Hollow-site molecular adsorption for NO on Pt(111) and Ni(111): Invalidating vibrational site assignment rules

Dynamical low-energy electron diffraction analyses of ordered structures of NO molecules chemisorbed on Pt(111) and on Ni(111) conclusively yield threefold-coordinated hollow-site adsorption, and reasonable bond lengths. This invalidates long-standing site assignments based on vibrational measurements, calling that approach into question. The results of this study also contrast with the lower-coordinated bridge and top sites found for CO molecules on the same metal surfaces. The NO molecules are oriented close to the surface normal, O end up.