Abstract:
—Singlet–singlet energy transfer between molecules of fluorescein and oxazine dyes in Langmuir–
Blodgett films is studied experimentally. The dependence of the energy-transfer efficiency on the distance
shows that the quenching of the donor fluorescence is the most efficient when the layers of the donor and
acceptor molecules are in a direct contact. An increase in the distance between the donor and acceptor layers leads to a decrease in the energy-transfer efficiency. To establish the mutual orientation of the donor and acceptor molecules, quantum-chemical calculations of the energy transfer process in the donor–acceptor
pair are carried out. The calculations show that the best correlation of the experimental and calculated values of the energy-transfer efficiency is observed when the interacting particles are shifted relative to each other by
about ~0.12 nm in parallel planes. The presented approach can be used to estimate the relative orientation of interacting particles in multimolecular ensembles.
