Inverse photoemission is used to examine the adsorbate-induced unoccupied band structure of the c(2×2)CO/Cu(001) adsorption system. As in an earlier study we observe two adsorbate-induced peaks above the Fermi level. By comparing with a simple tight-binding model we associate one unoccupied adsorbate band with the molecular 2π level and another band with a substrate surface band interacting with the molecular 5σ level.

• Received 22 April 1992

DOI:https://doi.org/10.1103/PhysRevB.45.13827