Characterization of Copper nanoparticles obtained by laser ablation in liquids

We prepared copper nanoparticles by ns laser ablation in pure water and in aqueous solutions of 1,10-phenanthroline at 1064 nm and 532 nm wavelengths. Although not fully impairing progressive oxidation, ligand molecules prevent the colloids to collapse. UV–vis absorption spectroscopy showed that particle production is more efficient at 1064 nm, while transmission electron microscopy gave evidence that 532-nm pulses cause photofragmentation of the structures, resulting in reduced particle size. Furthermore, from Raman and fluorescence tests we found that colloids obtained at 1064 nm show better Surface Enhanced Raman activity, while colloids obtained at 532 nm exhibit a more intense fluorescence emission.