Experimental study of ultrafast laser-induced phenomena in gold

Intense ultrashort laser pulses can drive the electrons and the lattice in a solid material far out of equilibrium creating a highly excited matter with extraordinary properties. Here, we report on an experimental approach to study the relaxation of electrons in a bulk gold using time-resolved pump-probe reflectivity measurements with phase-sensitive signal detection in a wide range of absorbed energy densities ranging more than two orders of magnitude. As a result, the process of electron relaxation in gold can be seamlessly studied with femtosecond time resolution in a wide range of initial electron temperatures ranging from several tens to several thousands of kelvins by implying appropriate models of transient thermal, mechanical and optical properties. As far as we know, the experimental validation of the theories existing at present time on behavior of such crucial values as electron-phonon coupling parameter, electron thermal conductivity and electron heat capacity is almost lacking in gold driven far out of equilibrium with elevated electrons temperatures ranging from 1 to 20 kK.