Testing realistic environments for metal film growth and aging: chemical insights into the effect of oxygen on Ag/Ag(100)

Abstract We study the effect which exposure to molecular oxygen gas can have on the formation and aging of islands in a submonolayer Ag film on Ag(1 0 0). The technique used is high-resolution low-energy electron diffraction, and the surface temperature is 220–250 K. Oxygen has no discernible effect on the average separation of islands resulting from Ag deposition, implying that molecular oxygen does not interact with atomic Ag as it diffuses and nucleates islands on the terraces. However, oxygen serves to accelerate post-deposition coarsening, causing the average island separation to increase rapidly. We show that atomic, not molecular, oxygen is responsible for this effect. Dissociation of the molecule presumably takes place at kink sites, which are plentiful due to the abundance of island edges in the film, and can be triggered either by electron impact or by thermal activation.