Abstract

The possibility of creating and probing a transient nonequilibrium electron population in metals with ultrashort laser pulses has been demonstrated by different groups.^1,2 Because of the large electron densities, electron-electron interactions were assumed to be sufficiently fast to instantaneously thermalize the electron gas, although some deviations from Fermi-distribution behavior were observed dose to the Fermi surface.² Recently, by using a photoemission technique, thermalization times as long as 600 fs were measured in gold films for large changes of the electron temperature (of the order of 400 K).³

© 1993 Optical Society of America