Evolution of the Electronic Structure During the Epitaxial Growth of Au on Pt(100)

We report an angle-resolved photoemission study of the electronic structure of Au layers grown epitaxially on Pt(100) in the coverage range 1–10monolayers (ML). Our results include an analysis of the electronic band structure and the Fermi surface, combined with structural information from low-energy electron diffraction. The Au films grow epitaxially with a (1×1) pattern up to 4–5ML. We monitor the electronic band structure near the surface X¯-point vs. Au coverage. In the 1–3ML range we observe interface electronic states related to the formation of a Au–Pt alloy in this coverage range. Starting at 2–3ML coverage, we identify quantum well states from the incipient Au sp band, which converge into a bulk like Au sp band near 6ML. After 5–6ML, a (1×7) pattern is observed, due to the formation of a surface reconstruction in the epitaxial Au film with a topmost hexagonal layer, as in the reconstruction of bulk Au(100). We identify specific electronic states of quasi-one-dimensional character coming from the corrugated hexagonal layer. We obtain a complete picture and understanding of the electronic structure of Au/Pt(100), including sp Au band formation, hybridization and electronic confinement, and with implications in the understanding of the distinct electronic behavior of Au layers and particles in the nm size range.