Kinetics of propagation of the lattice excitation in a swift heavy ion track

In this research we verify the applicability of the temperature and heat diffusion conceptions for the description of subpicosecond lattice excitations in nanometric tracks of swift heavy ions (SHI) decelerated in solids in the electronic stopping regime. The method is based on the molecular dynamics (MD) analysis of temporal evolutions of the local kinetic and configurational temperatures of a lattice. We used solid argon as the model system. MD simulations demonstrated that in a SHI track (a) thermalization of lattice excitations takes time of several picoseconds, and (b) application of the parabolic heat diffusion equations for the description of spatial and temporal propagation of lattice excitations is questionable at least up to 10 ps after the ion passage.