High-Pressure Falloff Curves and Specific Rate Constants for the Reactions H + O2 ->//<- HO + O

Article abstract of DOI:10.1021/j100248a033

The recombination reaction H + O2 + M -> HO2 + M is studied by laser flash photolysis in the bath gases M = Ar, N2, and CH4 at pressure between 1 and 200 bar.By extrapolation of the falloff curves, a limiting high-pressure rate coefficient k_infinite = 7.5 x 10^-11 cm³ molecule^-1 s^-1 is derived at 298 K.An analyis of this result in terms of the statistical adiabatic channel model leads to a looseness parameter of α ca. 0.94 Angstroem^-1.The corresponding specific rate constants k(E,J) for dissociation of HO2 are constructed and compared with trajectory calculations.The results are also compared with data on the reaction HO + O -> H + O2 for which a nearly temperature-independent rate constant of 2.8 x 10^-11 cm³ molecule^-1 s^-1 is predicted.An analysis of the limiting low-pressure rate coefficients with respect to energy-transfer properties is made.The results are compared with trajectory calculations of energy transfer of excited HO2.