ACP

Atmospheric Chemistry and Physics

ACP

1680-7324

Copernicus GmbH

Göttingen, Germany

10.5194/acp-1-1-2001

298 K rate coefficients for the reaction of OH with i - C3H7I, n - C3H7I and C3H8

Carl

S. A.

¹ Crowley

J. N.

Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium

Max-Planck-Institut für Chemie, Division of Atmospheric Chemistry, Postfach 3060, D-55020 Mainz, Germany

22 11 2001

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The kinetics of the title reactions were investigated using the laser photolysis - resonance fluorescence method, employing the sequential two-photon dissociation of NO2 in the presence of H2  as the OH source. The 298 K rate constant for OH + C3H8 was found to be (1.15 ± 0.1) × 10-12 cm3 s-1, in excellent agreement with the literature recommendation, and with a separate determination using HNO3  photolysis at 248 nm as the OH source. The 298 K rate constants for OH + n - C3H7I and  i - C3H7I  were measured for the first time and found to be (1.47 ± 0.08) and (1.22 ± 0.06) × 10-12 cm3 s-1, respectively. The errors include an assessment of systematic error due to concentration measurement, which, for the propyl-iodides was minimised by on-line UV-absorption spectroscopy. These results show that reaction with OH is an important sink for  n - C3H7I and  i - C3H7I, which has implications for the reactive iodine budget of the marine boundary layer.