Reaction mechanisms following gas-surface collisions may differ depending on the site of
impact. On stepped Pt surfaces at least three dissociation mechanisms have been
suggested to occur in parallel. Using supersonic molecular beams and a curved Pt single
crystal, we unravel these site-dependent contributions and quantify absolute reaction cross
sections using these mechanisms' different dependencies on kinetic energy in the range of
0.7 to 13.4 kJ/mol. A sum of three dissociation mechanism probabilities fits our data well and …