Abstract
We have determined the unoccupied part of the electronic structure of sodium on Cu(111), employing k-resolved inverse photoemission in the isochromat mode. For Na coverages above 0.15 monolayer, an image-potential surface state is observed 2.3 eV above . For the completed p(2×2) Na phase at 0.25-monolayer coverage, a pronounced Na –derived feature occurs 0.4 eV above , which exhibits a nearly-free-electron-like energy dispersion. For wave vectors ≥0.6 A, the unoccupied part of the Na 3s band appears close to the Fermi level. We compare our results with recent band-structure calculations for free and adsorbed Na monolayers.
- Received 11 February 1991
DOI:https://doi.org/10.1103/PhysRevB.44.1198
©1991 American Physical Society