• FRET;
  • micelles;
  • quantum dots;
  • ultrafast spectroscopy;
  • vibronic fine structures


Picosecond-resolved Förster resonance energy transfer (FRET) from various vibronic bands in benzo[a]pyrene (BP) shows a strong dependency on the spectral overlap of an energy acceptor in a confined environment. Our study on the dipolar interactions between BP and different acceptors, including ethidium (Et), acridine orange (AO), and crystal violet (CV), at the surface of a model anionic micelle revealed that the Förster distance (R0) and the rate of energy transfer is dependent on the individual spectral overlap of the vibronic bands of BP with the absorption spectra of the different energy acceptors. The differential behavior of the vibronic bands is compared with that of different dyes [quantum dots (QDs)] in a “dye-blend” (mixture) under FRET to an energy acceptor. Comparison of the FRET of the QDs with that of BP confirmed the independent nature of the dipolar interaction of the vibronic bands with other organic molecules, and the use of deconvolution techniques in the interpretation of the donor–acceptor (D–A) distance was also justified. We also showed that the consideration of differential FRET from the vibronic bands of BP and from the QDs in the dye-blend is equally acceptable in theoretical frameworks including the Infelta–Tachiya model and D–A distribution analysis in nanoenvironments.