Plasma charging effect on the nanoparticles releasing from the cavitation bubble to the solution during nanosecond Pulsed Laser Ablation in Liquid

The laser induced plasma during the nanosecond Pulsed Laser Ablation in Liquid (PLAL) plays a crucial role in the nanoparticles (NPs) formation and charging. It was demonstrated that during the plasma phase evolution, once the NPs are formed, they are charged with the excess of plasma electrons. Immediately after the plasma phase extinguishes, the NPs will be released in the induced vapor bubble, generated by the fast energy exchanges between the plasma and the liquid. The excess of charge in the NPs preserves them from the agglomeration during the bubble evolution and can induces an electrostatic pressure able to eject the particles outside the cavitation bubble. In this work, the plasma charging effect on the particle releasing in solution, during the bubble evolution, has been investigated. Temporal evolution of laser induced bubble on silver target immersed in water has been measured with the shadowgraph technique. Then, starting from the experimental bubble radius evolution, the releasing of the NPs from the cavitation bubble to the liquid has been modeled by comparing the electrostatic pressure of the charged NPs cloud and the pressure of the cavitation bubble. The following discussion proposes a new insight of the mechanism of NPs releasing in solution.