Reaction between OH and CH3CHO Part 1. Primary product yields of CH3 (296 K), CH3CO (296 K), and H (237–296 K)

Abstract

Primary product channels in the reaction of the hydroxyl radical (OH) with acetaldehyde (CH₃CHO) were quantified using the method of pulsed laser photolysis combined with direct detection of acetyl (CH₃CO) and methyl (CH₃) radicals by transient absorption spectroscopy, and H-atoms by resonance fluorescence. Upper limits of 0.03 for a reaction pathway leading to formation of CH₃ + HCOOH at 298 K, and 0.02 for a pathway to H + CH₃C(O)OH (220–298 K) were determined. The major reaction pathway is formation of CH₃CO + H₂O, with a yield of (0.93 ± 0.18). In the course of this study absorption cross-sections of CH₃ and CH₃CO radical were also determined as σ(CH₃) = (3.7 ± 0.3) × 10⁻¹⁷ cm² at 216.4 nm (0.75 nm resolution) and σ(CH₃CO) = (1.4 ± 0.2) × 10⁻¹⁷ cm² at 220 nm.