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 [ref. 1 and 2]) 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 DeltaDdegrees (0 K) = 83 +/- 1 kJ mol(-1).