Polarization and Decay of Fluorescence of Solutions

Abstract

Measurements of the polarization and the mean decay periods τ∥ and τ⟂ of fluorescence components I∥ and I⟂ parallel and perpendicular to the electric vector of plane polarized exciting light were performed for uranin dye solutions in glycerol diluted with methyl alcohol, ethyl alcohol and water. From these measurements the volume ν of the dye molecule together with its solvation shell and the limiting emission anisotropy r0 for solutions of various viscosities were calculated. Both ν and r0 appeared to be in general not constant and dependent on the nature of the solvent. If, as observed in one case, ν and r0o are substantially constant, a good agreement between experimental values τ∥/τ and τ⟂/τ and those evaluated from the equations of JABLONSKI is obtained (τ being the mean duration of the fluorescence emitted in all directions).