Relaxation of surface tracks on polycarbonate thin films induced by MeV heavy-ion impacts

In the present work, the relaxation behavior of nanometer-sized deformations produced by single ion impacts on the surface of monodisperse (M_w = 60,000 u) polycarbonate thin films was investigated at temperatures close to and below the glass transition. The relaxation functions for the length, height and width of the deformations were well described by a stretched exponential law, with characteristic relaxation times τ strongly dependent on temperature. For T > 100 °C, the temperature dependence of τ obeys a Vogel-Fulcher law, but for lower temperatures it becomes less steep and tends to an Arrhenius-type behavior.