Quantification of the helical morphology of chiral Au nanorods

TL;DR

This paper presents a new method to quantify the helical morphology of chiral gold nanorods using electron tomography, providing insights into their optical activity at the single-particle level.

Contribution

A novel quantitative approach to measure nanorod helicity based on geometrical analysis, advancing understanding of chiroptical properties.

Findings

Method enables quantification of nanorod helicity

Single-particle analysis reveals origins of chiroptical activity

Provides a link between morphology and optical properties

Abstract

Chirality in inorganic nanoparticles and nanostructures has gained increasing scientific interest, because of the possibility to tune their ability to interact differently with left- and right-handed circularly polarized light. In some cases, the optical activity is hypothesized to originate from a chiral morphology of the nanomaterial. However, quantifying the degree of chirality in objects with sizes of tens of nanometers is far from straightforward. Electron tomography offers the possibility to faithfully retrieve the three-dimensional morphology of nanomaterials, but only a qualitative interpretation of the morphology of chiral nanoparticles has been possible so far. We introduce herein a methodology that enables us to quantify the helicity of complex chiral nanomaterials, based on the geometrical properties of a helix. We demonstrate that an analysis at the single particle level can provide significant insights into the origin of chiroptical properties.