Rate coefficients for the reaction of methylglyoxal (CH3COCHO) with OH and NO3 and glyoxal (HCO)2 with NO3 R. K. Talukdar1,2, L. Zhu1,2, K. J. Feierabend1,2, and J. B. Burkholder1 1Chemical Sciences Division, Earth System Research Laboratory, NOAA 325 Broadway, Boulder, CO 80305-3328, USA 2Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA
Abstract. Rate coefficients, k, for the gas-phase reaction of CH3COCHO
(methylglyoxal) with the OH and NO3 radicals and (CHO)2 (glyoxal)
with the NO3 radical are reported. Rate coefficients for the OH + CH3COCHO (k1) reaction were measured under pseudo-first-order
conditions in OH as a function of temperature (211–373 K) and pressure
(100–220 Torr, He and N2 bath gases) using pulsed laser photolysis
to produce OH radicals and laser induced fluorescence to measure its
temporal profile. k1 was found to be independent of the bath gas
pressure with k1(295 K) = (1.29 ± 0.13) ×
10−11 cm3 molecule−1 s−1 and a temperature dependence that is
well represented by the Arrhenius expression k1(T) = (1.74 ± 0.20) × 10−12
exp[(590 ± 40)/T] cm3 molecule−1 s−1 where the uncertainties are 2σ and
include estimated systematic errors. Rate coefficients for the NO3 +
(CHO)2 (k3) and NO3 + CH3COCHO (k4) reactions were
measured using a relative rate technique to be k3(296 K) = (4.0 ± 1.0) × 10−16 cm3 molecule−1 s−1 and
k4(296 K) = (5.1 ± 2.1) × 10−16 cm3 molecule−1 s−1.
k3(T) was also measured using an
absolute rate coefficient method under pseudo-first-order conditions at 296
and 353 K to be (4.2 ± 0.8) × 10−16 and (7.9 ± 3.6) × 10−16 cm3 molecule−1 s−1,
respectively, in agreement with the relative rate result obtained at room
temperature. The atmospheric implications of the OH and NO3 reaction
rate coefficients measured in this work are discussed.
Citation: Talukdar, R. K., Zhu, L., Feierabend, K. J., and Burkholder, J. B.: Rate coefficients for the reaction of methylglyoxal (CH3COCHO) with OH and NO3 and glyoxal (HCO)2 with NO3, Atmos. Chem. Phys., 11, 10837-10851, doi:10.5194/acp-11-10837-2011, 2011.