Abstract

Criegee intermediates are important species formed during the ozonolysis of alkenes. Recent direct measurement studies have shown that reactions of stabilized Criegee intermediates with various species like SO2 , NO2 and carboxylic acids may have a significant effect in tropospheric chemistry. The simplest and the most abundant Criegee intermediate, CH2OO , is expected to react mainly with (H2O)2 in the atmosphere. However structured Criegee intermediates like (CH3)2COO react slowly with H2O /(H2O)2 and are expected to react with other trace atmospheric species. Results obtained from our time-resolved Cavity Ring-Down Spectroscopy apparatus for reactions of the Criegee intermediates, CH2OO and (CH3)2COO with SO2 and carboxylic acids with various degree of halogenation (HCOOH, CH3COOH , CF3COOH, CF3CF2COOH , CClF2COOH and CHCl2COOH) will be presented, together with a Structure Activity Relationship based on these observations. Structure characterization of the products from these reactions using the Multiplexed PhotoIonization Mass Spectrometry apparatus will also be presented. Preliminary modelling results using global atmospheric model, STOCHEM -CRI, with implementation of these reactions will also be presented.