Using high-resolution temperature-dependent (20–400 K) valence-band photoemission spectroscopy, we study the nature of electron-phonon coupling in polycrystalline gold. The valence band shows systematic broadening for increasing temperatures which is well-reproduced by a Gaussian broadening of the 20 K spectrum. It depends linearly on temperature and is found to be excessive (∼9 ${\mathrm{k}}_{\mathrm{B}}$ T). The results suggest the existence of anharmonic lattice vibrations and a quadratic electron-phonon coupling, similar to the case of aluminum 2p core levels.

DOI:https://doi.org/10.1103/PhysRevB.55.5574