Discrete and dimeric chiral plasmonic nanorods: intrinsic chirality and extrinsic chirality

Abstract

The recent progress in chemical synthetic methodologies has facilitated the fabrication of discrete plasmonic nanoparticles exhibiting chiral characteristics on their surface. In comparison to conventional gold nanorods (NRs), such structures possess strong plasmonic circular dichroism response, making them highly suitable for various applications involving circularly polarized light. Although the intrinsic and extrinsic chirality of chiral nanostructures produced by the assembly with chiral ligands have been explored both experimentally and theoretically, the investigation into the influencing factors of the intrinsic and extrinsic chirality of discrete chiral Au NRs (dc-Au NRs) has been relatively limited. Herein, we conducted a comprehensive investigation using full-wave electromagnetic simulations to explore the influence of various structural parameters (such as helical depth, width, and numbers of the helical pitches) on the intrinsic and extrinsic chirality of dc-Au NRs. Additionally, we examined the chiral surface plasmon resonance coupling and the corresponding chiral near-field by studying the cross-like assembly of dc-Au NR dimers. These findings serve as valuable guidance for future experimental and theoretical research on chiral plasmonic nanostructures and their applications involving circularly polarized light.