Experimental determination of the unoccupied bands of W(110)

Abstract

Inverse photoemission from W(110) has been used to determine the dispersion of the unoccupied energy bands along the tungsten ΓΣN line. The critical points are determined to be ${\mathrm{\Gamma }}_{12}$ at 2.6 eV, ${\mathit{N}}_1$ at 2.2 eV, and the lower limit of ${\mathit{N}}_4$ at 3.2 eV. The upper bound of the lifetime broadening is estimated as 0.3-0.4 eV at 2-3 eV above ${\mathit{E}}_{\mathit{F}}$. The image state is observed at 4.5 eV above ${\mathit{E}}_{\mathit{F}}$, or 0.7 eV in binding energy, relative to the vacuum level.