Trapping of gold nanoparticles within arrays of topological defects: evolution of the LSPR anisotropy

Abstract

We demonstrate how the localized surface plasmon resonance (LSPR) of gold nanoparticles is affected by their trapping within topological defect cores. Using aligned arrays of smectic edge dislocations, we evidence a reversal of the LSPR anisotropy, when the nanoparticle concentration increases. We combine UV-visible spectroscopy with simulations to show that this reversal is related to a transformation of the nanoparticle organization. When the concentration increases, the organization varies from nanoparticle chains parallel to the dislocations to anisotropic nanoparticle ribbons, larger in the direction perpendicular to the dislocations, moreover denser perpendicular to the dislocation than parallel to the dislocations. This transformation may be associated with the localized presence of dense arrays of aligned dislocations, inducing a compression between the NPs, but only in the direction perpendicular to the dislocations.