Reaction of OH + NO2 + M: Kinetic evidence of isomer formation

The objective of this paper is twofold: First, we present new experimental data on the reaction of OH + NO2 at room temperature, which show that the results obtained earlier in our laboratory (see []) are about 30% too high. Secondly, we provide direct experimental evidence, that peroxynitrous acid (HOONO) is formed in the title reaction: At temperatures between 430 and 480 K we observe bi-exponential OH loss over the complete pressure range (1–130 bar) studied, which certainly supports the formation of the HOONO isomer. We determined the equilibrium constant for the OH + NO2 ⇔ HOONO reaction as a function of temperature and extracted from a 3rd-law analysis an O–O bond energy in the HOONO of ΔH°(0 K) = 83 ± 1 kJ mol−1.