Segregation and interlayer relaxation at the NiPd(111) surface

Abstract

The composition and structure of the NiPd(111) alloy surface are measured using low energy electron diffraction (LEED). The diffracted intensities are analyzed using tensor-LEED methods with the average t-matrix approximation. The major composition results of the study are that the surface is enriched in palladium (≈80% Pd) while the second layer is enriched in nickel (≈28% Pd). No significant structural changes were found, with all measured interlayer displacements being smaller than the corresponding measurement uncertainties. Comparisons of these results are made with literature for other NiPd low-index surfaces, for the well-studied NiPt(111) surface, and with the growing body of theoretical literature for NiPd alloy surfaces.