Ethylene hydrogenation on fcc Co thin films grown on Ni(100) surface

Epitaxial layer-by-layer growth of fcc Co thin films was estimated up to 6 ML on Ni(100) at 300 K by a sharp (1×1) LEED pattern and the breaks in the uptake curves of Ni and Co 2p XP signals. The Co thin films of 1 – 3 ML display the dispersion of the valence band along Γ-K direction in the Brillouin zone in a similar way as the Ni(100) substrate. At 6 ML, the energy band moved upwards in consistent with the shift of the unoccupied states. In closely corresponding to the electronic states of Co thin films, ethane evolution from the reaction of ethylene with pre-saturated hydrogen atoms increased considerably for 1 – 3 ML films and decreased at the coverage of 6 ML.