The atmospheric chemistry of glycolaldehyde

The chemistry of glycolaldehyde (hydroxyacetaldehyde) relevant to the troposphere has been investigated using UV absorption spectrometry and FTIR absorption spectrometry in an environmental chamber. Quantitative UV absorption spectra have been obtained for the first time. The UV spectrum peaks at 277 nm with a maximum cross section of (5.5 ± 0.7) x 10^-20 cm² molecule^-1. Studies of the ultraviolet photolysis of glycolaldehyde (λ = 285 ± 25 nm) indicated that the overall quantum yield is >0.5 in one bar of air, with the major, products being CH₂OH and HCO radicals. Rate coefficients for the reactions of Cl atoms and OH radicals with glycolaldehyde have been determined to be (7.6 ± 1.5) × 10^-11 and (1.1 ± 0.3) × 10^-11 cm³ molecule^-1 s^-1, respectively, in good agreement with the only previous study. The lifetime of glycolaldehyde in the atmosphere is about 1.0 day for reaction with OH, and >2.5 days for photolysis, although both wet and dry deposition should also be considered in future modeling studies.