Au/Ag bimetallic nanocomposites as a highly sensitive plasmonic material

TL;DR

This paper introduces Au/Ag bimetallic nanocomposites as highly sensitive plasmonic materials, demonstrating their superior sensitivity and figure-of-merit through numerical modeling, suitable for advanced nanoplasmonic sensing applications.

Contribution

The study presents a novel numerical approach to analyze Au/Ag bimetallic nanocomposites, revealing their enhanced plasmonic properties and potential for improved sensing technologies.

Findings

Bimetallic nanocomposites exhibit dual plasmon resonance peaks converging to a single peak.

Sensitivity and figure-of-merit are approximately 3 and 4.3 times higher than conventional plasmonic materials.

Effective unit size below 2.5 nm enables strong plasmonic coupling in nanocomposites.

Abstract

We report Au/Ag bimetallic nanocomposites as a highly sensitive plasmonic material. A unit approach via a three-dimensional numerical modeling is introduced to observe collective plasmon resonance in Au/Ag bimetallic nanocomposites as well as Au mono-metallic nanoensembles. Au nanoensembles provide consistently identical plasmon wavelength, independent of inter-unit distance. In analogy with mono-metallic nanoensembles, Au/Ag bimetallic nanocomposites distinctly feature converging dual plasmon resonance peaks to a single plasmon resonance peak, strongly depending on the packing density and the unit size. An effective unit size of bimetallic nanocomposites is below 2.5 nm in a subwavelength structure, which is small enough to feature bimetallic nanocomposites. As a result, the Au/Ag bimetallic nanocomposites clearly show exceptionally high sensitivity and figure-ofmerit (approximately 3 fold of conventional plasmon sensitivity and 4.3 fold of conventional plasmon FOM), resulting from coupled Au-Ag quadrupole bimetallic nanounits. This study provides essential rationales for Au/Ag bimetallic nanocomposites serving as a desirable and alternative plasmonic material for advanced nanoplasmonic sensing technologies.