FTIR STUDIES OF THE ADSORPTION OF CO ON SUPPORTED METALLIC CLUSTERS PD MGO(100)/

Recently, we have evidenced a strong size effect in the adsorption ene rgy of CO on small palladium clusters supported on single crystalline magnesium oxide surfaces. One possible interpretation is the presence of several types of adsorption sites on the metallic clusters. In orde r to investigate more precisely the adsorption of CO, a new experiment has been developed. The main technique is the fast Fourier transform infrared spectroscopy (FTIR) used to measure the stretching vibration frequencies of the adsorbed CO molecules, New results demonstrating th e availability of FTIR to determine adsorption sites of CO on Pd/MgO(1 00) model catalysts are presented. Actually, two distinct absorption b ands are observed, tentatively assigned one to the facets of the clust er and the other to the edges.