Hot-Atom-Mediated Dynamical Displacement of CO Adsorbed on Cu(111) by Incident H Atoms: An Ab Initio Molecular Dynamics Study

Abstract

Nonthermal reactions between gaseous particles and adsorbates on a solid surface commonly exist at the gas–surface interface. Besides the well-known “Eley–Rideal” abstraction reaction, the adsorbate can also be exchanged by the gaseous species via dynamic displacement. We present here the first ab initio molecular dynamics study on the dynamical displacement of CO adsorbed on Cu(111) by incident H atoms. Our results agree reasonably well with the measured displacement cross section, product energy, and angular distributions. More importantly, we explicitly demonstrate that this displacement takes place via a hot atom mechanism. The energetic H atom, accelerated by its chemisorption energy near the surface, could cause CO desorption in various ways accompanied by a surprisingly large-energy dissipation to the surface phonons. As the CO–Cu binding is weakened, the metastable HCO intermediate is possibly formed. This scenario provides a common picture for similar processes with a strong repulsion between the...