Enhancement and Suppression of Resonance Energy Transfer near Metal Nanoparticles

Plasmons are known to promote light-matter interaction, providing a powerful tool to increase the rate of energy transfer between donor and acceptor molecules that are appropriately located near a plasmonic particle, a phenomenon called plasmon-coupled resonance energy transfer (PC-RET). In this work, we utilize a Mie theory-based method to calculate the PC-RET rate for a donor-Acceptor pair interacting with a single spherical particle, with the goal of identifying key geometrical factors in plasmonic systems that determine the RET rate. We also determine the plasmon enhancement contribution to absorption by the donor, and then combine this with the RET efficiency to determine plasmon enhancement to the overall acceptor formation rate. We find that the RET is often suppressed by coupling to plasmons on a single-molecule level although plasmon-enhanced absorption can lead to a net increase in acceptor formation rate in the presence of the nanoparticle. A quasistatic analysis reveals the dependence of multipolar contributions on the distance of the fluorophores from the metal particle. Finally, it is demonstrated from an analysis of experimental RET results that the structure of a nanophotonic system can be determined from the sensitivity of the RET rate to the system geometry.