Laboratory Studies of Aldehyde Reactions of Atmospheric Importance

Health Research Incorporated/New York State Department Of Health, Menands NY

Investigators

Abstract

The objective of this project is to improve understanding of the kinetics, mechanisms, and products of atmospheric aldehyde (RCHO) reactions. Aldehyde photolysis plays a crucial role in the formation of photochemical smog and regional ozone, via formation of free radicals such as HCO (formyl radicals) and their subsequent conversion into HO2 and OH radicals. Photofragmentation quantum yields of aldehydes exhibit dramatic wavelength dependence in the actinic uv region (>290 nm). Despite the importance of aldehyde photolysis in the chemistry of the troposphere, few wavelength dependent studies of aldehyde photodissociation pathways and quantum yields have been carried out under conditions that can be readily extrapolated to those of the atmosphere. In this proposal, the photolysis of C3 and C4 aldehydes, pinonaldehyde and caronaldehyde (terpenes oxidation products), and glycidaldehyde and glyoxal (aromatic degradation products) will be studied by combining pulsed laser photolysis with cavity ring-down spectroscopy, FTIR, and mass spectrometry for product characterization. In addition, the relationship between aldehyde alkyl group structure and photodissociation quantum yields will be investigated.