The Origin of the Reactivity of the Criegee Intermediate: Implications for Atmospheric Particle Growth

• DOI: 10.1002/anie.201509685
• Publication Date: 2015-12-04T14:10:45Z
• Authors: Evangelos Miliordos; Sotiris S. Xantheas
• Keywords: 0103 physical sciences; 01 natural sciences

AbstractThe electronic structure of the simplest Criegee intermediate, H2COO, is practically that of a closed shell. On the biradical scale (β), where 0 corresponds to the pure closed shell and 1 to a pure biradical, its β value is only 0.10, suggesting that its ground electronic state is best described as a H2C=Oδ+−Oδ− zwitterion. However, this picture of a nearly inert closed shell contradicts its rich reactivity in the atmosphere. It is shown that the mixing of its ground state with the first triplet excited state, which is a pure biradical state of the type H2C.−O−O., is responsible for the formation of strongly bound products during reactions inducing atmospheric particle growth.