The Mn 2p core-level photoelectron spectrum of Pd-Mn bimetallic systems on Pd(1 0 0)

It is shown that the Mn 2p spectra of Mn atoms in Pd-Mn bimetallic surface systems formed on Pd(1 0 0) exhibit a satellite, separated 1 eV from the main line, in addition to the 5 eV satellite previously observed for Mn-containing compounds and surface alloys. The main line and the low-energy satellite are both assigned to 2p53d6 final states whereas the 5 eV satellite is associated with 2p53d5 final states. The identification of the two low-binding energy peaks is based on an energy comparison with the Mn 2p→3d X-ray absorption spectrum. The relative intensities of the two low-binding energy peaks furthermore vary depending on the Mn atomic environment, reflecting the changes in the properties of the Mn 3d band rather than the geometric position of the Mn atoms. For Mn coverages ≤1 monolayer, the highest degree of Mn 3d localization was found for structures in which the Mn atoms are spread uniformly over the surface. The observed changes in the Mn 2p spectra are discussed in terms of varying Mn-Pd interaction, exchange splitting and magnetic ordering