Molecular dynamics at metal surfaces is a fascinating research area. From a theoretical perspective, there are just so many processes of interest: fast molecular scattering, slow electrochemical dynamics (e.g. molecular junctions ), electron transfer, vibrational dissipation, and electron-hole creation. Of course, all of these processes can couple to photons (e.g. photo-electrochemistry ) or to protons (i.e. heterogeneous proton-coupled electron transfer ). From an experimental point of view, all of the above can be studied, even though it is difficult to separate the different effects.