title: Photoenhanced uptake of NO2 by pyrene solid films.
abstract: We report uptake kinetics measurements of the heterogeneous reaction of gas phase NO2 with solid films of pyrene. By using a coated flow tube equipped with several near-ultraviolet (UV) emitting lamps (range 300-420 nm), we examined the effect of actinic radiation on the heterogeneous loss kinetics of nitrogen dioxide. With atmospherically relevant concentrations of NO2, (20-119 ppbv), the uptake ranged from below 10(-7) in the dark to 3.5 x 10(-6) under near-UV irradiation. Under illuminated conditions, the uptake coefficient decreased markedly with increasing gas-phase concentration, suggestive of a Langmuir-Hinshelwood-type surface reaction mechanism. The NO2 reactivity was not a function of deposited Pyrene mass or of the relative humidity (in the range 10-89%) and depended linearly on the intensity of illumination. Gas-phase product analysis indicated that approximately 50% of the NO2 loss could be accounted for by HONO and NO release. These experimental results are discussed along with a possible nitration mechanism.
authors.affiliation: University Lyon 1 and CNRS, UMR5256, IRCELYON, Institut de Recherches sur la Catalyse et l'Environnement de Lyon, Villeurbanne, F-69626, France.
authors.forename: Marcello
authors.initials: M
authors.lastname: Brigante
authors.forename: David
authors.initials: D
authors.lastname: Cazoir
authors.forename: Barbara
authors.initials: B
authors.lastname: D'Anna
authors.forename: Christian
authors.initials: C
authors.lastname: George
authors.forename: D J
authors.initials: DJ
authors.lastname: Donaldson