Magneto-Plasmonic Colloidal Nanoparticles Obtained by Laser Ablation of Nickel and Silver Targets in Water

Stable magneto-plasmonic nanoparticles in colloidal suspensions are fabricated by two-step nanosecond-pulsed laser ablation of nickel and silver targets in pure water and characterized by UV-visible absorption, Raman, X-ray photoelectron spectroscopic, and magnetic measurements, along with high-resolution electron microscopy analysis. These systems are constituted by a low-crystallinity matrix of ferromagnetic nickel hydroxide, where nickel oxide nanocrystals are embedded, with silver nanoparticles intimately linked to them. The surface enhanced Raman scattering activity is assessed by adsorption of adenine as probe ligand. Spectroscopic investigation and density functional theory calculations revealed that adenine is linked to nickel oxide, while nanosilver essentially plays the role of ensuring the Raman enhancement for the adsorbed organic ligand. Both magnetic and plasmonic properties allow using these nanostructured bimetallic platforms as catalysts in chemical reactions or nanosensors in biomedicine as well as in environmental research.