Kinetics and dynamics of nitrogen adsorption on Ru(001): evidence for direct molecular chemisorption

The experimentally determined value of the molecular chemisorption probability, S0 has an interesting dependence on incident kinetic energy, Ei, and incident angle, θi, for the N2/Ru(001) system. An increase in the value of S0 was observed at θi = 60° as Ei was increased from 0.2 to 0.4 eV providing evidence for a direct, activated, mechanism for molecular chemisorption. A simple model of the direct mechanism for high kinetic energy adsorption combined with a hard-cube model to describe trapping-mediated chemisorption at low kinetic energies can account qualitatively for the angular dependence at all incident energies.