Study of plasmon resonance in a gold nanorod with an LC circuit model

TL;DR

This paper models the plasmon resonance of gold nanorods using an LC circuit analogy, revealing dependencies on aspect ratio and radius, and analytically deriving scattering and absorption cross sections.

Contribution

It introduces a novel LC circuit model for gold nanorods, providing analytical expressions for resonance wavelength and extinction spectra, enhancing understanding of light-nanoparticle interactions.

Findings

Resonance wavelength depends on aspect ratio and radius.

Analytical formulas for scattering and absorption cross sections.

Lorentzian line-shape for extinction spectrum.

Abstract

Gold nanorod has generated great research interest due to its tunable longitudinal plasmon resonance. However, little progress has been made in the understanding of the effect. A major reason is that, except for metallic spheres and ellipsoids, the interaction between light and nanoparticles is generally insoluble. In this paper, a new scheme has been proposed to study the plasmon resonance of gold nanorod, in which the nanorod is modeled as an LC circuit with an inductance and a capacitance. The obtained resonance wavelength is dependent on not only aspect ratio but also rod radius, suggesting the importance of self-inductance and the breakdown of linear scaling. Moreover, the cross sections for light scattering and absorption have been deduced analytically, giving rise to a Lorentzian line-shape for the extinction spectrum. The result provides us with new insight into the phenomenon.