Excited-State Dynamics in Rigid Media: Evidence for Long-Range Energy Transfer
2013
Ito, Akitaka | Stewart, D. J. | Knight, Troy E. | Fang, Zhen | Brennaman, M Kyle | Meyer, Thomas J.
In semirigid PEG-DMA550 films with the added anthracene derivatives PEG-An and Acr-An, energy transfer quenching of the metal-to-ligand charge transfer excited state Ru(bpy)₃²⁺* to give −³An occurs by both rapid, static, and slow, diffusional quenching processes. The appearance of −³An was verified by transient absorption measurements. The kinetics of the two quenching processes have been analyzed by a Stern–Volmer kinetic analysis. The data for static quenching are consistent with energy transfer quenching with a distance dependence consistent with Dexter (exchange) energy transfer. On the basis of this analysis Bohr radii were found to be 26 and 11 Å for PEG-An and Acr-An, respectively. Evidence for triplet–triplet annihilation between triplet anthracene excited states in the films was obtained from the concentration dependences of excited-state decay. These results provide evidence for long-range energy migration between derivatized anthracenes in rigid, cross-linked PEG-DMA550 films.
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