Förster Resonance Energy Transfer and Molecular Fluorescence near Gain Assisted Refractory Nitrides Based Plasmonic Core-Shell Nanoparticle

Abstract

The process of Forster resonance energy transfer (FRET) and molecular fluorescence (MF) plays a vital role in protein–protein interaction, detection of nucleic acids, photochemistry, molecular spectroscopy, forensics, fingerprinting, photovoltaics, etc., to name only a few. The present work focus on developing closed form expressions for FRET enhancement, fluorescence yield (FY), and quantum yield (QY) in the presence of core-shell nanoparticle (CSNP) consisting of dielectric core and metallic shell. It is shown that the plasmonic nanoparticle enhance the FRET significantly only when the donor and acceptor molecules are far apart. When both molecules are closely placed (~ 1 nm), plasmonic nanoparticle does not enhance the FRET significantly. Therefore, when acceptor–donor molecules of chromophore are closely placed, significant FRET enhancement cannot be realized via molecule–surface plasmon interaction. The present work shows that this problem can be resolved by incorporating optical gain in the dielectric core of CSNP, and this is an effective mechanism for enhancing molecular interaction when donor–acceptor molecules are closely placed. In addition to FRET, molecular fluorescence in the presence of CSNP is also studied. The well-established Gersten-Nitzan model is extended to derive closed form expressions for FRET, FY, and QY, albeit near core-shell nanoparticle. Notably, gigantic enhancement in FRET and FY by virtue of loss compensation is accompanied by reduction in resonance linewidth. Refractory nitrides (e.g., ZrN and TiN) based CSNPs are assessed for their feasibility in enhancing FRET, and FY and performance comparison with Au is also presented.