Surface-enhanced Raman scattering at Pt nanoaggregates

After preparing Pt nanoparticles by laser ablation in distilled water, centrifugation was repeatedly applied to obtain nanoparticles with sizes greater than ∼15 nm. Surprisingly, platinum aggregates composed of ∼17 nm Pt nanoparticles on silicon wafer or ITO exhibited fairly strong surface-enhanced Raman scattering such that the enhancement factor for benzenethiol adsorbed thereon, for instance, could reach values as large as 200 with 514.5 nm excitation.