Electron Collision Rate in Ultrashort Laser – Metal Interaction Inferred from Reflectivity Measurements

Abstract

We study optical laser coupling of four metals (aluminum, copper, nickel and tungsten) upon single ultrashort 30-fs laser irradiation. Using dedicated experimental methodology, we carefully monitor the evolution of the material reflectivity integrated over the femtosecond pulse duration. We further apply the Drude-Lorentz formalism to infer the evolution of the effective electron collision rate eff as a function of applied fluence. The knowledge of this parameter is of paramount importance in any lasermatter interaction situation because of its immediate impact on laser energy coupling in material and on its subsequent macroscopic transformation.