Image states: Binding energies, effective masses, and surface corrugation

We show that image-potential surface states are strongly affected by surface corrugation. In particular, their binding energy and effective mass are strongly coupled. New inverse-photoemission measurements for Ag(100) indicate that neglect of the corrugation contribution to the binding in previous work has caused (i) the confusion of the fundamental and excited image states and (ii) underestimation, by a factor of 3, of the spatial extent of the states observed. © 1985 The American Physical Society.