Down-chain energy migration

Down-chain energy migration has since been widely investigated experimentally and confirmed, and is now known to be a common phenomenon that plays a significant role in the degradation and stabilization of polymers, including those... 

In PPDA, the chromophores are part of the polymer backbone, and since they are not adjacent to each other, down-chain energy migration is not possible. Interestingly, when a dilute solution of this polymer is irradiated, a certain amount of excimer fluorescence is observed along with the predominant... 

Here, ko is the unimolecular decay rate constant of the excited donor, and Rq is the critical distance between D and A, at which the probabilities of spontaneous deactivation and of energy transfer are equal. Typical Rq values are listed in Table 1.3, which also includes values for self-transfer [14]. The latter process is of relevance for down-chain energy transfer (energy migration), which is referred to below. 

---