  We investigate the chiroptical response of a single plasmonic nanohelix
interacting with a weakly-focused circularly-polarized Gaussian beam. The
optical scattering at the fundamental resonance is characterized
experimentally, and the chiral behavior of the nanohelix is explained based on
a multipole analysis. The angularly resolved emission of the excited nanohelix
is verified experimentally and it validates the theoretical results. Further,
we study the first higher-order resonance and explain the formation of chiral
dipoles in both cases.

Optics