Emission from an excited triplet state during ECL

The application of Marcus theory of electron transfer reactions for the case of radical ion chemiluminescence of 9,10-diphenylanthracene (DPA) gives a high rate constant value (10⁹–10¹⁰ M^?1 s^?1) for the formation of the second triplet state (T₂). It is suggested that the near infrared emission observed during electrochemiluminescence of DPA is due to T₂ → T₁ fluorescence based on the high yield of T₂ (≈0.7) in the electron transfer reaction.