Determination of the hole lifetime from photoemission : Ti 3d states in TiTe2

: The electron hole spectral width Gamma(h) of Ti 3d states in layered TiTe2 and the inverse lifetime V(i) of the photoelectron final states are determined from experiment within the one-step theory of photoemission. The condition for the possibility of separating the effects of Gamma(h) and V(i) is a strongly non-free-electron character of the final states. The resulting drastic changes of the line shape with photon energy are experimentally observed and explained by an ab initio theory. A nonmonotonic dependence of V(i) on the final-state energy is observed; it is shown to reveal the real space structure of the complex electron self-energy.