Electronic and geometric structure of Cs on graphite (0001)

An investigation of the geometric and electronic structure of submonolayer coverages of Cs adsorbed on the graphite (0001) surface has been carried out. At very low coverages a dispersed phase is observed, similar to that previously reported for the case of K adsorption on graphite, together with a surface plasmon frequency shift induced in the substrate by charge redistribution. However, rigid-band calculations indicate that the nominal charge transfer to the substrate from the dispersed Cs adatoms is greater than that from K adatoms. At higher coverages, some qualitative differences are seen when the electronic excitation spectra for Cs are compared to those for K overlayers. These differences may be attributed to the geometric structure of the adsorbate layer.