The effect of aging on optical properties of Au/Pd core-shell nanoparticles by pulsed laser ablation

Optically active surface plasmon resonance modes in noble metals nanoparticles likes Au has figured out application potentials for them. Since various parameters such as particles shape, size and also dielectric constant of their surrounding affect the optical properties, investigations on them are of scientific importance. In this work, Au/Pd core-
shell nanoparticles were synthesized by laser (Nd:YAG pulsed laser, λ=1064 nm) ablation of gold target in PdCl2 solutions. X-ray diffraction (XRD) was used for crystals structure determination. X-ray photoelectron spectroscopy (XPS) determined the surface chemical composition of nanoparticles. Nanoparticles morphologies were observed on TEM. XRD showed the presence of metallic Au, PdCl2 and PdO phases. The effect of aging on nanoparticles was studied by time variations of surface plasmon resonance peaks. Finally, a physical description was given for the observed results.