Dimer binding energies on fcc(111) metal surfaces

Analysis of island density vs. temperature, observed in scanning tunneling microscopy, implies that the binding energy of a self-adsorbed dimer equals 0.11-0.12 of the cohesive energy on Ir(I 11), AI(I 1 1), and Pt(1 11). While ab initio calculations scatter around the experimental results by about 20%, field ion microscopy of Ir(I 11) and Pt(I 11) yields dimer binding energies nearly a factor of three smaller than the corresponding scanning tunneling microscopy results. On the basis of ab initio calculations, these low values are attributed to the neglect of dimer dissociation processes at step edges. (C) 2003 Elsevier B.V. All rights reserved.