Abstract

Intense femtosecond excitation of metal targets has attracted fundamental interest in the properties of solid-density plasmas^1–3 as well as practical interest in the generation of ultrafast soft x-ray pulses.⁴ In several recent studies,^1,2 the ultrafast response of reflectivity from metal targets was observed with a single intense pulse serving both as target excitation and as optical probe. Consequently, it was difficult to distinguish the competing processes of electron heating and hydrodynamic surface expansion, which influence the optical reflectivity to different degrees and at different times.

© 1992 Optical Society of America