Revealing the effect of plasmon transmutation on charge transfer plasmons in substrate-mediated metallodielectric aluminum clusters

Aluminum nanoparticle nanocomplexes have extensively been utilized for sustaining ultrastrong plasmonic bonding and antibonding resonant modes across the ultraviolet to visible spectrum. In this study, we analyze the plasmon response for two conventional symmetric heptamer and antisymmetric octamer antennas mediated by conductive film as a substrate to induce very sharp Fano-resonant mode at the high energy states. Besides, presence of an underlying conductive film in touching regime with the plasmonic nanoantennas leads to formation of charge transfer plasmons (CTPs) across the deep-UV band. It is also shown that presence of dielectric carbon nanospheres in the gap spots between proximal nanodisks gives rise to breaking the symmetry of the assemblies, while the new magnetic multipolar modes are induced and divided the Fano dip in two parts as well as formation of a couple of charge transfer plasmon resonant shoulders. The compactness and geometries of the clusters allow for inducing substantially strong resonant modes across the deep-UV domain. Our investigations provide new pathways and features for designing multifunctional molecular probes, biochemical sensors, and cathodoluminescence antennas across the UV spectrum. The proposed analysis were done using a blend of Finite-Difference Time-Domain (FDTD) calculations and transfer of plasmonic charges in nanoscale systems.