| Abstract: | The title reaction was studied in a stirred-flow reactor at six temperatures ranging from 228 to 297 K and for pressures near 2 torr. The experiments were performed under O-atom-rich conditions, and the HOONO2 concentration was monitored with a modulated molecular-beam mass spectrometer. O-atom concentrations were measured by titration with NO2 and by monitoring the portion of O2 dissociated in the microwave discharge. A weighted least-squares analysis gives (k ± 1σ) = (7.0 ± 12.2) × 10?11 exp(-3369 ± 489/T) cm3/s, where the uncertainties are 1 standard deviation (six temperatures) the covariance was σAB = 5.97 × 10?8. Due to the possible presence of systematic errors, the uncertainty in the rate constant could be as great as a factor of 2 over the entire temperature range. |
