Creating Chiral Plasmonic Nanostructures with Circularly Polarized Light

Chiral plasmonic nanostructures have attracted much interest in recent years as new platforms for polarization modulation. Other than photonic devices, chiral plasmonic nanostructures facilitate the ultrasensitive detection of chiral biological materials, e.g. DNA. To synthesize chiral plasmonic nanostructures, the most well-established method is chirality transfer from biological materials to the inorganic nanostructures. Alternatively, circularly polarized light can be used to control the formation of the plasmonic enantiomeric nanostructures, where the chirality of the product is solely defined by the polarization of the light. This synthesis method may be more cost-effective while allowing the wavelength and intensity of light to be used as tunable parameters. Here we investigate the use of circularly polarized light to create chiral gold nano bipyramids. Hot charge carriers can be generated with light and consumed to fabricate chiral plasmonic structures. Scanning electron microscopy (SEM) coupled with cathodoluminescence measurements comparing the nano bipyramids before and after circularly polarized light illumination is used for characterization. We will show that both dielectric or plasmonic chiral additions can be deposited depending on the identity of reagents. Circular dichroism (CD) spectra of the chiral plasmonic nanostructures further demonstrate the polarization dependent light-matter interaction of the materials synthesized.