Direct measurement of the Criegee intermediate CH2OO in ozonolysis of ethene
Mixtli Campos‐Pineda, Lei Yang, Jingsong Zhang
Abstract
Abstract The transient species produced from reactions of unsaturated hydrocarbons with ozone, carbonyl oxides, termed “Criegee intermediates”, play a key role in tropospheric oxidation mechanisms. Direct observation and characterization of Criegee intermediates in ozonolysis in situ were proven difficult in decades of efforts. Here, we report the direct measurement of the simplest Criegee intermediate, CH 2 OO, from ozonolysis of ethene by cavity ring-down spectroscopy in a flow cell reactor. The transient CH 2 OO is quantified rapidly by near-ultraviolet absorption spectra via its B̃( 1 A′) ← X̃( 1 A′) transition. Time profiles of CH 2 OO produced in ozonolysis under quasi-steady state conditions are observed. These CH 2 OO concentration profiles benchmark the modeling of the ethene ozonolysis reaction network and mechanism, allowing for determination of the yield and various kinetic data of CH 2 OO.