Effect of hydrocarbon molecular decomposition on palladium-assisted laser-induced plasma ablation.

The Q-switched Nd:YAG laser is focused on a palladium target in the control chamber filled with various hydrocarbon atmospheres (C1-C4) to investigate their effect on the palladium ablated mass, gas reaction products, and corresponding plasma parameters (such as electron density N and plasma temperature T) during molecular decomposition. The plasma parameters arise mainly from the Pd nanocatalytic activity during the laser-induced plasma process. We compare synthetic air atmosphere to hydrocarbon media to understand how the latter generates excess heat via oxygen-free exothermic (recombination) reactions. Subsequently, this gives rise to more energetic plasma and higher temperature, regarding the large amount of nanoparticles released into the plasma. The dynamics of the decomposition/recombination events accompany the nanocatalyst activity, leading to soot deposition all over the chamber.