Hot electron lifetimes in metals probed by time-resolved two-photon photoemission

This review reports on experimental and theoretical results on the inelastic decay of optically excited volume electrons in different types of metals, including simple metals (Al), noble metals (Au, Ag, Cu), transition metals (Ta, Mo, Rh, Co, Fe, Ni) and rare earth metals (Gd, Tb, Yb, La). The comparison of the different materials and material classes provides particular insight into the relevance of the localization and delocalization of electronic states for inelastic carrier scattering processes. The discussion of the data illustrates furthermore the capabilities and limitations of the time-resolved two-photon photoemission technique as well as current theoretical approaches in analyzing and determining inelastic lifetimes of excited electrons.