EXCITON SPLITTING OF FLUORESCEIN DISODIUM IN POLYETHYLENE GLYCOL-600

The absorption and emission spectra of fluorescein disodium at various concentrations and temperatures were studied using polyethylene glycol 600 as solvent. From the results obtained, it can be concluded that the geometry of the aggregate changes with the physical state of the solvent: the geometry at low temperatures (polymer in the glass state) involves two molecules of the dye in a sandwich orientation; the geometry in the liquid state involves a linear configuration of the monomers. The exciton splitting of the energy levels of the aggregate in the sandwich orientation can be obtained from the fluorescence spectra as 1180 cm-1. The dependence of the fluorescence spectra on the temperature enables the changes in the geometry of the aggregates and the relaxation temperatures of the polymer chains to be investigated.