(369a) Pulsed Laser Ablation in near-Critical Carbon Dioxide for Nanoparticle Fabrication

Fabrication of nano-structured materials has been developed by performing pulsed laser ablation of gold and silver plates in sub- and supercritical region of CO₂. The gold and silver nano-structured particles were successfully generated. Laser ablation was performed with an excitation wavelength of 532 nm. On the basis of the experimental result, both surface of ablated gold and silver plates and structure of gold and silver nano-structured particles were significantly affected by the changes in supercritical CO₂density. It was observed that the ablation was more significant at near-critical pressure. 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.