Detection of energy transfer mechanisms in nanoscopic optical rulers

Understanding the energy transfer dynamics in fluorescein-gold nanoparticle systems is crucial for future optoelectronic devices based on energy transfer. Dominant energy transfer mechanisms including the dipole-dipole (FRET) and dipole-surface energy transfer (SET) are investigated. We have compared the measured performance values with the theoretical predictions for both FRET and SET models, specifically the importance of interactions between various scales. It has been shown that the highly sensitive FRET process is limited and focused on the Förster radius range (R₀), while the high efficiency of the SET over longer distances provides better resolution than the FRET process. The detection and quantitation of the energy transfer mechanism might be to playing a critical role in improving spatial resolution, distance range, and spectral sensitivity for biophysical studies.