Superchiral hotspots in real chiral plasmonic structures

TL;DR

This study demonstrates that real chiral plasmonic structures create superchiral hotspots around surface irregularities, which could enhance the sensitivity of chiral molecule detection beyond idealized models.

Contribution

It reveals that structural heterogeneities in real metal structures generate superchiral hotspots with greater asymmetry than perfect models, impacting sensing applications.

Findings

Superchiral hotspots are formed around protrusions and indentations.

Surface morphology influences the effectiveness of chiral sensing.

Hotspots exhibit greater chiral asymmetry than ideal structures.

Abstract

Light scattering from chiral plasmonic structures can create near fields with an asymmetry greater than the equivalent circularly polarised light, a property sometimes referred to as superchirality. These near fields with enhanced chiral asymmetries can be exploited for ultrasensitive detection of chiral (bio)molecules. In this combined experimental and numerical modelling study, we demonstrate that superchiral hot-spots are created around structural heterogeneities, such has protrusions and indentations, possessed by all real metal structures. These superchiral hot-spots, have chiral asymmetries greater than what would be expected from an idealised perfect structure. Our work indicates that surface morphology could play a role in determining the efficacy of a chiral structure for sensing.