Optical Detection of Single Sub-15 nm Objects Using Elastic Scattering Strong Coupling

Small metallic nano-objects play crucial roles in diverse fields, including biomedical imaging, nanomedicine, spectroscopy, and photocatalysis. However, detecting the light scattered by sub-15 nm nano-objects is still a challenge due to the low scattering cross-section. Here, we introduce a technique to detect single nano-objects using strong coupling of a plasmonic nanocavity to the nano-object. Our results show that the spectral signatures of down to 1.8 nm nano-objects can be detected due to the enhanced, modified scattering by the nanocavity.