Ordered structures of Yb and Sm on a Mo(110) surface

Abstract

Ordered structures of thin layers of Yb and Sm on a Mo(110) surface have been studied. The discussions are based on results from low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), work function change (Δσ) measurements and thermal desorption spectroscopy (TDS). The main features in LEED, Δσ and thermal desorption spectra upon increasing adsorbate density show many similarities, at least up to a coverage of one monolayer. The first ordered phase is, for instance, of an (n×2) type and starts to grow in islands, and a continuous one-dimensional compression is present at higher coverages in both cases. There are also significant differences between the elements, such as the coverage at which the island formation starts. The coverage of the closely packed monolayer and the behaviour above the monolayer point also differ. The results are discussed with respect to differences in electronic structure and form bases for further investigations relating to the question of the intermediate valence of surface Sm.