High-resolution photoemission study of long-lived d-holes in Ag

We present a high-resolution study of photoemission line widths observed at Ag(1 1 0). A careful data analysis yields k-resolved hole lifetimes τh of d-holes at the X-point of the bulk band structure. At the upper d-band edge we derive τh⩾22 fs, i.e. more than one order of magnitude larger than predicted for a free-electron gas. In agreement with recent ab initio calculations for d-hole dynamics in Ag we interpret this lifetime enhancement by a small scattering cross-section of d-holes with sp-states below the Fermi level EF. With increasing distance to EF the d-hole lifetimes get rapidly shorter because of the increasing density of d-states and corresponding contributions of intra-d-band scattering processes.