Probing reaction dynamics at metal surfaces with H2 diffraction

We review recent experimental and theoretical work aimed to understand the reaction dynamics of hydrogen molecules at metal surfaces. Diffraction experiments and calculations using ab initio determined six-dimensional potential energy surfaces were carried out on several single-crystal surfaces: NiAl(110), Pt(111), Pd(111) and Pd(110). We discuss the general trends observed in the energy range studied (20-150 meV) when going from non-reactive to very reactive surfaces as well as specific features of the dynamics which can be seen in diffraction studies.