Natural linewidth analysis of d-band photoemission from Ag(110)

We report a high-resolution angle-resolved study of photoemission linewidths observed for Ag(110). A careful data analysis yields k -resolved upper limits for the inverse inelastic lifetimes of d -holes at the X-point of the bulk band structure. At the upper d -band edge the hole-lifetime is τ h ≥ 22 fs, i.e. more than one order of magnitude larger than predicted for a free-electron gas. Following calculations for d -hole dynamics in Cu (I. Campillo et al., Phys. Rev. Lett., in press) we interpret the lifetime enhancement by a small scattering cross-section of d - and sp -states below the Fermi level. With increasing distance to E F the d -hole lifetimes get shorter because of the rapidly increasing density of d -states and contributions of intra- d -band scattering processes, but remain clearly above free-electron-model predictions.