Shape and Size-Dependent Surface Plasmonic Resonances of Liquid Metal Alloy (EGaIn) Nanoparticles

Liquid metals (LM) are emerging plasmonic nanomaterials with transformable surface plasmon resonances (SPR) due to their liquid-like deformability. This study delves into the plasmonic properties of LM nanoparticles, with a focus on EGaIn (eutectic gallium-indium)-based materials. Leveraging Finite-Difference Time-Domain (FDTD) simulations and experimental validations for spherical liquid metal nanoparticles plasmonic properties, we explored the localized SPR (LSPR) effects of EGaIn nanoparticles with various shapes, including nanospheres, dimers, nanorods, nanodisks, nanoellipses, nanocubes, and nanocuboids, in the broad range of ultraviolet (UV)-visible-near infrared (NIR) spectrum. While EGaIn is conventionally known as a UV-active metal alloy, this study reveals unique LSPR features of EGaIn (e.g., higher order resonances, polar and quadrupolar modes) in the broader visible and NIR wavelength ranges, providing a comprehensive map of LSPR properties for different shapes of EGaIn nanoparticles. These findings offer new insights into the dependence of the optical properties of EGaIn nanoparticles on their geometries for diverse applications, ranging from biosensing, nanoelectronics, to optomechanical systems.