In situ X-ray absorption measurements of the Cu/Mgo(001) interface

The structure of Cu thin layers deposited on the MgO(001) surface obtained by cleavage in ultra high vacuum has been investigated by in situ X–ray absorption measurements as a function of the metal coverage. By exploiting the polarized nature of the synchrotron radiation it has been possible to measure the Cu-Cu bond length parallel to the substrate surface for coverages in the monolayer range. Extended X-ray absorption fine structure measurements have evidenced a Cu-Cu distance close to that of the bulk metal, resulting from a weak film-substrate interaction irrespective of the copper thickness. Copper oxidation on the MgO surface has not been evidenced. Our results demonstrate that Cu grows in form of cluster and that the film-substrate interaction is weak.