The reaction bctwcen nitric oxide and vibrationally excited ozone was studied in a fast flow reactor by monitoring the visible emission from electronically excited NO;. The antisymmetric mode (us) of O3 was excited with a Q-switched 9.6 I.tm CO2 laser, and a laser-induced signal was detected, with a rise rate constant of (4.0 i-0.5) X 10" cm3/mole set and a decay rate constant of (1.1 t 0.1) X 10" cm3/mole WC for an NO-rich mixture. The latter was unaffected by addition of large amounts of He or Ar, indicating that the signal was not a thermal effect. Most of the measurements were made at 350ยฐK; however, the He and Ar dilution results suggest that the enhanced reaction rate is not very sensitive to temperature.
In order to explain the observed rise times, it was necessary to postulate an intermediate step prior to the chemical reaction. A model which is consistent with our data has energy transferred from q to q (the bending mode) at a rate of (2.9 f 0.5) X 10" cm3/molc set for NO and a rate of (1.1 + 0.2) X 10" cm3/mole set for He. According to this model, the rate constant for the reaction of NO with 03 (vz = 1) producing vibrationally excited ground state NOI, NO + Of (010) : NOI + O2 , is (1.5 f 0.2) X 10 I1 cm3/mole set, and the relative rate for the reaction of 03 (~2 = 1) and 03 (~2 = 0) with NO was estimated to be k3(l)/k3 (0) = 22.