Direct kinetic measurement of the reaction of the simplest Criegee intermediate with water vapor

Abstract

Double trouble for Criegee intermediates Atmospheric ozone reacts with unsaturated hydrocarbons to form unstable compounds called Criegee intermediates. Only recently did a reliable method emerge to make and study these compounds in the laboratory, and they didn't seem to react with water. Now, Chao et al. show that the simplest Criegee intermediate, CH 2 OO, does in fact react very rapidly with pairs of water molecules (see the Perspective by Okumura). Earlier studies may have missed this result because they were conducted at low pressure, where water dimers are scarce, or because they monitored downstream processes. The new rate measurements imply that reactivity with atmospheric water pairs is a major decay channel for Criegees. Science , this issue p. 751 ; see also p. 718