A kinetic study of the gas‐phase reactions of OIO with NO, NO2, and Cl2

The kinetics of iodine dioxide (OIO) reactions with nitric oxide (NO), nitrogen dioxide (NO2), and molecular chlorine (Cl2) are studied in the gas‐phase by cavity ring‐down spectroscopy. The absorption spectrum of OIO is monitored after the laser photodissociation, 266 or 355 nm, of the gaseous mixture, CH2I2/O2/N2, which generates OIO through a series of reactions. The second‐order rate constant of the reaction OIO + NO is determined to be (4.8 ± 0.9) × 10−12 cm3 molecule−1 s−1 under 30 Torr of N2 diluent at 298 K. We have also measured upper limits for the second‐order rate constants of OIO with NO2 and Cl2 to be k < 6 × 10−14 cm3 molecule−1 s−1 and k < 8 × 10−13 cm3 molecule−1 s−1, respectively.