Atmospheric Chemistry and Physics
www.atmos-chem-phys.net
1680-7316
1680-7324
5
9
2005
10.5194/acp-5-2395-2005
http://www.atmos-chem-phys.net/5/2395/2005/
http://www.atmos-chem-phys.net/5/2395/2005/acp-5-2395-2005.html
http://www.atmos-chem-phys.net/5/2395/2005/acp-5-2395-2005.pdf
2395
2402
2005-09-19
Kinetic isotope effects in the gas phase reactions of OH and Cl with CH<sub>3</sub>Cl, CD<sub>3</sub>Cl, and <sup>13</sup>CH<sub>3</sub>Cl
A. A. Gola
B. D'Anna
K. L. Feilberg
S. R. Sellevåg
L. Bache-Andreassen
C. J. Nielsen
Department of Chemistry, University of Oslo, P.O.Box 1033 Blindern, 0315 Oslo, Norway
Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
permanent address: Department of Physical Chemistry, Medical University of Wroclaw, Nankiera, 50–140 Wroclaw, Poland
The kinetic isotope effects in the reactions of CH<sub>3</sub>Cl,
<sup>13</sup>CH<sub>3</sub>Cl and CD<sub>3</sub>Cl with OH radicals and Cl atoms were studied
in relative rate experiments at 298±2 K and 1013±10 mbar. The
reactions were carried out in a smog chamber using long path FTIR detection
and the spectroscopic data analyzed employing a non-linear least squares
spectral fitting method using measured high-resolution infrared spectra as
well as absorption cross sections from the HITRAN database. The reaction
rates of <sup>13</sup>CH<sub>3</sub>Cl and CD<sub>3</sub>Cl with OH and Cl were determined
relative to CH<sub>3</sub>Cl as: <i>k</i><sub>OH+CH3Cl</sub><i>k</i><sub>OH+CH3Cl</sub>/<i>k</i><sub>OH+13CH3Cl}</sub><i>k</i><sub>OH+13CH3Cl</sub>=1.059±0.008,
<i>k</i><sub>OH+CH3Cl</sub><i>k</i><sub>OH+CH3Cl</sub>/<i>k</i><sub>OH+CD3Cl</sub><i>k</i><sub>OH+CD3Cl</sub>=3.9±0.4, <i>k</i><sub>Cl+CH3Cl</sub><i>k</i><sub>Cl+CH3Cl</sub>/<i>k</i><sub>Cl+13CH3Cl</sub><i>k</i><sub>Cl+13CH3Cl</sub>
=1.070±0.010
and <i>k</i><sub>Cl+CH3Cl</sub><i>k</i><sub>Cl+CH3Cl</sub>/<i>k</i><sub>Cl+CD3Cl</sub><i>k</i><sub>Cl+CD3Cl</sub>=4.91±0.07. The uncertainties given are 2σ from the
statistical analyses and do not include possible systematic errors. The
unexpectedly large <sup>13</sup>C kinetic isotope effect in the OH reaction of
CH<sub>3</sub>Cl has important implications for the global emission inventory of
CH<sub>3</sub>Cl.