INSITU STUDY BY SEELFS OF THE 1ST STAGES OF THE EPITAXIAL-GROWTH OF PALLADIUM CLUSTERS ON MGO(100)

Palladium clusters with a mean diameter of 2 nm were grown by condensing in UHV an atomic beam of Pd on an MgO(100) surface cleaved in UHV. The structure of the MgO surface was characterized in situ by SEELFS before and after the growth of the clusters. From electron diffraction the Pd clusters are perfectly epitaxied on the MgO surface. By looking at the O K and Mg K edges the bare surface did not show evidence of a relaxation. After the growth of the clusters the radial distribution functions (RDFs) from the O K and Mg K edges are modified. By the comparison of these RDFs with different structural models of the interface, it has been shown that the Pd clusters are accommodated on the MgO lattice with the Pd atoms on top of the Mg ions. Therefore it is concluded that pseudomorphism is the origin of the dilatation of the Pd clusters epitaxially grown on MgO.