Time-dependent fundamental processes following ns pulsed laser absorption by metallic targets

An experimental study of the evolution of nanosecond pulsed lasers absorbed by Ni metal is presented. The ions ejected near fluence threshold fit single Maxwell–Boltzmann distributions (MBDs) whereas the ion distributions at higher fluences have side-bands whose maxima match accurately those of the ionization and recombination precursors. It is demonstrated that ions are trapped for ≈1 μs and further ejected in a few picoseconds whereas electrons have shorter dead time (≈10 ns) and continue evaporating for as long as ≈1 μs. Radiation is partially trapped during the creation of the electric field that ejects ions. The evolution also applies to other metals.