Elastic displacement of surface due to laser picosecond pulse heating of gold

Laser picosecond pulse heating initiates nonequilibrium energy transport in the surface vicinity of the metallic substrates. In this case, electron temperature rises rapidly while lattice site temperature is slow during the heating period. Although the rise of lattice site temperature is low, the temperature gradient is high. This results in elastic displacement of the surface. To model the heating process thermomechanical coupling needs to be introduced in the analysis. In the present study, picosecond pulse heating of gold surface is considered. Three-dimensional analysis of electron kinetic theory is introduced when formulating the electron and the lattice site temperatures. The analysis is extended to include the thermomechanical coupling due to mechanical response of the substrate material. The lattice site temperatures obtained from the electron kinetic theory are compared with the predictions of the two-equation model. It is found that both models predict almost identical temperature profiles in the surface vicinity of the substrate material. In addition, the surface displacement on the order of 10⁻¹¹ m is predicted.