Journal
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Volume 14, Issue 30, Pages 10391-10400Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/c2cp40294g
Keywords
-
Funding
- Division of Chemical Sciences, Geosciences, and Biosciences
- Office of Basic Energy Sciences
- U. S. Department of Energy
- NERC
- Research Grant Council (RGC) of the Hong Kong Special Administrative Region (HKSAR) [PolyU 5018/09P]
- National Service for Computational Chemistry Software (NSCCS)
- EPSRC (UK)
- IRIDIS High Performance Computing Facility at the University of Southampton
- Leverhulme Trust for an Emeritus Fellowship
- Office of Science, Office of Basic Energy Sciences, Materials Sciences Division, of the U. S. Department of Energy at Lawrence Berkeley National Laboratory [DE-AC02-05CH11231]
- Sandia Corporation
- Lockheed Martin Company, for the National Nuclear Security Administration [DE-AC04-94-AL85000]
- EPSRC [EP/J003921/1] Funding Source: UKRI
- NERC [NE/I014381/1, NE/J009008/1, NE/G01972X/1, NE/I010505/1, NE/I01103X/1] Funding Source: UKRI
- Engineering and Physical Sciences Research Council [EP/J003921/1] Funding Source: researchfish
- Natural Environment Research Council [NE/G01972X/1, NE/I014381/1, NE/I010505/1, NE/I01103X/1, NE/J009008/1] Funding Source: researchfish
Ask authors/readers for more resources
Criegee biradicals, i.e., carbonyl oxides, are critical intermediates in ozonolysis and have been implicated in autoignition chemistry and other hydrocarbon oxidation systems, but until recently the direct measurement of their gas-phase kinetics has not been feasible. Indirect determinations of Criegee intermediate kinetics often rely on the introduction of a scavenger molecule into an ozonolysis system and analysis of the effects of the scavenger on yields of products associated with Criegee intermediate reactions. Carbonyl species, in particular hexafluoroacetone (CF3COCF3), have often been used as scavengers. In this work, the reactions of the simplest Criegee intermediate, CH2OO (formaldehyde oxide), with three carbonyl species have been measured by laser photolysis/tunable synchrotron photoionization mass spectrometry. Diiodomethane photolysis produces CH2I radicals, which react with O-2 to yield CH2OO + I. The formaldehyde oxide is reacted with a large excess of a carbonyl reactant and both the disappearance of CH2OO and the formation of reaction products are monitored. The rate coefficient for CH2OO + hexafluoroacetone is k(1) = (3.0 +/- 0.3) x 10(-11) cm(3) molecule(-1) s(-1), supporting the use of hexafluoroacetone as a Criegee- intermediate scavenger. The reactions with acetaldehyde, k(2) = (9.5 +/- 0.7) x 10(-13) cm(-3) molecule(-1) s(-1), and with acetone, k(3) = (2.3 +/- 0.3) x 10(-13) cm(-3) molecule(-1) s(-1), are substantially slower. Secondary ozonides and products of ozonide isomerization are observed from the reactions of CH2OO with acetone and hexafluoroacetone. Their photoionization spectra are interpreted with the aid of quantum-chemical and Franck-Condon-factor calculations. No secondary ozonide was observable in the reaction of CH2OO with acetaldehyde, but acetic acid was identified as a product under the conditions used (4 Torr and 293 K).
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available