Reactive Ion Surface Scattering as an Eley–Rideal Process: A Molecular Dynamics Study into the Abstraction Reaction Mechanism by Low Energy Cs + From Pt(111)

We have employed a classical molecular dynamics simulation for the direct pick‐up reaction of adsorbates by very low energy (1–60 eV) ions scattered at a surface. The system investigated is the reactive ion scattering (RIS) of Cs + with an adsorbate on a Pt(111) surface. The ion–dipole attraction between the projectile and the physisorbed adsorbate drives the abstraction reaction, in which the ion projectile at first collides with the surface to release a substantial amount of its kinetic energy, and subsequently pulls the adsorbate along in the outgoing trajectory. Desorption induced by the ion–dipole attraction is a precursor to the formation of the Cs + –adsorbate product. This Eley–Rideal‐type mechanism must accommodate the inertia of the adsorbate. Consequently, a successful abstraction works well only for low mass adsorbates and slow outgoing Cs + ions. The efficient energy transfer to the Pt(111) surface makes Cs + a better candidate for RIS than lighter projectile ions. Optimal conditions for the efficient RIS abstraction mechanism are found for physisorbed adsorbates with a mass below 32 amu, and for 10 eV Cs + ions at a 45° incidence.