  The practical applications of chiral discrimination are usually limited by
the weak chiral response of enantiomers and the high complexity of detection
methods. Here, we propose to use the C lines (i.e., lines of polarization
singularities) emerged in light scattering by a metal sphere to detect small
chiral particles. Using full-wave numerical simulations and analytical
multipole expansions, we determined the absorption dissymmetry of
deep-subwavelength helices (i.e., chiral particles) at different positions on
the C lines. We find that the absorption dissymmetry can be much larger than
that induced by circularly polarized plane wave excitation, and it can be
attributed to the asymmetric absorption of the induced electric and magnetic
dipoles. We also show that the absorption dissymmetry strongly depends on the
anisotropy of the helices. The results may find applications in optical
manipulations, optical sensing, and chiral quantum optics.
