KINETIC-STUDIES OF OH REACTIONS WITH H2O2, C3H8 AND CH4 USING THE PULSED-LASER PHOTOLYSIS - LASER-INDUCED FLUORESCENCE METHOD

The rate coefficients for the reactions of OH with H2O2, C3H8 and CH4 have been determined using a newly built pulsed laser photolysis-laser induced fluorescence (PLP-LIF) apparatus. While, the reaction of OH w ith H2O2 was studied at room temperature, the rate coefficients of OH reactions with CH4 and C3H8 were measured over a large range of temper ature at P = 100 Torr of helium. The measured rate constant for the re action of OH with H2O2 was k1 = (1.75 +/- 0.20) X 10(-12) cm3 molecule -1 s-1. The kinetic data for C3H8 (k2) and CH4 (k3) were used to deriv e the Arrhenius expressions (in cm3 molecule-1 s-1) : k2 = (9.81 +/- 0 .11) X 10(-12) exp[-(650 +/- 30)/T] between 233 and 363 K, and k3 = (2 .56 +/- 0.53) x 10(-12) exp[-(1765 +/-146)/T] between 233 and 343 K. T he results obtained for k1 and k2 provide a validation of the PLP-LIF technique and those for k3 SUPPort the low value recently published, w hich has an important atmospheric impact.