Surface enhanced circular dichroism spectroscopy mediated by non-chiral nanoantennas

TL;DR

This paper presents a theoretical framework showing how non-chiral nanoantennas can enhance circular dichroism spectroscopy by supporting electric and magnetic dipoles, enabling improved chiral molecule detection.

Contribution

It provides the first theoretical conditions necessary and sufficient for enhancing circular dichroism using non-chiral nanoantennas, advancing chiral spectroscopy techniques.

Findings

Isotropic nanoantennas can locally enhance chiral polarizability

Simultaneous electric and magnetic dipoles are needed for net enhancement

Framework guides design of nanoantennas for chiral spectroscopy

Abstract

We theoretically investigate light matter interactions for chiral molecules in the presence of non-chiral nanoantennas. Isotropic nanostructures supporting optical-frequency electric or magnetic dipoles are sufficient to locally enhance the excitation of a molecule's chiral polarizability and thus its circular dichroism spectrum. However, simultaneous electric and magnetic dipoles are necessary to achieve a net, spatially-averaged enhancement. Our contribution provides a theoretical framework to understand chiral light-matter interactions at the nanoscale and sets the necessary and sufficient conditions to enhance circular dichroism spectroscopy in the presence of nanoantennas. The results may lead to new, field-enhanced, chiral spectroscopic techniques.