Shock tube study of the rate constants for H + O₂+ M → HO₂+ M (M = Ar, H₂O, CO₂, N₂) at elevated pressures

The rate constants for the reaction H + O₂+ M→HO₂+ M were investigated at elevated pressures from 12 to 33 atm using ignition delay time (IDT) measurements behind reflected shock waves in H₂/O₂/M mixtures with different collision partners M = Ar, H₂O, N₂ and CO₂. The temperature and pressure ranges where the rate constants of the reactions H + O₂+ M→HO₂+ M and H + O₂- > OH + O dominate the IDT sensitivity were selected as optimum test conditions using the detailed H₂/O₂ mechanism of Hong et al. (2011). The current study thus provides a quantitative and relatively direct method for determining the rate constants for H + O₂+ M→HO₂+ M using simple IDT measurements. The rate constants found are consistent with earlier studies, but with reduced uncertainties.