Probing plasmonic coupling and symmetry breaking in silver nanoprism dimers

• EELS simulations reveal plasmon coupling in solid, hollow, and asymmetric Ag nanoprism dimers. • Asymmetric dimers (SHND) create a hybrid BDP mode at an intermediate energy. • Structural asymmetry causes spatial mode localization, confining higher-order modes. • BDP energy is tuned by inter-particle gap and internal cavity size. • SHNDs function as directional nanoantennas or selective nanoreactors via asymmetric near-fields. This study theoretically investigates the plasmonic behavior of coupled silver triangular nanoprism dimers using Electron Energy Loss Spectroscopy (EELS) simulations, comparing three distinct configurations: solid-solid (SSND), hollow-hollow (HHND), and asymmetric solid-hollow (SHND). The results show that the primary plasmon resonance in the hollow dimer is significantly redshifted compared to the solid dimer due to reduced tip polarizability. The asymmetric dimer exhibits an intermediate resonance resulting from plasmon hybridization. Most importantly, the structural asymmetry in the SHND localizes energy, confining specific modes to either the solid or hollow component. This unique property allows these asymmetric dimers to function as directional nanoantennas or selective “nanoreactors.” This research provides a valuable framework for designing complex plasmonic structures with on-demand optical properties for applications like enhanced spectroscopy and photocatalysis.