A Review of Recombination Coefficients of Neutral Oxygen Atoms for Various Materials

Relevant data on heterogeneous surface recombination of neutral oxygen atoms available in the scientific literature are reviewed and discussed for various materials. The coefficients are determined by placing the samples either in non-equilibrium oxygen plasma or its afterglow. The experimental methods used to determine the coefficients are examined and categorized into calorimetry, actinometry, NO titration, laser-induced fluorescence, and various other methods and their combinations. Some numerical models for recombination coefficient determination are also examined. Correlations are drawn between the experimental parameters and the reported coefficients. Different materials are examined and categorized according to reported recombination coefficients into catalytic, semi-catalytic, and inert materials. Measurements from the literature of the recombination coefficients for some materials are compiled and compared, along with the possible system pressure and material surface temperature dependence of the materials' recombination coefficient. A large scattering of results reported by different authors is discussed, and possible explanations are provided.