Web Release Date: July 26,
Low-Temperature Kinetics of Reactions of the OH Radical with Propene and 1-Butene Studied by a Pulsed Laval Nozzle Apparatus Combined with Laser-Induced Fluorescence
and
JILA, National Institute of Standards and Technology and University of Colorado, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440
Received: March 1, 2001
In Final Form: May 7, 2001
Abstract:
The kinetics of the reactions of the OH radical with propene and 1-butene are studied at T = 103 K. The
low-temperature environment is provided by a pulsed Laval nozzle supersonic expansion of nitrogen with
admixed radical precursor and reactant gases. The gas number density and temperature distributions in the
flow are characterized by both dynamic pressure measurements and laser-induced fluorescence (LIF)
spectroscopy of OH radicals excited in the (1,0) band of the A2
+-X2
i transition. For the kinetic
measurements, the OH radical decay profiles in the presence of reactants are monitored by LIF. The rate
constants of the reactions of OH with propylene and 1-butene are measured at T = 103 K to be (0.81 ± 0.18)
× 10-10 and (1.24 ± 0.27) × 10-10 cm3 molecule-1 s-1, respectively. The observed negative temperature
dependences of the rate constants for both reactions studied by the pulsed Laval nozzle system show good
agreement with both low-temperature and high-temperature kinetic data available in the literature.
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