  Nanoscopic observation of chiro-optical phenomena is essential in wide
scientific areas but has measurement difficulties; hence, its physics are still
unknown. Currently, in most cases, chiro-optical phenomena have been
investigated by polarized light handling far-field measurements or via
predictions by theoretical simulations. To obtain a full understanding of the
physics of chiro-optical systems and derive the full potentials, it is
essential to perform in situ observation of the chiro-optical effect from the
individual parts because the macroscopic chiro-optical effect cannot be
translated directly into microscopic effects. In the present study, we observed
the chiro-optical responses at the nanoscale level by detecting the
chiro-optical forces, which were generated by illumination of the
material/probe system with circularly polarized light. The induced optical
force was dependent on the handedness of the incident circularly polarized
light and well correlated to the electromagnetically simulated differential
intensity of the longitudinal electric field. Our results facilitate the
clarification of chiro-optical phenomena at the nanoscale level and could
innovate chiro-optical nanotechnologies.
