Determination of the state of hybridization of unsaturated hydrocarbons chemisorbed on nickel

The uv photoemission valence orbital spectra of adsorbed acetylene, ethylene, propylene, and benzene on Ni(lll) are compared with gas-phase spectra as well as Hartree-Fock ground-state orbital energies calculated using a self-consistent-field linear-combination-of-atomic-orbitals method for a range of possible hybridizations of the carbon atoms. We conclude that the chemisorption bonding of these unsturated hydrocarbons involves predominantly -d bonding without any significant rehybridization relative to their gas-phase counterparts. © 1976 The American Physical Society.