Abstract

Criegee intermediates are reactive intermediates formed in the troposphere principally from the ozonolysis of alkenes. However, Criegee intermediates are short lived and have a low steady-state concentration following production via ozonolysis reactions, making laboratory studies of their chemical behaviour challenging. The advent of photolytic methods to produce Criegee intermediates has facilitated direct studies of their reactivity that have shown some bimolecular reactions of Criegee intermediates to be orders of magnitude faster than previously thought. Several key Criegee intermediate reactions have been investigated utilizing the Sandia Multiplexed Photoionization Mass Spectrometer instrument (MPIMS). When coupled to the tuneable-VUV output of the Chemical Dynamics Beamline at the Advanced Light Source (Lawrence Berkeley National Laboratory), the MPIMS enables acquisition of 3-D datasets (mass, kinetic time, and photoionization energy) allowing direct and unambiguous chemical kinetics and mechanistic studies of Criegee intermediates to be undertaken following their photolytic production. Some recent results from MPIMS studies of Criegee intermediates will be discussed, with particular attention to those pertaining to the generation of highly oxygenated products.