Journal of Physical Chemistry A, Vol.114, No.45, 12052-12061, 2010
ClO Radical Yields in the Reaction of O(D-1) with Cl-2, HCl, Chloromethanes, and Chlorofluoromethanes
Absolute ClO radical product yields in the gas-phase reactions of O(D-1) with Cl-2, HCl, CCl4, CHCl3, CH3Cl2, CH3Cl, CF2Cl2, CF3Cl, CHFCl2, and CHF2Cl are reported. Product yields were measured using pulsed-laser photolysis of O-3 to produce O(D-1) in the presence of excess reactant combined with dual wavelength differential cavity ring-down spectroscopic detection of the ClO radical. ClO radical absorption cross sections for the A(2)Pi(nu = 10) <-- X-2 Pi(nu = 0) transition hand head near 280 nm were determined between 200 and 296 K as part of this work. The ClO product yields obtained at room temperature were Cl-2 (0,77 +/- 0.10), HCl (0.20 +/- 0.04), CCl4 (0.79 +/- 0.04), CHCl3 (0.77 +/- 0.04), CH2Cl2 (0.73 +/- 0.04), CH3Cl (0.46 +/- 0.06), CFCl3 (0.79 +/- 0.04), CF2Cl2 (0.76 +/- 0.06), CF3Cl (0.82 +/- 0.06), CHFCl2 (0.73 +/- 0.05), and CHF2Cl (0.56 +/- 0.03), where the quoted error limits are 2 sigma of the measurement precision. ClO product yields in the O(D-1) + Cl-2 and CFCl3 reactions were found to be independent of temperature between 200 and 296 K. within the precision of the measurements. The absolute ClO yields obtained in this study are compared with previously reported values determined using relative and indirect methods.