Energy Transfer Between Dye Molecules Investigated by Steady State and Time Resolved Spectroscopy.
The kinetics of long range resonant energy transfer between photoexcited dye molecules (the donor) and unexcited dye molecules (the acceptor) has been studied with the goal to understand the fundamental processes behind long range resonant energy transfer, to search for the possible mechanisms during the energy transfer, and to find out the factors which parameters affect the energy transfer between the donor and acceptor molecules. A theoretical model based on the dipole-dipole interaction was established to explain the dynamics of energy transfer between the donor and acceptor dye molecules and fit the kinetic fluorescence profiles of donor and acceptor emission. The measurements by the techniques of steady state and time-resolved fluorescence spectroscopy were performed for the binary mixtures (A) Rhodamine 6G (the donor) and Oxazine 4 Perchlorate (the acceptor), and (B) Rhodamine B (the donor) and Nile Blue A Perchlorate (the acceptor). It is found that: (1) Not only was the donor decay time short but also the acceptor risetime slowed in the mixed solution. (2) The relative decrease of donor quantum yield followed the increase of quantum yield of acceptor when the energy transfer is operative. (3) The decrease of donor decay time followed the increase of the risetime of the acceptor as the concentration of acceptor increased for a given concentration of donor at room temperature. (4) The long range energy transfer rate increases as the concentration of acceptor and the energy deactivation efficiency increases as the diffusion coefficient increases. From the thesis research, the long range energy transfer via dipole-dipole interaction plays a dominant role in the mechanism of energy transfer between donor and acceptor binary system (R (TURN) 50(ANGSTROM)) and the diffusion of molecule helps in moving the donors and acceptors so that energy can be transferred more readily. The efficiency of energy transfer can be increased from 49% to 69% when the contribution of diffusion varies from 1% to 38%. Factors such as the typical transfer distance R(,0), the concentration and the decay times of donor and acceptor molecules, are important parameters which affect the efficiency and operation of energy transfer.
- Pub Date:
- March 1982
- Physics: Optics