Rate coefficients for the OH + HC(O)C(O)H (glyoxal) reaction between 210 and 390 K.

Rate coefficients, k1(T), over the temperature range of 210−390 K are reported for the gas-phase reaction OH + HC(O)C(O)H (glyoxal) → products at pressures between 45 and 300 Torr (He, N2). Rate coefficients were determined under pseudo-first-order conditions in OH using pulsed laser photolysis production of OH radicals coupled with OH detection by laser-induced fluorescence. The rate coefficients obtained were independent of pressure and bath gas. The room-temperature rate coefficient, k1(296 K), was determined to be (9.15 ± 0.8) × 10-12 cm3 molecule-1 s-1. k1(T) shows a negative temperature dependence with a slight deviation from Arrhenius behavior that is reproduced over the temperature range included in this study by k1(T) = [(6.6 ± 0.6) × 10-18]T2[exp([820 ± 30]/T)] cm3 molecule-1 s-1. For atmospheric modeling purposes, a fit to an Arrhenius expression over the temperature range included in this study that is most relevant to the atmosphere, 210−296 K, yields k1(T) = (2.8 ± 0.7) × 10-12 exp[(340 ± 50...