| Autor: |
McCoy JC; Department of Chemistry, University of Louisiana at Lafayette, Louisiana, Louisiana 70503, United States., Léger SJ; Department of Chemistry, University of Louisiana at Lafayette, Louisiana, Louisiana 70503, United States., Frey CF; Department of Chemistry, University of Louisiana at Lafayette, Louisiana, Louisiana 70503, United States., Vansco MF; Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States., Marchetti B; Department of Chemistry, University of Louisiana at Lafayette, Louisiana, Louisiana 70503, United States., Karsili TNV; Department of Chemistry, University of Louisiana at Lafayette, Louisiana, Louisiana 70503, United States. |
| Abstrakt: |
Criegee intermediates are important atmospheric oxidants, formed via the reaction of ozone with volatile alkenes emitted into the troposphere. Small Criegee intermediates (e.g., CH 2 OO and CH 3 CHOO) are highly reactive, and their removal via unimolecular decay or bimolecular chemistry dominates their atmospheric lifetimes. As the molecular complexity of Criegee intermediates increases, their electronic absorption spectra show a bathochromic shift within the solar spectrum relevant to the troposphere. In these cases, solar photolysis may become a competitive contributor to their atmospheric removal. In this article, we report the conformer-dependent simulated electronic absorption spectra of two four-carbon-centered Criegee intermediates, methyl vinyl ketone oxide (MVK-oxide) and methacrolein oxide (MACR-oxide). Both MVK-oxide and MACR-oxide contain four low-energy conformers, which are convoluted in the experimentally measured spectra. Here, we deconvolute each conformer and estimate contributions from each of the four conformers to the experimentally measured spectra. We also estimate the photolysis rates and predict that solar photolysis should be a more competitive removal process for MVK-oxide and MACR-oxide (cf. CH 2 OO and CH 3 CHOO). |
