Plasmonic modes of gold nano-particle arrays on thin gold films

TL;DR

This paper investigates gold nanoparticle arrays on thin gold films to identify asymmetric plasmonic modes with enhanced field confinement, exploring their optical properties and effects of thermal treatment for biosensing applications.

Contribution

It introduces a novel geometry of gold nanoparticle arrays on thin gold films and analyzes their plasmonic modes and the impact of thermal treatment on optical properties.

Findings

Identification of asymmetric surface plasmon modes with improved field confinement

Thermal treatment modifies gold's crystalline structure, affecting optical responses

Optical extinction spectroscopy reveals mode characteristics

Abstract

Regular arrays of metal nanoparticles on metal films have tuneable optical resonances that can be applied for surface enhanced Raman scattering or biosensing. With the aim of developing more surface selective geometries we investigate regular gold nanoparticle arrays on 25nm thick gold films, which allow to excite asymmetric surface plasmon modes featuring a much better field confinement compared to the symmetric modes used in conventional surface plasmon resonance setups. By optical extinction spectroscopy we identify the plasmonic modes sustained by our structures. Furthermore, the role of thermal treatment of the metal structures is investigated, revealing the role of modifications in the crystalline structure of gold on the optical properties.