Photofabrication of chiral plasmonic nanospiroids
Koki Shimomura, Yuma Nakane, Takuya Ishida, Tetsu Tatsuma
Abstract
Nanofabrication of three-dimensional chiral plasmonic structures has been a challenging research topic. In the present study, we shaped dielectric caps on plasmonic gold nanocubes (AuNCs) into three-dimensional nanospiroids by circularly polarized light (CPL) as the chirality source, without using lithographic methods or chiral molecules. AuNCs adsorbed on a TiO2 substrate were irradiated with right or left CPL in the presence of Pb2+ for the deposition of PbO2 on AuNCs. The Au–PbO2 nanocomposites, thus, obtained are the first spiral plasmonic nanostructures prepared by CPL. They exhibit strong and sharp signals of circular dichroism, and the signs of the signals are reversed by changing the rotation direction of the CPL used. Their g-factor values are highest among the chiral plasmonic nanostructures fabricated by CPL.