Surface-molecule proton transfer: A demonstration of the Eley-Rideal mechanism

Abstract

Hyperthermal molecular DABCO [N(${\mathrm{C}}_2$ ${\mathrm{H}}_4$ ${)}_3$N] is scattered from hydrogen-covered Pt(111). Some of the scattered molecules are protonated at the surface and leave with a kinetic energy which is strongly dependent on the incident energy. This means that proton abstraction is occurring immediately on collision and it serves as a clear demonstration of an Eley-Rideal mechanism. No isotope effect was observed, excluding a tunneling mechanism. The proton transfer shows a threshold energy equal to the difference between the surface work function and the molecular ionization potential. The reaction therefore proceeds via a molecule-surface electron transfer and a subsequent H-atom abstraction.