Energy accommodation during oxygen atom recombination on metal surfaces

The values of the recombination coefficient γ′_O and the fraction β_O of the heat of recombination transmitted to the solid for oxygen atom recombination on Ag, Au, Co, Cu, Fe, Ni, Pt, and W filaments were determined using the flow/diffusion discharge tube method. Values of γ′_O were determined from the atom concentration profile determined with calibrated Wrede-Harteck gauges. Values of β_O were determined using the filament as an isothermal calorimeter. The values of β_O on these oxide covered filaments varied from 0.95 for Ag to 0.07 for Fe. In all cases except Ag and Co, the accommodation of the heat of recombination by the metal was less than 30 %. This result indicated that the oxygen molecules formed in recombination left the surface energetically excited. The values of γ′_O observed were in good agreement with those of previous investigators. Both γ′_O and β′_O showed a weak temperature dependence.