Kinetics of the nitric oxide-nitrate radical gas-phase reaction NO + NO3 .fwdarw. 2NO2

The rate constant for the reaction NO + NO/sub 3/ ..-->.. 2NO/sub 2/ was measured over the temperature range of 209-414 K by using laser-induced fluorescence detection of NO/sub 3/ in a flow tube reactor. Our recommended results are k(T) - (1.55 +- 0.23) x 10/sup -11/ exp((195 +- 39)/T) cm/sup 3/ molecule/sup -1/ s/sup -1/ for T less than or equal to 300 K and k(T) = (2.95 +- 0.27) x 10/sup -11/ cm/sup 3/ molecule/sup -1/ s/sup -1/ for T > 300 K. These two expressions were required to describe the observed non-Arrhenius behavior of k(T).