Nonlocal Optical Response of Particle Plasmons in Single Gold Nanorods

Particle plasmons in metal nanoparticles have primarily been investigated through the use of local optical response approximations. However, as nanoparticle size approaches the average distance of electrons to the metal surface, mesoscopic effects such as size-dependent plasmon linewidth broadening and resonance energy blue shifts are expected to become observable. In this work, we compared the experimental spectral characteristics with simulated values obtained using a generalized nonlocal optical response theory-based local analogue model. Our results show that the nonlocal plasmon damping effects in single nanoparticles are less significant compared to those observed in plasmon-coupled systems. Moreover, our study demonstrates that single-particle dark-field spectroscopy is an effective tool for investigating the nonlocal optical response of particle plasmons in single nanoparticles. These results have important implications for the rational design of novel nanophotonic devices.