Layer-by-Layer Band Structure of Physisorbed Xe on Al(111)

The dispersion of Xe-$5p$ valence-band states is studied layerwise for multilayers of Xe physisorbed on Al(111) by means of the layer-dependent shifts of photoelectron energies due to screening of the photohole. While the bilayer band structure is essentially the sum of two singlelayer band dispersions, Xe bulk bands begin to form with the third layer. Nondispersive peaks are also observed in the photoemission spectra, and are assigned to indirect transitions from critical points in the Xe surface Brillouin zone.