Circular dichroism measurement of a single anisotropic chiral nanostructure using scanning circular dichroism microscopy

Abstract

Circular dichroism (CD) spectroscopy is widely used to study the chiroptical properties of chiral materials, including films, solutions, and isotropic materials. However, measuring the CD signal of single anisotropic chiral nanostructures is challenging due to the presence of “artifact” signals, such as linear dichroism (LD) and linear birefringence (LB). In this study, we employed scanning circular dichroism microscopy (SCDM) to extract the intrinsic CD signal of the single DBD/LBL self-assembled chiral supramolecule. Using the Stokes–Mueller formalism, we analyzed the SCDM signal, which exhibited a sinusoidal dependence on the polarization angles of the laser beam. This approach enabled the determination of both the orientation and the intrinsic CD. The intrinsic CD of the single DBD self-assembled chiral supramolecule was 9.9 mdeg, while that of the single LBL self-assembled chiral supramolecule was −9.3 mdeg. SCDM provides a new method for measuring CD at the nanoscale, paving the way for future advancements in optoelectronic applications and introducing an approach for studying chiral nanomaterials.