Empty electronic states of silver as measured by inverse photoemission

We have performed inverse photoemission (bremsstrahlung isochromat spectroscopy) at $h_{\nu }=9.7\mathrm{}$ eV on polycrystalline silver. Our spectrum can be related to the calculated density of unoccupied states up to 7 eV above the Fermi level $E_F$. Pronounced features in the isochromat spectrum are associated with critical points in the band structure of silver. We find $X_6^{-}$ at $E_F+(2.1\mathrm{}\pm 0.1)$ eV and $L_4^{+}$ at $E_F+(3.77\mathrm{}\pm 0.09)$ eV. The results are compared with band-structure calculations as well as other experimental findings.