Photodissociation of benzaldehyde in the 280–308 nm region

The UV photodissociation of benzaldehyde has been investigated at several wavelengths in the 280–308 nm region by employing excimer or dye laser photolysis in combination with cavity ring-down spectroscopy. Absorption cross-sections of benzaldehyde were obtained. The HCO radical was a photofragmentation product with yields of 0.32±0.05, 0.45±0.05, and 0.29±0.05 at 280, 285, and 308 nm, respectively, where uncertainty reflects experimental scatter. Photolysis rates of benzaldehyde to form HCO for noontime on January 1 and July 1 under clear sky conditions at sea level and 40°N latitude were estimated to be 1.5×10−6 and 1.5×10−5 s−1, respectively.