Image-potential surface states on Ag(100): A reinvestigation

Employing inverse photoemission we have remeasured the energy dispersion E(k) of the lowest-lying image state on Ag(100) with improved energy resolution (electrons and photons, ΔE=0.35 eV) and k-resolution (Δk<0.1 Å-1). In a least-square fit with the binding energy EB at k=0 and the effective mass m* as parameters we obtain EB=Evac -0.67 eV and m*=1.5 m in agreement with our earlier findings but differing from the two-photon photoemission values (∼0.53 eV and 1.15 m). © 1987 Springer-Verlag.