Cavity ring-down spectroscopic study of acetaldehyde photolysis in the gas phase, on aluminum surfaces, and on ice films

We have studied acetaldehyde photolysis in the gas phase (243 and 293 K), on aluminum surfaces (243 K), and on ice films (243 K), by employing 308 nm excimer laser photolysis combined with cavity ring-down spectroscopy. The HCO radical is a product of acetaldehyde photolysis under each of these conditions. The HCO radical quantum yields from the gas-phase photolysis of acetaldehyde are 0.87 +/- 0.11 and 0.91 +/- 0.10 at 243 and at 293 K, respectively, where errors quoted represent 1 sigma measurement uncertainty. The HCO quantum yields from acetaldehyde photolysis on aluminum surfaces and on ice films are 0.86 +/- 0.32 and 0.47 +/- 0.36 at 243 K, where errors quoted represent 2 sigma measurement uncertainty. The feasibility of using cavity ring-down spectroscopy to study surface photochemical processes has been demonstrated. (c) 2006 Elsevier B.V. All rights reserved.