Elastic strains in silver clusters supported on MgO(100)

This work reports on the change in the silver–silver interatomic distance dAg–Ag as a function of the coordination number for silver clusters supported on MgO(1 0 0) surfaces. Interatomic distances were determined by means of X-ray absorption spectroscopy (XAS) at the silver K-edge. For coordination number lower than 7 (below an average thickness equivalent to 1 ML), dAg–Ag is contracted with respect to the bulk parameter and scales with cluster size. For coordination numbers ranging between 7 and 10 (between 1 and 3 ML), dAg–Ag increases above the bulk value and shows a tendency to match the MgO(1 0 0) substrate. It then relaxes back to the bulk distance. Coordination numbers found herein successfully compare those derived from a model based on grazing incidence small angle X-ray scattering measurements. At low coverage, the XAS data measured by the total electron yield method exhibits diffraction peaks which are consistent with the presence of structurally coherent islands on the MgO substrate.