Chiral hotspots via hollow silicon nanoparticles illuminated by vector Bessel beams

In areas such as drug synthesis and purification, discrimination between the enantiomers is of great importance. Chiral hotspots-which enhance chiroptical signals from molecules via generation of superchiral near fields-enable low detection limits. In this vein, we study the interaction of a superchiral Bessel beam and an oligomer composed of hollow silicon nanoparticles. We find that imperfections in the positioning of the nanoparticles and the chiral molecule are not disruptive. The electromagnetic field at the center of the quadrumer may be more superchiral than the incident field. Superchirality enhancement factors as large as 20 - 146 are achievable. Moreover, the peak of the superchirality enhancement can be shifted about 400 nm via the hollow size. Such chiral hotspot holds promise for circular dichroism spectroscopy of a specific molecule.