Empty surface states, image states, and band edge on Au(111)

Inverse-photoemission observations on Au(111) reveal the n=1 image stage, the L₁ (L₆⁺) band edge, and the continuation above the Fermi level EF of the well-established Shockley surface state. The image-state binding energy (0.60±{}0.05 eV) is lower than that obtained on Cu(111) or Ag(111), or that expected on the basis of elementary multiple-reflection theory (0.85 eV). The L₁ (L₆⁺) level is found to occur 3.6±{}0.1 eV above EF. .AE