Toroidal nano-traps for cold polar molecules

TL;DR

This paper proposes using toroidal gold nanorings as nanoscale traps for polar molecules, analyzing their optical properties and potential for array configurations, with implications for molecular manipulation.

Contribution

It introduces a novel concept of trapping polar molecules with toroidal metallic nanoparticles and explores their scattering and field distribution properties computationally.

Findings

Nanorings can form nanoscale traps under specific conditions.

Resonant plasmonic response can hinder trap formation.

Array configurations like dimers and trimers extend trapping possibilities.

Abstract

Electronic excitations in metallic nanoparticles in the optical regime that have been of great importance in surface enhanced spectroscopy and emerging applications of molecular plasmonics, due to control and confinement of electromagnetic energy, may also be of potential to control the motion of nanoparticles and molecules. Here, we propose a concept for trapping polarizable particles and molecules using toroidal metallic nanoparticles. Specifically, gold nanorings are investigated for their scattering properties and field distribution to computationally show that the response of these optically resonant particles to incident photons permit the formation of a nanoscale trap when proper aspect ratio, photon wavelength and polarization are considered. However, interestingly the resonant plasmonic response of the nanoring is shown to be detrimental to the trap formation. The results are in good agreement with analytic calculations in the quasi-static limit within the first-order perturbation of the scalar electric potential. The possibility of extending the single nanoring trapping properties to two-dimensional arrays of nanorings is suggested by obtaining the field distribution of nanoring dimers and trimers.