Structure and formation of surface alloys by adsorption of Li on Al(110)

The surface structures formed by the adsorption of Li on Al(1 1 0) at room temperature have been studied by low energy electron diffraction (LEED) and core-level photoemission spectroscopy (CLS). The Al(1 1 0)-c(2 x 2)-Li str ucture formed by adsorption of one-half monolayer (ML) Li is shown by analy sis of extensive LEED measurements to be an ordered surface alloy. The stru cture contains Li atoms in two-fold substitutional sites formed by the disp lacement of 0.5 ML Al atoms from the first layer of the substrate. This rec onstructive adsorption leads to strong perturbations of the substrate exten ding five layers into the solid. CLS measurements provide insight to the ad sorption geometry at coverages below and above 0.5 ML Li. In particular, it is found that adsorption of Li at coverages above 0.5 ML leads to the form ation of a partially disordered, multilayer surface alloy. (C) 2001 Elsevie r Science B.V. All rights reserved.