Picosecond studies of energy transfer of donor and acceptor dye molecules in solution. II. A concentration dependence

The energy transfer between donor and acceptor molecules has been studied by steady-state and picosecond time-resolved spectroscopies in solutions with a given concentration of donor molecules and different concentrations of acceptor molecules. The rise and decay times of the fluorescence from donor and acceptor molecules were measured. The decrease of the decay times of the donors and the rise time of the acceptors with an increase of the concentration of acceptors observed in the mixed solution indicates a faster energy-transfer rate between the donors and acceptors. Theoretically calculated fluorescence profiles and efficiencies of energy transfer are in agreement with the experimental results.