Inverse photoemission spectroscopy of the unoccupied electronic structure of Na/Cu(110)

The unoccupied electronic states of Na thin films on a Cu(110) substrate have been measured by inverse photoemission spectroscopy (IPES). The IPES spectrum provides the intensity of the unoccupied states, which decreases with increasing Na coverage at off-normal incidence of the electron beam. The IPES spectra at 17 and 19 eV incident electron energies show a shift towards the Fermi level with increasing Na coverage for the peak at ∼7.8 eV.