Pulsed laser photolysis vacuum UV laser-induced fluorescence kinetic study of the gas-phase reactions of Cl(P) atoms with C -C ketones

The gas-phase reactions of Cl atoms with acetone, butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, and cyclopentanone at 295 ±2 K were studied using pulsed laser photolysis vacuum UV laserinduced fluorescence (PLP-LIF) techniques. Cl(P) atoms were produced by photolysis of Cb at 351 nm and monitored by LIF spectroscopy at 134.72 nm (3pP-3p4s transition). Rate coefficients for reactions of Cl atoms with acetone, butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, and cyclopentanone are (2.30 ±0.12) × 10, (4.08 ±0.21) × 10, (1.23 ±0.13) × 10 , (8.87 ±0.92). × 10, (2.08 ± 0.32) × 10, (1.43 ±0.19) × 10 and (1.16 ±0.12) × 10 cm molecule s, respectively. The results for acetone and butanone are consistent with previous studies. The results for 2-pentanone, 3-pentanone, 2-hexanone, and 3-hexanone are approximately a factor of 2-3 higher than those from previous absolute rate studies. Likely explanations for these discrepancies are discussed. Tropospheric lifetimes of ketones with respect to reaction with Cl atoms are estimated and discussed. © 2007 American Chemical Society.