Surface core level spectroscopy of the Pt25Co75(110) and (100) alloy

Core level photoemission spectroscopy of the Pt 4f 7/2 level is used to investigate the surface and bulk Pt environments in the disordered alloy Pt 25 Co 75 . For the (110) face no Pt is observed at the surface, and only a single Pt bulk site is identified with a chemical shift of 250meV. For the denser (100) face the same bulk site is observed together with a surface peak, corresponding to a surface layer with Pt enrichment. The chemical shift at the surface is weaker than in the bulk