A COMPARATIVE-STUDY OF THE CHEMISORPTION OF ETHENE ON 3 METAL-SURFACES - NI(111), PD(111) AND PT(111)

The chemisorption of ethene on three metal surfaces, Ni(iii), Pd(111) and Pt(111), has been studied by an approximate molecular orbital method: extended Huckel calculations within a tight-binding formalism. The overlap population between individual fragment molecular orbitals (FMO) of the adsorbate and each atomic orbital (AO) or atom of the surface can be partitioned accurately. The relative importance of each FMO to the ethene-metal bonding can the be assessed. Moreover, interaction diagrams can be constructed to describe the adsorbate-surface bonding. The preferred adsorption sites determined by our calculations are supported by the vibrational data obtained by electron energy loss scattering. The activation energy for the transformation of pi-bonded ethene to di-sigma-bonded adsorbate on Pt(111) has been estimated.