Plasmonic ratchet wheels: switching circular dichroism by arranging chiral nanostructures

Nano Lett. 2009 Nov;9(11):3945-8. doi: 10.1021/nl9021623.

Abstract

We demonstrate circular dichroism (CD) in the second harmonic generation (SHG) signal from chiral assemblies of G-shaped nanostructures made of gold. The arrangement of the G shapes is crucial since upon reordering them the SHG-CD effect disappears. Microscopy reveals SHG "hotspots" assemblies, which originate in enantiomerically sensitive plasmon modes, having the novel property of exhibiting a chiral geometry themselves in relation with the handedness of the material. These results open new frontiers in studying chirality.