Energy transfer effects of excited molecule production by surface-catalyzed atom recombination

Abstract

Surface-catalyzed atom recombination often yields internally excited molecules. If these molecules are not quenched, by or in the vicinity of the surface, there can be an appreciable reduction in the rate of energy transfer to that surface. To assess the importance of homogeneous and heterogeneous quenching on the wall energy transfer under continuum diffusion conditions, we examine a simple physicochemical model leading to closed-form predictions of the quenching and energy transfer effects and relevant dimensionless parameters. This model, together with available experimental data on the selective production and quenching of electronically excited O₂ molecules during heterogeneous O-atom recombination, are used to estimate: (i) the importance of gas phase and wall quenching in experimental determinations of atom recombination coefficients or the apparent heat of atom recombination at catalyst surfaces, and (ii) the likelihood of appreciable reductions in the aerodynamic heating of hypersonic glide vehicles.