Multi-scale visualization of colloidal particle lens array (CPLA) mediated plasma dynamics for dielectric nanoparticle enhanced fs-LIBS

A multiscale visualization of silica colloidal particle lens array (CPLA) assisted laser ablation of copper is investigated. The distributed holes on a crater of CPLA-deposited Cu (CPLA-Cu) show a near-field effect by the silica nanoparticles (NPs), and the plasma emission signal of CPLA-Cu is 3–5 times as strong as that of Cu. Time-resolved plasma expansion, shockwave propagation, plasma plume emission, and nanoparticle distribution are observed and analyzed for ablations on both Cu and CPLA-Cu substrates. The initial expansion of plasma generated on CPLA-Cu is faster than that of pristine Cu. The shockwave of CPLA-Cu is rounder and its plasma plume is wider than those of Cu. The nanoparticle distribution shows a strong lateral collision during plume ejection for CPLA-Cu. Plasma characterization shows the increased plasma temperature is the key reason for femtosecond laser-induced breakdown spectroscopy (fs-LIBS) signal enhancement. This work demonstrates the signal enhancement effect of dielectric NPs o...