Determining the electron-phonon mass enhancement parameter λ on metal surfaces

We discuss various approaches for determining the strength of the electron-phonon coupling on metal surfaces by angle-resolved photoemission. The first is to extract the electron-phonon mass enhancement parameter. directly from the re-normalization of the band dispersion very close to the Fermi level. The second is to use the temperature-dependence of photoemission spectra such as energy distribution curves (EDCs) or momentum distribution curves (MDCs). We illustrate the advantages and disadvantages of both methods with the help of simulated spectral functions. Using experimental data, we find lambda = 0.40(5) for Bi(111) by analyzing temperature-dependent MDCs.