Thermal desorption mass spectrometric analysis of organic aerosol formed from reactions of 1-tetradecene and O3 in the presence of alcohols and carboxylic acids

The chemistry of secondary organic aerosol formation from reactions of 1-tetradecene and O-3 in dry air in the presence of excess alcohols and carboxylic acids was investigated in an environmental chamber using a thermal desorption particle beam mass spectrometer. Temperature-programmed thermal desorption of collected aerosol shows that in each reaction two major aerosol products are formed. The more volatile compounds in each pair of products are alpha-alkoxytridecyl or alpha-acyloxytridecyl hydroperoxides, which were identified by comparison of mass spectra with those of standard compounds generated by the corresponding liquid-phase ozonolysis reactions. The formation of organic hydroperoxides in the gas and liquid phases is consistent with a mechanism involving reactions of the alcohols and carboxylic acids with stabilized Criegee biradicals generated in the alkene-O-3 reaction. The less volatile compounds are alpha-alkoxy-alpha'-hydroxyditridecyl or alpha-acyloxy-alpha'-hydroxyditridecyl peroxides (peroxyhemiacetals) formed by reactions of the hydroperoxides with tridecanal, which is generated along with formaldehyde during biradical formation. The vapor pressures of these compounds estimated from their desorption temperatures are similar to 10(-7)-10(-14) Torr. These types of reactions could play a role in atmospheric aerosol nucleation and growth and provide a mechanism for creating fine-particle organic peroxides, which are currently of interest because of their potential for adversely impacting human health.