Core-level spectroscopy of the Pd/W(110) interface: Evidence of long-range Pd-island-W interactions at submonolayer Pd coverages

Abstract

We have measured W 4f(7/2) core-level photoemission spectra from W(110) in the presence of Pd overlayers for coverages up to similar to 1 pseudomorphic monolayer (ML). At coverages close to 0.05 ML a striking change in the W core-level spectrum is observed, which we interpret as indicating a long-range lateral effect of 2D Pd islands upon the W electronic structure in both the first and second W layers. As the coverage increases the long-range effect weakens and finally vanishes near 0.85 ML Above this coverage the W spectra are typical for a W-based bimetallic interface, with the first-layer W atoms exhibiting a small interfacial core-level shift (-95 +/- 5 meV) compared to the bulk atoms. (C) 2009 Elsevier B.V. All rights reserved.