Relative rates of reaction of 13C16O, 12C18O, 12C17O and 13C18O with OH and OD radicals

Abstract

A relative rate experiment is carried out for four isotopomers of carbon monoxide (CO) and their reactions with OH and OD radicals. The relative reaction rates of 13C16O, 12Cl8O, 12C17O and 13C18O with OH and OD radicals are measured at 298 +/- 2 K and 1013 +/- 10 mbar. The OH/OD source in the reaction chamber is photolysis of ozone to produce O(1D) in the presence of molecular hydrogen: O(1D) + H2/D2 --> OH/OD + H/D. The relative reaction rates are determined as: k(OH) + 13C16O/k(OH) + 12C18O = 0.98 +/- 0.01, k(OH) + 12C17O/k(OH) + 12C18O = 0.990 +/- 0.008, k(OH) + 13C16O/k(OH) + 13C18O = 0.98 +/- 0.01, k(OD) + 13C16O/k(OD) + 12C18O = 0.99 +/- 0.01, k(OD) + 12C17O/ k(OD) + 12C18O = 1.000 +/- 0.008, k(OD) + 13C16O/k(OD) + 13C18O = 0.98 +/- 0.01. The errors represent 2sigma from the statistical analyses and do not include possible systematic errors. These are novel results for the kinetic isotope effects in the reactions of CO isotopomers with OD radicals. The results for the reactions of CO isotopomers with OH radicals constitute a repeat and a re-analysis of experimental data previously published by this group which have been found to be partly erroneous. This communication serves as a correction to the following paper: K. L. Feilberg, S. R. Sellevåg, C. J. Nielsen, D. W. T. Griffith and M. S. Johnson, Phys. Chem. Chem. Phys., 2002, 4, 4687.