Palladium films were grown and characterized in situ by low-energy electron diffraction (LEED) and microscopy in two different regimes: ultra-thin films 2–6 monolayers (ML) thick on Ru(0001), and ~20 ML thick films on both Ru(0001) and W(110). The thinner films were grown at elevated temperature (750K) and were lattice matched to the Ru(0001) substrate. The thicker films, deposited at room temperature and annealed to 880K, have a relaxed in-plane lattice spacing. All the films present a face-centered cubic stacking sequence as determined by LEED intensity versus energy analysis. In all the films, there was hardly any expansion in the surface-layer interlayer spacing. Two types of twin-related stacking sequences of the Pd layers were found on each substrate. On W(110) the two face-centered cubic twin types could occur on a single substrate terrace. On Ru(0001) each substrate terrace has a single twin type and the twin boundaries replicate the substrate steps.

Structure of Ultrathin Pd Films Determined by Low-Energy Electron Microscopy and Diffraction. B.Santos, J.M.Puerta, J.I.Cerda, T.Herranz, K.F.McCarty, J.de la Figuera: New Journal of Physics, 2010, 12[2], 023023