Nature of the External Heavy‐Atom Effect on Radiative and Nonradiative Singlet–Triplet Transitions

摘要: The nature of the external heavy‐atom effect on radiative and nonradiative singlet–triplet transitions in aromatic hydrocarbons has been investigated experimentally theoretically. From studies perturbed phosphorescence rigid glass mixed‐crystal systems we conclude that:(i) Radiative T1 ↔ S0 are much more susceptible to a than corresponding radiationless transitions.(ii) enhancement is due mixing excited singlet states associated with perturber molecule into triplet state molecule.(iii) important pertuber appear be highly localized heavy atom rather which essentially delocalized [e.g., (π, π*) states].(iv) It does not seem necessary invoke charge‐transfer interactions account for enhancement.