Photodissociation of benzaldehyde in the 280-308 nm region

The UV photodissociation of benzaldehyde has been investigated at several w avelengths in the 280-308 nm region by employing excimer or dye laser photo lysis in combination with cavity ring-down spectroscopy. Absorption cross-s ections of benzaldehyde were obtained. The HCO radical was a photofragmenta tion 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 experime ntal 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 degrees N latitude were estimated to be 1.5 x 10(-6) and 1.5 X 10(-5) s(-1), respe ctively. (C) 2000 Elsevier Science B.V. All rights reserved.