Valence changes of Sm atoms adsorbed on Mo (2 1 1) surface

Abstract Adsorption of Sm thin layers on the Mo (2 1 1) face was investigated by using Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), X-ray photoemission spectroscopy (XPS) and changes of the work function measurements (Δ ϕ ). The layer growth mode and the valence change of Sm atoms were determined. The Sm layer growth mode is layer-by-layer, at least to 3 ML, followed by the crystallite growth. It was found out that for θ θ  = 1 ML, 11% of Sm atoms are divalent, and 89% trivalent. The second layer is composed of only divalent atoms. The first two layers have different surface densities, namely 6.15 × 10 14  atoms/cm 2 for the first layer, and 5.56 × 10 14  atoms/cm 2 for the second. Divalent Sm atoms creating the second layer form islands with the p(3 × 1) structure observed by LEED and STM.