Femtosecond time-resolved reflectivity of hydrodynamically expanding metal surfaces

Abstract

We present femtosecond time-resolved p- and s-polarized reflectivity measurements of silver, aluminum, and tungsten surfaces that are hydrodynamically expanding in response to pulsed laser excitation. A numerical model of the experimental results shows that (1) electron heating and surface expansion influence the reflectivity on distinguishable time scales and (2) covalency, described by non-Drude dielectric constants, is necessary to explain the time-resolved reflectivity of the tungsten target.