Abstract

When a metal is subjected to a transient event (femtosecond lasers, a fast electrical current, or energetic charged particles), energy is initially coupled to the electron gas. Hot electrons then transfer their energy to the lattice by inelastic collisions or exit the surface of the metal by a single-photon or a multi-photon photoemission (Fig. 1). For conditions discussed here, energy loss by photoemission is significantly smaller than that due to inelastic collisions so that it can be neglected. The possibility of creating nonequilibrium heating conditions where hot electrons can be generated in metals during the passage of ionizing radiation was postulated many years ago.¹ The advent of ultrafast lasers has made accessible the generation and the study of such a nonequilibrium state.

© 1989 Optical Society of America