We report the direct observation of the thermalization of electrons in gold following 180 fs optical pulse excitation. The evolution of the electron energy distribution from the nascent (as photoexcited) to a hot Fermi-Dirac distribution was measured by time-resolved photoemission spectroscopy. Depending on the excitation density, thermalization times as long as ≊1 ps were observed. A model incorporating both electron-electron and electron-phonon scattering, and using Fermi-liquid theory to properly account for screening is found to reproduce the main features of the experiment.

• Received 2 June 1992

DOI:https://doi.org/10.1103/PhysRevB.46.13592