Influence of pressure and pulse energy on the expansion dynamics of nanoparticle-enhanced laser produced plasma

Abstract

In the present work, we have studied the influence of pressure and pulse energy on the expansion dynamics of nanoparticle-enhanced laser produced plasma (NELPP) for two different metals, copper and aluminum. The targets were ablated using a Q-switched Nd:YAG laser operating at its primary wavelength of 1064 nm. The plasma imaging was recorded using the fast-gated ICCD camera. Although spectroscopic investigation of signal enhancement of emission line intensities in presence of nanoparticles (NPs), nanoparticle enhanced LIBS (NELIBS), has been performed extensively, expansion dynamics for NELIBS is not yet studied. We have carried out a detailed investigation of the plume propagation of NELPP for different pulse energies and ambient pressures. Temporal evolution of the distance of propagation of the plume front at different laser fluences and pressures shows a good agreement with the existing theoretical models. By comparing different plume propagation parameters, such as diameter, aspect ratio and expansion velocity, we have shown that the NELPP plume shows similar behavior as of LPP and its evolution can be explained with the existing models. Hence NPs, though influence the ablation process, do not alter the overall plume dynamics during the course of plasma evolution as observed for the two metals.