Photosensitized reactions on urban film surfaces

Urban films are formed on impervious surfaces in urban environments and are composed of a complex mixture of organic and inorganic compounds. In this thesis, the interaction of film components with light and atmospheric oxidants was investigated. Two separate but related projeci:s were undertaken.;The photoenhancement of the heterogeneous reaction of ozone with solid pyrene films (SF pyrene) and pyrene contained in model urban films (UF pyrene) was examined using a laser-induced fluorescence technique. The ozonation of SF pyrene displayed a moderate light enhancement, the magnitude of which is insufficient to explain previous observations of light-enhanced ozone uptake by solid pyrene surfaces. These results indicate that surface reactivity cannot always be correctly predicted using gas-phase observations.;A suite of environmentally relevant photosensitizers were tested for their ability to enhance nitrate photolysis on model urban film surfaces. No enhancement was observed in the presence of any of the additives.