Dynamics of “Hot” Oxygen Atoms on Ag(100) Surface upon O₂ Dissociation

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The dynamics of ballistic adsorbates on metal surfaces are not only important for understanding energy dissipation but also of practical relevance in an array of important applications including corrosion and heterogeneous catalysis. In this work, we examine the early dynamics of “hot” O atoms produced by dissociative chemisorption of O2 on a Ag(100) surface, taking advantage of a high-fidelity machine learned high-dimensional potential energy surface based on first-principles data. Our classical trajectory simulations revealed that the experimentally observed large O–O separations (2–4 nm) can only be reached with hyperthermal incident O2. With thermally impinging O2, the calculated separation between the equilibrated O atoms is about 1 order of magnitude shorter (∼0.3 nm). The relatively low mobility of the “hot” O atoms on this surface is attributed to the fast energy dissipation to surface phonons and a relatively high diffusion barrier. In addition, the O atom diffusion exhibits strong anisotropy dictated by the potential energy surface.