Twin-donor systems for resonance energy transfer

Resonance energy transfer involving two identical donors and one acceptor is modelled by quantum electrodynamical calculation. The results account for recent experimental observations of simultaneous excitation energy transfer in the photochemistry of organic dyes. It is shown that a family of three energy transfer mechanisms has to be considered in order to describe fully the energy pooling phenomenon. The chromophore architecture has a pivotal role in determining the dominant mechanism.