Using single molecule fluorescence spectroscopy we have investigated fluorescence resonance energy transfer (FRET) occurring between two peryleneimide (PI) chromophores in a series of synthetic systems: PI end-capped fluorene trimers, hexamers and polymers for which the interchromophoric distance vary from 3.4 to 5.9 and 42 nm, respectively. By monitoring in parallel the fluorescence intensity and the number of independent emitting chromophores from each molecule, we could discriminate between competitive Foerster-type energy transfer processes such as energy hopping, singlet-singlet annihilation and singlet-triplet annihilation for the PI end-capped fluorine compounds. Due to different energy transfer efficiencies, variations in the interchromophoric distance enable switching between these processes. The single molecule fluorescence data reported here suggest that similar energy transfer pathways have to be considered in the analysis of single molecule trajectories of donor/acceptor pairs, as well as in the case of more complex systems like natural multichromophoric systems, such as light harvesting antennas or oligomeric fluorescent proteins.

Date Published: 1 July 2004
PDF: 9 pages
Proc. SPIE 5322, Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues II, (1 July 2004); doi: 10.1117/12.531322

Published in SPIE Proceedings Vol. 5322:
Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues II
Dan V. Nicolau; Joerg Enderlein; Robert C. Leif; Daniel L. Farkas, Editor(s)