Determination of the structure of disordered overlayers of ethylene on clean and hydrogen-covered Pdð111Þ by low-energy electron diffraction

The surface structure of the disordered overlayer formed by ethylene adsorption on Pdð111Þ at 80 K is determined by low-energy electron diffraction (LEED) from the effects of chemisorbed molecules on the intensity versus beam energy ðI=EÞ variation of the substrate ð1 1Þ Bragg spots. It is shown that ethylene is di-r-bonded on clean Pdð111Þ, where the measured geometry is in agreement with the results of previous density functional theory (DFT) calculations. The structure of a disordered overlayer of ethylene on hydrogen-covered Pdð111Þ at 80 K is also measured using LEED and is found to form a p-bonded species in accord with previous infrared results. 2004 Elsevier B.V. All rights reserved.