ELECTRON THERMALIZATION IN GOLD

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 almost-equal-to 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.