We have measured W 4f7/2 core-level photoemission spectra from W(1 1 0) in the presence of Pd overlayers for coverages up 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.
"Core-Level Spectroscopy of the Pd/W(110) Interface: Evidence of Long-Range Pd-Island—W Interactions at Submonolayer Coverages," D. M. Riffe, N. D. Shinn, B. Kim, K. J. Kim, and T.-H. Kang, Surface Science 603, 1070 (2009) (doi:10.1016/j.susc.2009.02.026).