Quantification of the Helical Morphology of Chiral Gold Nanorods

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.

Automated summary

Chirality in inorganic nanoparticles and nanostructures has attracted increasing scientific interest due to their ability to interact differently with circularly polarized light. Quantifying the degree of chirality in objects of nanoscale is challenging, but the authors introduce a methodology based on helical geometrical properties to quantify the helicity of complex chiral nanomaterials. They demonstrate that analyzing individual particles can provide significant insights into the origin of chiroptical properties.