Investigation of FRET from organic dyes to silver nanoparticles and structural properties using the DFT/TD-DFT approach

The Forster resonance energy transfer involving a fluorescence molecule and organic quencher is constrained to a distance of ∼10 nm. However, with the coupling plasmonic materials, a significant amount of energy transfer can take place over substantially larger separations. The authors have studied intermolecular interactions using the nonradiative energy transfer process between organic dyes as donors and silver nanoparticles as acceptors. DFT and TD-DFT calculations were used to explore the atomic charges and the related properties. Theoretically determined ground and excited state dipole moments indicated that the increase in excited state dipole moment was due to the intramolecular charge transfer (ICT) character in the dyes.