Photolysis of glyoxal at 193, 248, 308 and 351 nm

The UV photochemistry of glyoxal in nitrogen has been investigated by employing excimer laser photolysis at 193, 248, 308 and 351 nm in combination with cavity ring-down spectroscopy. The HCO radical was a photofragmentation product with yields of 0.42 ± 0.21, 0.53 ± 0.24, 0.69 ± 0.29, and 1.5 ± 0.6 at 193, 248, 308 and 351 nm. The larger than unity HCO yield at 351 nm suggests the photolysis channel (CHO)2 + hv (351 nm) → 2 HCO. The decrease in HCO yields at higher photolysis photon energies is attributed to the opening up of additional glyoxal photolysis pathways.