A multilayer model of a single coated nanoparticle has been refi nedthrough fi nite elements method based simulations and resulted in a successful matching ofthe experimental UV− visible spectra of ligand-coated silver nanoparticles. Thecomputational matching of the surface plasmon resonance (SPR) band reveals both aligand-type dependence of the eff ective plasma frequency and a size dependence of theSPR damping eff ect within the modeled nanoparticle. The observed diff erences ofeff ective plasma frequency between thiol and amine-coated nanoparticles are consistentwith the already known stronger bonding of thiols on silver compared to amines. Thesignifi cant increase of the damping eff ect at the surface of the nanoparticle whenincreasing their size suggests an inverse relation between the ligand packing density and the nanoparticle size, which is supported by the expected infl uence of the surfacecurvature radius on the ligand packing.
Source : Computational Matching of Surface Plasmon Resonance: Interactions Between Silver Nanoparticles and Ligands. J. Romann, J. Wei, M.P Pileni J.Phys.Chem.C, 2015, 119, 11094−11099.