Kinetic study of the reaction of the acetyl radical, CH3CO, with O3 using cavity ring-down spectroscopy

Rate coefficients for the gas-phase reaction CH3CO + O3 → products (1) were measured between 248 and 403 K at 60–200 Torr (N2). Rate coefficients were measured under pseudo-first-order conditions in CH3CO with CH3CO produced by 248 nm pulsed laser photolysis of acetone and monitored using cavity ring-down spectroscopy at 532 nm. Rate coefficients were found to be pressure independent with a weak negative temperature dependence k 1 ( T ) = 1.50 - 0.30 + 0.25 × 10 - 11 exp [ ( 300 ± 50 ) / T ] cm 3 molecule - 1 s - 1 and k1(296 K) = (4.4 ± 0.5) × 10−11 cm3 molecule−1 s−1 where the quoted uncertainties are 2σ and include estimated systematic errors.