Non-spherical aluminum nanoparticles fabricated using picosecond laser ablation

We report the picosecond laser ablation of aluminum targets immersed in a polar organic liquid (chloroform, CHCl 3 ) with ∼2 ps laser pulses at an input energy of ∼350 µJ. The synthesized aluminum nanoparticles exhibited a surface plasmon resonance peak at ∼340 nm. Scanning electron microscopy images of Al nanoparticles demonstrated the spherical morphology with an average size of (27 ± 3.6) nm. The formation of smaller spherical Al nanoparticles and the diminished growth could be from the formation of electric double layers on the Al nanoparticles. In addition to spherical aluminum nanoparticles, triangular/pentagonal/hexagonal nanoparticles were also observed in the colloidal solution. Field emission scanning electron microscopy images of ablated Al targets demonstrated laser induced periodic surface structures (LIPSSs), which were the high spatial frequency LIPSSs (HSF-LIPSSs) since their grating period was ∼280 nm. Additionally, coarse structures with a period of ∼700 nm were observed.