Continuously tuning the spectral response of chiral plasmonic patchy particles through galvanic replacement reaction

Abstract

We demonstrate the continuous tuning of the circular dichroism spectra of chiral patchy particle structures fabricated by dynamic shadowing growth (DSG) using the galvanic replacement reaction (GRR), which is a wet chemical process where Au ions in solution are gradually replaced by Ag atoms in a support. It is found that the unpolarized and circular polarization optical responses generally shift to longer wavelengths as a function of reaction time. The red-shifts in the spectra are attributed to changes in the ambient refractive index, chiral patch morphology, and material composition. For reaction times less than 4 minutes, the circular dichroism spectra can be adjusted over a wide range of wavelengths in the visible and near-infrared region with only slight reductions in magnitude. Thus, the combination of dry (DSG) and wet (GRR) nanofabrication techniques offers a route to dynamically tune the spectral response of chiral plasmonic thin films.