Paper SS-TuP26
Quantum-Resolved Photodesorption and Photodissociation Studies of Organic Nitrates and Halides on Ice

Tuesday, October 16, 2007, 6:00 pm, Room 4C

Several mechanisms have been proposed for the release of reactive species from organic halides and nitrates on ice during tropospheric ozone depletion episodes at polar sunrise. However, the description of the initial reactions that lead to the formation of precursors for these species remains incomplete because the surface enhanced catalytic effect of ice/snow interfaces is not well understood. Since the photochemical processing of interfaces involving these systems may be an important source of reactive species; we have carried out state resolved studies of photochemical production and release of Br and NO_x from selected organic halides and nitrates adsorbed on ice. Specifically, we utilized resonance enhanced multiphoton ionization to detect the 300 nm photoproduced and desorbed NO and Br (Br^*) from photoexcitation of bromoform and isopropyl nitrate adsorbed on crystalline and amorphous ice. We report cross sections and discuss the potential atmospheric relevance.