Intrinsic and Extrinsic Circular Dichroism in Linear Arrays of Anisotropic Chiral Nanoparticles

Controlling the collective optical properties of chiral plasmonic systems is essential for advancing photonic and chiral sensing technologies. Using template-assisted self-assembly, we engineered one-dimensional chiral plasmonic linear arrays composed of highly anisotropic chiral gold nanoparticle chains in an end-to-end configuration, achieving tunable plasmonic and chiroptical properties. While isolated chiral NPs exhibit intrinsic plasmonic circular dichroism (CD), their periodic arrangement introduces surface lattice resonances, yielding sharp extrinsic CD peaks. Orientation- and angle-dependent CD measurements enable a clear differentiation between intrinsic and extrinsic CD contributions. Notably, at specific angles of incidence, the assembled arrays exhibit a significant enhancement in the chiroptical response, demonstrating the dynamic tunability of their optical activity. The chiroptical properties of the arrays can be transferred to a luminescent dye, thereby yielding circularly polarized emission. These chiral superlattices supporting intrinsic and extrinsic chiroptical properties offer a robust platform for photonic devices, ultrasensitive chiral sensing, and enantioselective applications.