Plume composition control in double pulse ultrafast laser ablation of metals

Ultrafast laser ablation of a metallic target induced by a pair of identical laser pulses temporally delayed from ≈1 to 2000 ps was studied by optical emission spectroscopy, imaging, and ion probe. Our experimental results demonstrate that plume excitation/ionization enhancement or nanoparticles reduction is achieved by properly delaying the two pulses. This possibility of controlling plume composition via an efficient coupling of the energy of the second pulse to the various ablation components produced by the first pulse is of particular interest in the process of material deposition and film growth.