Cumulative Effect of Solvent and Ligand Dielectric around the Nanoparticles: Merging Past Century Theories into a Singular Scaling Equation

The brilliant colors of dispersions of metallic colloids have been fascinating since antiquity, long before our understanding of light-matter interactions. The ability of noble-metal colloids to manipulate light at the nanoscale has opened up the emerging research area called plasmonics. Metals are considered to be either conductors in electronics or reflectors in optics. The Drude model of electron conduction, which is an application of kinetic theory to electrons in a solid, was proposed in 1900 by Paul Drude to explain the transport properties of electrons in metals. On the other hand, in 1908, Gustav Mie published his seminal work on the simulation of the color effects connected with colloidal gold particles using the classical Maxwell equations, which is popularly known as Mie scattering theory. The physical origin of light absorption by metal nanoparticles is the coherent oscillation of the conduction-band electrons, coined as localized surface plasmon resonance (LSPR). The resonance frequency of this LSPR is strongly dependent on the size, shape, interparticle interactions, dielectric properties, and local environment of the nanoparticles. In this article, we aim to elucidate the epicenter of the sensitivity of the localized surface plasmon resonance to the local dielectric environments around the ligand-stabilized gold nanoparticles that merges the Drude electron conduction model and Mie scattering theory proposed from two different perspectives in the historical achievements of scientific discoveries.