Nanoparticle Enhanced Laser Induced Breakdown Spectroscopy (NELIBS): effect of nanoparticles deposited on sample surface on laser ablation and plasma emission.

In this paper the use of metallic nanoparticles (NPs) for improving Laser Induced Breakdown Spectroscopy (LIBS) is discussed. In the case of conductors an emission signal enhancement up to 1-2 orders of magnitude was easily obtained depositing NPs on the sample surface by drying a micro-drop of colloidal solution. The basic mechanisms of Nanoparticles Enhanced LIBS (NELIBS) were studied and the main causes of the huge enhancement were found to be related to the effect of NPs on the laser ablation process, in terms of a faster and more efficient production of seed electrons with respect to conventional LIBS. The characteristics of NELIBS-produced plasma were investigated by fast emission spectroscopy and spectral resolved image, and in spite of similar plasma parameters , the NELIBS plasma was found to have larger emission volume and longer persistence than the LIBS one. On the other hand a methodology for determination of NPs concentration and size was pointed out when the NPs are deposited on insulators, proving the feasibility of LIBS as a fast detection tool for a preliminary characterization of NPs.