With a calculated value of the dissociation constant, k −4∘ = 268 L/mol s and of the equilibrium constant, K4 = 1.04 × 1012 L/mol, the expected strong collision value for k 4∘ is 2.79 × 1014 L2/mol2 s. The ultraviolet absorption spectrum of PAN has been characterized in the range 205–260 nm.