Molecular-Induced Chirality Transfer to Plasmonic Lattice Modes

TL;DR

This study demonstrates that molecular chirality can be transferred to plasmonic lattice modes in nanoparticle arrays, enabling tunable control of optical activity through chiral molecule interaction.

Contribution

It reveals that molecular chirality transfer extends to collective plasmonic lattice modes, using self-assembled gold nanoparticle arrays embedded with chiral molecules.

Findings

Chiral molecules induce optical activity in lattice modes.

Circular dichroism peaks shift with lattice parameters.

Chirality transfer is explained by a coupling model.

Abstract

Molecular chirality plays fundamental roles in biology. The chiral response of a molecule occurs at a specific spectral position, determined by its molecular structure. This fingerprint can be transferred to other spectral regions via the interaction with localized surface plasmon resonances of gold nanoparticles. Here, we demonstrate that molecular chirality transfer occurs also for plasmonic lattice modes, providing a very effective and tunable means to control chirality. We use colloidal self-assembly to fabricate non-close packed, periodic arrays of gold nanoparticles, which are embedded in a polymer film containing chiral molecules. In the presence of the chiral molecules, the SLRs become optically active, i.e. showing handedness-dependent excitation. Numerical simulations with varying lattice parameters show circular dichroism peaks shifting along with the spectral positions of the lattice modes, corroborating the chirality transfer to these collective modes. A semi-analytical model based on the coupling of molecular and plasmonic resonances rationalizes this chirality transfer.