title: Determining a fluorophore's transition dipole moment from fluorescence lifetime measurements in solvents of varying refractive index.
abstract: The transition dipole moment of organic dyes PM546 and rhodamine 123 is calculated from fluorescence lifetime measurements in solutions of different refractive index. A model proposed by Toptygin et al (2002 J. Phys. Chem. B 106 3724-34) provides a relationship between the radiative rate constant and refractive index of the solvent, and allows the electronic transition dipole moments to be found: it is (7.1  ±  1.1) D for PM546 which matches that found in the literature, and (8.1  ±  0.1) D for rhodamine 123. Toptygin's model goes further in predicting the shape of the fluorescent dye and here we predict the shape of PM546 and rhodamine 123 to be ellipsoidal.
authors.affiliation: Department of Physics, King's College London, Strand, London, WC2R 2LS, UK.
authors.forename: Pei-Hua
authors.initials: PH
authors.lastname: Chung
authors.forename: Carolyn
authors.initials: C
authors.lastname: Tregidgo
authors.forename: Klaus
authors.initials: K
authors.lastname: Suhling