Molecular effects in grazing incidence collisions of H₂ with metal surfaces

We have studied the reactive scattering of H₂ under grazing incidence conditions and fast collision energies (0.2–2.0 keV), by means of classical dynamics calculations performed with first-principle six-dimensional potential energy surfaces for H₂/NiAl(110) and H₂/Pd(111). We show that fast light molecules can be used to determine dissociative adsorption probabilities at thermal energies and beyond, from the dissociation threshold up to the saturation limit. The later suggests that this approach is an ideal complement to traditional sticking experiments at thermal energies to determine dissociative adsorption curves up to the saturation limit.