“…Electronic excitation energy transport by the dipole–dipole Förster mechanism is a very important physical process taking place in the nanoscale up to 10 nm. Therefore, it is an effective tool to tailor, study, and describe many special systems such as nanoparticles, quantum dots, plasmonic platforms, aggregated systems, colloids, or specific ordered systems. − It can also provide relevant information about the characteristics of biologically important systems, such as end-to-end protein distance, diffusion, and conformations of fragments of macromolecules, DNA, enzymes, or albumins and serve as an efficient tool in biosensor design. − In many cases, Förster resonance energy transfer (FRET) occurs in a single step from an excited donor to an unexcited acceptor. Such a situation is, for example, typical of a macromolecule labeled by a single donor and single acceptor or more generally for the concentration of donors much lower than that of acceptors.…”