This award will support collaborative research in atmospheric chemistry between Dr. Anthony J. Hynes, Georgia Institute of Technology and Dr. D.L. Bauch, School of Chemistry, University of Leeds, England. The objective of the proposed research is to study the kinetics and mechanisms of the atmospheric oxidation of dimethyl sulfide using flow discharge techniques. Dimethyl sulfide is known to be emitted by marine organisms and has been suggested to be a precursor to aerosol and cloud formation in marine environments; it is therefore of particular interest for the study of global climate. Experiments will utilize a discharge flow apparatus coupled with laser induced fluorescence and mass spectrometric detection of reactive intermediates and reaction products. Use of calibrated laser induced fluorescence and simultaneous observation of reactant loss and product formation should allow quantitative yields of methyl sulfide radical and sulfur dioxide from the hydroxyl radical initiated oxidation of dimethyl sulfide to be established. Attempts will be made to establish the feasibility of mass spectrometric sampling for the detection of stable reaction products. The project will benefit from the expertise of Dr. Hynes in the development of laser diagnostic techniques in molecular beams, atmospheric sampling and atmospheric kinetics. The British collaborator Dr. Bauch has many years of experience in the application of discharge flow technique to the study of oxygen and hydroxyl radical reactions. The results of this research should contribute to the understanding of the sulphur cycle in global atmospheric chemistry.