Formation of silver nanoparticles oligomers obtained via laser ablation in a liquid by sequential centrifugation and ultrasonication: tunable long-wavelength shift of plasmon resonance for biomedical applications

A relatively simple physical method has been proposed for fabrication of stable oligomers of silver nanoparticles, preliminarily obtained by pulsed laser ablation of a metal target in a liquid. Oligomers of silver nanoparticles are formed in an aqueous solution after prolonged centrifugation at 18000 g and subsequent ultrasonication of the initial colloidal solution of spherical nanoparticles obtained by laser ablation. The plasmon resonance in oligomers is shifted relative to the plasmon resonance in spherical nanoparticles to the long wavelength region by 140 nm.