| Abstract
| - For distance measurements the fluorescence relaxation was explored within pairwise interacting chemicallyidentical, but photophysically different fluorescent groups. The recently developed theory (Kalinin, S. V.;et al. Spectrochim. Acta, Part A2002, 58, 1087−1097) of partial donor−donor energy migration (PDDEM)was tested on lipid vesicles as a model system, which, for example, enables arrangement of a pH gradientbetween the inside and outside of the lipid bilayer. Time-correlated single-photon counting and steady-statefluorescence experiments were performed on mono- and bis-lipid derivatives of fluorescein solubilized inlipid bilayers. The PDDEM approach was successfully applied in the analyses of the different experiments.The distances extracted between the fluorescein groups of bis-fluorescein derivatives in lipid vesicles composed1,2-dioleoyl-sn-glycero-3-phosphocholine and 1,2-dimyristoyl-sn-glycero-3-phosphocholine were found to bein reasonable agreement with independent measurements of the bilayer thickness.
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