Coulomb explosion in ultrashort pulsed laser ablation of Al2O3

Coulomb explosion (CE) is identified as the mechanism of ion ejection under low fluence ultrashort pulse laser ablation of crystalline Al2O3 The ion moments are equal during gentle ablation. This is explained by impulsive CE from the surface region lasting similar to1 ps. The onset of strong ablation leads to a decrease in the measured ion velocitics. The kinetic energies rather than the momenta of the ions become equal. This regime is associated with strong plasma light emission and crater formation.