Direct Measurement of the Criegee Intermediate CH2OO in Ozonolysis of Ethene

The direct measurement of the simplest Criegee intermediate, CH2OO, from ozonolysis of ethene in a flow cell reactor. The transient CH2OO was quantified rapidly by near-ultraviolet absorption spectra via its B̃(1A′) ← X̃(1A′) transition. Transient time profiles of CH2OO produced in ozonolysis under quasi-steady state conditions were observed for the first time. These CH2OO concentration profiles benchmarked the modeling of the ethene ozonolysis reaction network and mechanism, allowing for determination of the yield and various kinetic data of CH2OO.