Angle-resolved photoemission study of the Ag band structure along the ΓΛL line

Angle-resolved photoemission experiments have been carried out on Ag(111) in the photon energy range from 13 to 65 eV with both s- and sp-polarised synchrotron radiation. The valence band structure of Ag has been determined along the high-symmetry Lambda line by normal emission measurements. For photon energies smaller than 24 eV, the photoemission peaks could be interpreted as results of direct transitions between initial and final energy bands in the relativistic band structure calculated by Christensen (1972), and by Eckardt et al. (1984). For photon energies larger than 24 eV, the final band was obtained by fitting a free-electron-like final band (m*_e=1.10, V ₀=-5.0 eV) to experimentally verified calculated symmetry points. The experimental valence bands deviate by about -0.3 eV from theory. Measured critical-point energies (in eV, band indices in parentheses) are: E( Gamma ₈⁺(2,3))=-6.15+or-0.10, E( Gamma ₇ ⁺(4))=-5.70+or-0.10, E( Gamma ₈⁺(5,6))=-4. 95+or-0.10, E(L₆⁺(1))=-7.10+or-0.10, E(L _4,5⁺(2))=-6.25+or-0.10, E(L₆ ⁺(3))=-5.80+or-0.10, E(L₆⁺(4))=-4.55+or-0.10 and E(L_4,5⁺(5))=-4.30+or-0.10. A surface resonance was detected 4.2 eV below the Fermi level at the centre of the surface Brillouin zone Gamma , which has an origin similar to that of the surface resonances that have been observed on Cu(001) and Ag (001). A possible surface state is also reported at about 7.4 eV below the Fermi level at the Gamma point. The nature of this impurity-sensitive structure is not understood.