Photoinduced aging of tropospheric aerosols: What is more important UV or visible light?

C. GEORGE; B. D'ANNA; M. E. MONGE; R. AMMAR; T. ROSENØRN

Boston

Encuentro; 240th ACS National Meeting & Exposition; 2010

Recent findings confirm the presence of light absorbing organic material (HULIS, biomass burning particles, PAHs) in atmospheric aerosols. The presence of light absorbing material in aerosol particles can allow photosensitised processes to occur. While aquatic photochemistry has recognised several of such processes that accelerate degradation of dissolved organic matter, almost nothing is known thus far about such processes in/on atmospheric particles. Our recent works showed that films and aerosols of humic acids are able to activate efficient conversion of NO2 to HONO and to deplete ozone when the system is irradiated under UV-A and visible light. Therefore near-UV/vis light-absorbing species present in the particulate matter interacting with gas trace gases can initiate a new and potentially important photo-induced heterogeneous chemistry which is presently almost completely unknown and ignored. This contribution will highlight photosensitized reactions are affecting chemical transformations in aerosols by introduce new growth and oligomer formation pathways.