Chemiluminescence as the energy transfer effect in the system Eu(III)–thenoyltrifluoroacetone–H2O2–NaOH

Chemiluminescence (CL) of the water–ethanol solutions containing hydrogen peroxide, sodium hydroxide and europium(III) complex with thenoyltrifluoroacetone (TTA) was studied. It has been established that the introduction of europium(III) chelate into the system H2O2–NaOH caused an increase in the CL intensity and significantly extended its duration (up to a few hours). The dominant band in the emission spectrum has been the one at λ∼600 nm, which means that Eu(III) ions are the only emitters in the system H2O2–NaOH–europium(III) chelate. The study revealed a strong connection between the CL intensity and the concentrations of europium(III) chelate and hydrogen peroxide. These relations and a strong influence of the competitive ligand (aminopolycarboxylic acid) suggest that the excitation of Eu(III) ions takes place in the complex through the mediation of TTA ligand. A mechanism of the processes taking place in the system has been proposed, taking into account the process of energy transfer from the products of decomposition of hydrogen peroxide to the Eu(III) ions in the complex with TTA.