Fabrication of Metal Nanoparticles by Pulsed Laser Ablation in Supercritical CO2

Fabrication of nano-structured materials has been developed by performing pulsed laser ablation of copper, gold, and silver plates in supercritical CO2. The metal nano-structured particles were successfully generated with allowing the selective generation of clusters. Laser ablation was performed with an excitation wavelength of 532 nm. On the basis of the experimental result, both surface of ablated metal plates and structure of nanoparticles were significantly affected by the changes in supercritical CO2 density. The deepest crater was created near the critical pressure of CO2. As increasing irradiation time, plume deposited in the surrounding crater created by the ablation was clearly observed. In FE-SEM image of the generated gold nano-structured particles on silicon wafer, a network structure of smaller gold particles was fabricated. The network structure consists of gold nanoclusters with an average diameter of approximately 30 nm in ensembles of 300-800 nm length. The difference morphology of particles fabricated from silver plate was observed. Based on the results, this new method can also be used to obtain advanced nano-structured materials. Keyword: pulsed laser ablation, supercritical CO2, gold nanoparticles, silver nanoparticles