Non-local Quantum Plasmon Resonance in Ultra-small Silver Nanoparticles

Understanding the mechanisms of light-matter interactions in ultra-small plasmonic nanoparticles (USNP) represents a major challenge because of the importance of size dependence and quantum effects. The plasmon resonance in such small metallic nanoparticles (< 5 nm) exhibits substantial deviation from classical theory predictions, with evident frequency shifts to a higher energy. This is due to the quantum nature of the free charge carriers and the dynamic response of metallic nanoparticle to the self-consistent electromagnetic fields. Such phenomena have so far been poorly understood in experiments while classical theory has mostly focused on nanostructures and sidestepped the size dependence. Here we report a quantum mechanical model of the metal permittivity to describe the USNP behaviour and experimental evidence. The proposed non-local quantum model of the permittivity for the propagation of plasmon waves in quantum-confined silver nanoparticles has no size limitations in the UNSP range.

Automated summary

Understanding the mechanisms of light-matter interactions in ultra-small plasmonic nanoparticles (USNP) is a challenging task due to the quantum effects and size dependence. The plasmon resonance in small metallic nanoparticles exhibits deviation from classical theory predictions, with noticeable frequency shifts to higher energy levels. This is attributed to the quantum nature of free charge carriers and the dynamic response of metallic nanoparticles to electromagnetic fields.