Tailoring Plasmonics of Au@Ag Nanoparticles by Silica Encapsulation
Abstract
Hybrid metallic nanoparticles encapsulated in oxide shells are currently intensely studied for plasmonic applications in sensing, medicine, catalysis, and photovoltaics. Here, we introduce a method for the synthesis of Au@Ag@SiO cubes with a uniform silica shell of variable and adjustable thickness in the nanometer range; and we demonstrate their excellent, highly reproducible, and tunable optical response. Varying the silica shell thickness, we could tune the excitation energies of the single nanoparticle plasmon modes in a broad spectral range between 2.55 and 3.25\,eV. Most importantly, we reveal a strong coherent coupling of the surface plasmons at the silver-silica interface with the whispering gallery resonance at the silica-vacuum interface leading to a significant field enhancement at the encapsulated nanoparticle surface in the range of 100\,\% at shell thicknesses 20\,nm. Consequently, the synthesis method and the field enhancement open pathways to a widespread use of silver nanoparticles in plasmonic applications including photonic crystals and may be transferred to other non-precious metals.
Keywords
Cite
@article{arxiv.2105.13946,
title = {Tailoring Plasmonics of Au@Ag Nanoparticles by Silica Encapsulation},
author = {Johannes Schultz and Felizitas Kirner and Pavel Potapov and Bernd Büchner and Axel Lubk and Elena Sturm},
journal= {arXiv preprint arXiv:2105.13946},
year = {2025}
}