In a breakthrough paper published in the January 13, 2012, issue of Science magazine, researchers from Sandia’s Combustion Research Facility, the University of Manchester, and Bristol University report direct measurements of reactions of a gas-phase Criegee intermediate using photoionization mass spectrometry. (Click here to see a short video of Sandia combustion chemists discussing the research.)
Criegee intermediates—carbonyl oxides—are implicated in autoignition chemistry and are pivotal atmospheric reactants, but only indirect knowledge of their reaction kinetics had previously been available. The article, titled “Direct kinetic measurements of Criegee intermediate (CH2OO) formed by reaction of CH2I with O2,” reports the first direct kinetics measurements made of reactions of any Criegee species, in this case formaldehyde oxide (CH2OO). These measurements determine rate coefficients with key species, such as sulfur dioxide (SO2) and nitrogen dioxide (NO2), and provide new insight into the reactivity of these transient molecules.
The team’s kinetics results indicate a much greater role of carbonyl oxides in tropospheric sulfate and nitrate chemistry than models had assumed, a conclusion that will substantially impact existing atmospheric chemistry mechanisms. This capability breakthrough was funded by the Office of Basic Energy Sciences (BES) within the Office of Science in the U.S. Department of Energy, and conducted using the Advanced Light Source, a scientific user facility supported by BES.
Read the Sandia news release.
Read the article abstract at Science magazine.