Abstract
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•Conventional polarimetry measures ensemble far-field linear circular dichroism.•New techniques detect nonlinear and near-field optochirality at the ensemble level.•Spatially-resolved techniques probe local chirality of single nanostructures.•Dark-field microscopy measures single-particle circular differential scattering.
Chiral plasmonic nanomaterials can have circular dichroism and optical rotatory dispersion effects orders of magnitude larger than those observed in ordinary chiral molecules. Understanding this fascinating class of materials has proved challenging and has motivated several research groups to develop entirely new experimental techniques for characterizing chirality driven optical properties. In this review, we first describe the classical method of circular dichroism which measures linear, far-field responses from an ensemble population. We then go on to describe several of the more recently developed methods to probe chiral nanostructures as they expand into the domains of non-linear, near-field, and single particle measurements including spatially and spectrally resolved techniques.