Absolute rate coefficient of the reaction of CF2(ã 3B1) with O2 between 288 and 600 K

Abstract

The rate coefficient of the removal of electronically excited CF₂(ã ³B₁) by O₂ (quenching as well as reaction) has been determined for the first time over an extended temperature range (288–600 K). CF₂(³B₁) radicals were generated by pulsed laser photolysis of C₂F₄ at 193 nm and real-time pseudo-first-order decays of the relative CF₂(³B₁) concentration were obtained by monitoring the CF₂(³B₁ → ¹A₁) emission at 570–700 nm. This new CF₂(³B₁)-generation technique allows a straightforward determination of the absolute rate constants. Over the experimental temperature range, the rate coefficient exhibits a simple Arrhenius behaviour with a small activation energy, described by: k_oxygen(T) = (6.7 ± 1.9) × 10⁻¹² exp[−(200 ± 100)K/T] cm³ s⁻¹ molecule⁻¹. No pressure dependence was observed over the 1–20 Torr range using He as the bath gas.