Theory of energy transfer interactions between a pair of two level molecules in the molecular
nanojunction including surface plasmon (SP) dressed interaction of plasmonic nanostructure,
replicating metallic leads is presented. Results on the modification of bare dipolar interaction,
known to be responsible for molecular energy transfer processes, in the proximity of metallic
nanosystem are presented. Specifically, the manuscript includes theoretical investigation of
nanosphere (NSP) monomer, nanoshell (NSH) monomer, and coupled nanosphere pair (dimer)
based nanosystems. Closed form analytical expressions for NSP and NSH structures tailored for molecular nanojunction geometry are derived in the theoretical framework of multipole spectral expansion (MSE) method, which is straightforwardly extendible to dimers and multimers. The role of size and dielectric environment on energy transfer is investigated and interpreted. Theory predicts
that the monomer and dimer both enhance the dipolar interaction, yet, dimer geometry is favorable due to its spectral tuning potential originated from plasmon hybridization and true resemblance with typical molecular nanojunctions.