The electron-phonon self-energy of metallic systems determined by angular resolved high-resolution photoemission

By use of modern high-resolution photoemission spectrometers, one is able to determine experimentally both the real and the imaginary part of the electron-phonon self-energy Sigma(el-ph) of metallic systems. Here, we present angular resolved photoemission data (ARUPS) on the Shockley-type surface state on Cu(1 1 1), a model system for the investigation of many-body effects in solids. By analyzing the line width and the peak position of the surface state, one can extract its self-energy which can be compared to a simple theoretical description using the Debye model. We discuss to what extent these results can be transferred to the electronic structure of a three-dimensional solid with strong electron-phonon effects, e.g. Pb(1 1 0), which is a classical example for a superconductor in the strong-coupling regime. (C) 2004 Elsevier B.V. All rights reserved.