A semiclassical two-temperature model for ultrafast laser heating

A semiclassical two-step heating model is proposed to investigate thermal transport in metals caused by ultrashort laser heating. Based on the Boltzmann transport equation, three equations of the conservation of number density, momentum and energy are derived for the electron subsystem. The thermal transport equation used for the phonon subsystem remains the same as that used in the phenomenological two-temperature (2T) model, including the energy exchange with hot electrons and the ultrafast thermal relaxation effect in general. The main difference between the semiclassical and the phenomenological 2T models is that the former includes the effects of electron drifting, which could result in significantly different electron and lattice temperature response from the latter for higher-intensity and shorter-pulse laser heating.