Determination of a (2 root 2 x root 2)R45 degrees structure formed by coadsorption of Li and Mg on a Cu(001) surface

The coadsorption of Li and Mg on Cu(001) at room temperature was studied by low-energy electron diffraction (LEED). A (2 root2 x root2)R45 degrees str ucture was observed and determined by a tensor LEED analysis. It is an orde red mixed phase, in which Mg atoms are located on fourfold substitutional s ites, while Li atoms occupy surface hollow sites, instead of the separation into c(2 x 2)-Mg and (2 x 1)-Li phases formed in the individual adsorption . The (2 root2 x root2)R45 degrees structure is comprised of alternative at omic-rows of substitutional Mg atoms and hollow-site Li atoms aligned along the [010] direction. The stability of this structure is discussed in terms of adsorption energy of Li and Mg atoms and the displacement of surface Cu atoms. (C) 2001 Elsevier Science B.V. All rights reserved.