Kinetics of the reaction of CF₃O with NO

The reaction between CF₃O and NO has been studied by laser flash photolysis/transient diode laser absorption over the range 213 K ≤ T ≤ 353 K. CF₃O was generated by the 193 nm photolysis of (CF₃O)₂. The dominant dissociation pathway is O-O bond fission (Φ ≅ 0.85), but C-O bond breaking occurs to a small extent (Φ ≅ 0.15). A significant fraction of the CF₃O (∼30%) is born with sufficient internal excitation to dissociate into F₂CO and F atoms. The presence of NO leads to additional F₂CO formation. The analysis of this formation rate, as well as the NO loss rate, yields a temperature dependent rate constant of (4.4 ± 1.5) × 10^-11e^(+100±88)/T cm³ s^-1 for the CF₃O + NO reaction. The measured rate constants agree well with previous results based on observations of CF₃O disappearance. They confirm expectations that the reaction yields exclusively the products FNO and F₂CO and that it serves as an efficient stratospheric sink for the CF₃O radical. The reaction between CF₃O and HCl has also been examined, and an upper limit of 2 × 10^-13 cm³ s^-1 has been determined for its rate constant at 295 K. The small rate constant for this reaction relative to the rapid removal of CF₃O by NO severely limits the possibility that hydrofluorocarbons contribute to stratospheric ozone depletion by their CF₃O degradation product liberating chlorine atoms from HCl.