Resonance absorption measurements of atom concentrations in reacting gas mixtures. IX. Measurements of O atoms in oxidation of H2 and D2

Resonance absorption spectroscopy has been used to measure oxygen atom concentrations in shock heated H2-O2-Ar and D2-O2-Ar mixtures at 1000 to 25000K. From data on rich and stoichiometric mixtures we found (mole-1 cm3 s-1 for reaction 3 and mole-2 cm6 s-1 for reaction 5) H + O2 → OH + O; K3 = 1.2E14 exp(-67.4kJ/RT); H + O2 + Ar → HO2 + Ar; K5 = 4.5E14 exp(4.2kJ/RT); D + O2 → OD + O; K/sub 3D/ = 5.8E13 exp(-62.8kJ/RT); D + O2 + Ar → DO2 + Ar; K/sub 5D/ = 2.2E14 exp(4.2kJ/RT). The kinetic isotope effect for reaction 3 was 1.4 at 1500K, while that for reaction 5 was 2.0 in the 1000 to 1200K range. Data from very lean H2-O2-Ar and D2-O2-Ar mixtures are consistent with the rate coefficients (mole-1 cm3 s-1). O + H2 → OH + H; k4 = 4.2E14 exp(-57.5kJ/RT); O + D2 → OD + D; K/sub 4D/ = 1.9E14 exp(-59.6kJ/RT). The isotope effect for reaction 4 from the above equations is 2.6 at 1500K, compared to 1.7 from N2O experiments