Adsorption of Ethylene on Neutral, Anionic and Cationic Gold Clusters

The adsorption of ethylene molecule on neutral, anionic and cationic gold clusters consisting of up to 10 atoms has been investigated using density-functional theory. It is demonstrated that C2H4 can be adsorbed on small gold clusters in two different configurations, corresponding to the πand di-σ -bonded species. Adsorption in the π-bonded mode dominates over the di-σ mode over all considered cluster sizes n, with the exception of the neutral C2H4−Au5 system. A striking difference is found in the size-dependence of the adsorption energy of C2H4 bonded to the neutral gold clusters in the π and di-σ configurations. The important role of the electronic shell effects in the di-σ mode of ethylene adsorption on neutral gold clusters is demonstrated. It is shown that the interaction of C2H4 with small gold clusters strongly depends on their charge. The typical shift in the vibrational frequencies of C2H4 adsorbed in the πand the di-σ configurations gives a guidance to experimentally distinguish between the two modes of adsorption. To whom correspondence should be addressed †Hokkaido University ‡On leave from: Institute of Physics, St Petersburg State University, 198504 St Petersburg, Petrodvorez, Russia