Synthesis and structure of ordered stoichiometric Pt3Mn-based surface alloys

By annealing at 500 degreesC thick deposits of Mn on Pt(1 1 1), a chemicall y ordered 2 x 2 surface compound is formed. From a dynamical low energy ele ctron diffraction (LEED) analysis, it consists of a Pt3Mn(1 1 1) bulk-like structure covered by a Pt layer. A different layered structure of alternate d :Pt and Pt3Mn ordered planes is obtained by the same procedure using anne aling temperatures of 650 degreesC. The distinction between the two phases is based in measurements by LEED, STM and XRD. One phase evolves to the oth er via a progressive enrichment of Pt, while keeping the structure and comp osition of the two outermost layers as the temperature increases. (C) 2001 Elsevier Science B.V. All rights reserved.