Homogeneous and Heterogeneous Photochemical Reactions Related to Atmospheric Aldehydes and Nitric Acid

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The focus of this renewal award is the continuation of the use of sensitive spectroscopic techniques to determine the wavelength dependent photodissociative quantum yields of gaseous phase aldehydes of interest to atmospheric chemists concerned with air quality and the oxidative capacity of the atmosphere. Knowing the quantum yield of the formyl (HCO) radical of this class of organic atmospheric constituents is of fundamental importance in modeling production of HOx, a key family of oxygen radicals found in the troposphere. As well as extending quantitative laboratory studies to consideration of additional and higher molecular weight aldheydes (glycidaldehyde and glycolaldehyde), further investigations on the oxidation of acetylene, and the photolysis of 2- nitrobenzaldehyde will be undertaken. A final area of investigation concerns the photolysis of nitric acid (HNO3) adsorbed on defined (aluminium) and natural (ice) surfaces, together with a determination of its absorption cross section in the UV (290-310nm) region.Quantitative studies of the gas-phase kinetics of atmospheric chemical reactions serve as the basis for the modelling of air quality in urban and in the natural environments, an important societal need. This research will also contribute to the training and education of women students and postdocs.