Adlayer core-level shifts of admetal monolayers on transition-metal substrates and their relation to the surface chemical reactivity

Using density-functional theory, we study the electronic and structural properties of a monolayer of Cu on the fcc(100) and (111) surfaces of the late 4d transition metals, as well as a monolayer of Pd on Mo bcc(110). We calculate the ground states of these systems, as well as the difference of the ionization energies of an adlayer core electron and a core electron of the clean surface of the adlayer metal. The theoretical results are compared to available experimental data and discussed in a simple physical picture; it is shown why and how adlayer core-level binding energy shifts can be used to deduce information on the adlayer's chemical reactivity.