DISSOCIATION OF O2 ON Fe(110)

The initial sticking coefficient for dissociative chemisorption of O 2 on Fe(110) has been measured as a function of translational energy, incidence angle, and surface temperature. Dissociation is activated at translational energies above 100 meV, with the sticking probability rising from 0.26 at low energy to >0.9 for energies above 400 meV. At low energies the sticking probability increases as the surface temperature and the normal component of the momentum are reduced, indicating dissociation proceeds via trapping into a molecular precursor state. The initial saturation coverage at room temperature, calibrated from the ordered LEED phases, is 2.2 monolayers with both the saturation coverage and the uptake kinetics being sensitive to the surface temperature.