EELFS Determination of Interatomic Distances in Adsorbed Monolayers

Abstract

In a previous work /1/, the chemisorption of carbon on cobalt was successfully investigated with EELFS (Extendend Energy Loss Fine Structure; see, for istance Ref.2). In that study, the nearest neighbor C-Co distance was determined for the Co (11$\overline 2$0)(2×5)-C phase. The aim of the present investigation was to observe possible structural differences when carbon is adsorbed on a quite different substrate plane. Thus, measurements were performed on the (0001) cobalt face, where the atoms are close packed, unlike the (11$\overline 2$0) surface which presents typical zig-zag rows. In a previous study of carbon chemisorption on the (0001) cobalt surface /3/, the formation of a (4×4) superstructure was observed. Since this phase is too complex to be analysed by LEED, we used the EELFS tecnique to evaluate the structural parameters.