Surface-Enhanced Plasmon Splitting in a Liquid-Crystal-Coated Gold Nanoparticle

TL;DR

This paper demonstrates that liquid crystal coatings on gold nanoparticles can significantly enhance surface plasmon splitting, with specific director configurations influencing the extent of splitting, confirmed by calculations and experiments.

Contribution

It reveals that nanoparticle surface deformation by liquid crystals can enhance plasmon splitting, a novel insight supported by discrete dipole approximation calculations and experimental validation.

Findings

Boojum pair configuration yields the largest plasmon splitting.

Surface deformation influences director orientation significantly.

Experimental results agree with theoretical predictions.

Abstract

We show that, when a gold nanoparticle is coated by a thin layer of nematic liquid crystal, the deformation produced by the nanoparticle surface can enhance the splitting of the nanoparticle surface plasmon. We consider three plausible liquid crystal director configurations in zero electric field: boojum pair (north-south pole configuration), baseball (tetrahedral), and homogeneous. From a calculation using the Discrete Dipole Approximation, we find that the surface plasmon splitting is largest for the boojum pair, intermediate for the homogeneous, and smallest for the baseball configuration. The boojum pair results are in good agreement with experiment. We conclude that the nanoparticle surface has a strong effect on the director orientation, but, surprisingly, that this deformation can actually enhance the surface plasmon splitting.