Energieübertragung zwischen gleich- und ungleichartigen Molekülen in LösungII. Experimente über Konzentrationsdepolarisation der Fluoreszenz / Energy Transfer Among Like and Unlike Molecules in Solution.II. Study of Concentration Depolarization of Fluorescence

Abstract

Abstract Radiationless energy transfer between like molecules (homotransfer) in thin rigid cellulose acetate films was studied by the concentration depolarization of the photoluminescence. The investigated substances are rhodamine B, 9-methylanthracene and 5-methyl-2-phenylindole. The experimental results have been compared with the “multi-shell model” of a luminescent centre. Good agreement was found with the equation which takes into account the excitation energy remigration. Concentration -depolarization measurements show that the critical distances R1, at which the probability of transfer of the excitation equals that of emission, are dependend on the excited wavelength. This is due to the failure of thermal relaxation of the exciting molecules with their environment.