Adsorption energetics of Ag on MgO(100)

Abstract

This paper reports experimental measurements of the interaction of Ag with MgO(100) thin films grown on Mo(100). Both the adsorption energy and the sticking probability of Ag gas are reported as functions of silver coverage at room temperature. The initial heat of Ag adsorption is \ensuremath{\sim}176 kJ/mol, but increases rapidly with coverage, reaching the bulk silver heat of sublimation of 285 kJ/mol by \ensuremath{\sim}8 ML. At the lowest coverages the sticking probability of silver is \ensuremath{\sim}0.94 and approaches 1.0 with increasing coverage. Auger electron spectroscopy indicates that silver grows as three-dimensional (3D) islands from submonolayer coverages. From the integral heat of adsorption, the adhesion energy of silver to MgO is estimated to be $0.3\ifmmode\pm\else\textpm\fi{}0.3{\mathrm{J}/\mathrm{m}}^{2}.$ The Ag-MgO(100) bond energy is estimated to be \ensuremath{\sim}110 and \ensuremath{\sim}15 kJ/mol within tiny 2D Ag clusters and large 3D Ag particles, respectively.