Low-Temperature kientics of reactions of the OH radical with propene and 1-butene studied by a pulsed laval nozzle apparatus combined with laser-induced fluorescence

摘要

The kinetics of the reactions of the OH radical with propene and 1-butene are studied at T=103K.The low-temperature environment is provided by a pulsed Lava nozzle supersonic expansion of nitrogen with admixed radical precursor and reactant gases.The gas number density and temperature distributions in the 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 A~2#sum#~+-X~2II_i transition.For the kientic 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 mwasured at T=103K to be (0.81+-0.18)*10~(10) and (1.24+-0.27)*10~(-10) cm~3 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.