Geometry of acetylene chemisorption on Ni(100) investigated by LEED intensity analysis: The c(2 × 2) structure

Abstract

Results from LEED dynamical calculations performed on the Ni(100) c(2×2)-C 2H 2 structure, produced by adsorption of C 2H 2 at about 273 K and 1.5 L exposure, are reported. Among the several model geometries tried, the most favoured one appears to be a distorted acetylene molecule with the midpoint of the C-C bond (1.20 Å long) placed above the fourfold hollow site at a vertical distance 2.02 Å from the topmost Ni layer and with the C-C axis itself tilted by 50° with respect to the surface normal in the [011] direction. In this geometry the Ni-C distance is 2.2 Å.