Nanoporous gold leaves: plasmonic behavior in the visible and mid-infrared spectral regions

TL;DR

This paper introduces a new method for preparing self-standing nanoporous gold leaves, enabling detailed optical and plasmonic analysis across ultraviolet to mid-infrared wavelengths, revealing potential applications in infrared plasmonics.

Contribution

It presents a novel self-standing nanoporous gold leaf fabrication method and analyzes its plasmonic behavior in a symmetric configuration across a broad spectral range.

Findings

Nanoporous gold exhibits metallic behavior at higher wavelengths.

The self-standing leaves support symmetric and antisymmetric plasmonic modes.

Potential for infrared plasmonic applications is demonstrated.

Abstract

A robust and reproducible preparation of self-standing nanoporous gold leaves (NPGL) is presented, with optical characterization and plasmonic behaviour analysis. Nanoporous gold (NPG) layers are tipically prepared as thin films on a bulk substrate. Here we present an alternative approach consisting in the preparation of NPGL in the form of a self-standing film. This solution leads to a perfectly symmetric configuration where the metal is immersed in a homogeneous medium and in addition can support the propagation of symmetric and antisymmetric plasmonic modes. With respect to bulk gold, NPG shows metallic behaviour at higher wavelengths, suggesting possible plasmonic applications in the near / medium infrared range. In this work the plasmonic properties in the wide wavelength range from the ultraviolet up to the mid-infrared range have been investigated.