Experimental determination of the unoccupied bands of W(110)

Inverse photoemission from W(110) has been used to determine the dispersion of the unoccupied energy bands along the tungsten {Γ}{Σ}N line. The critical points are determined to be Γ₁₂ at 2.6 eV, N₁ at 2.2 eV, and the lower limit of N₄ at 3.2 eV. The upper bound of the lifetime broadening is estimated as 0.3-0.4 eV at 2-3 eV above EF. The image state is observed at 4.5 eV above EF, or 0.7 eV in binding energy, relative to the vacuum level.