Exposure of Ag/Ag(100) thin films to molecular oxygen $\left({\mathrm{O}}_2\right)$ at 220–250 K is shown to activate low-temperature coarsening of submonolayer island distributions, and a smoothing of multilayer films with “mounded” morphologies. Dissociation of ${\mathrm{O}}_2$ at kink sites populates step edges with atomic oxygen (O), modifying the step-edge energetics, and facilitating Ostwald ripening of film nanostructures. We propose that ripening occurs by “easy” detachment and terrace diffusion of an ${\mathrm{Ag}}_n\mathrm{O}$ species. Cluster diffusion does not play a significant role, contrasting with the O-free system.

• Received 18 March 2002

DOI:https://doi.org/10.1103/PhysRevB.65.193409