Dynamics of high-barrier surface reactions: Laser-assisted associative desorption of N-2 from Ru(0001)

We have determined the dynamics and energetics of associative desorption of N-2 from Ru(0001) using both an experimental technique, laser-assisted ass ociative desorption, and density functional calculations. These show that N -2 is preferentially desorbed into very high vibrational starts and that th e barriers between gas phase N-2 and adsorbed N atoms increase from 2 to > 3 eV with increasing N coverage on the surface. This experimental technique is found to be quite insensitive to low barrier steps and defects which co mplicate interpretations from other methods of studying high-barrier surfac e reactions.