@A00036@ which takes place with the transition from the lowest @T06503@ of the molecule to higher triplet states (T → \(T_{n}\)) thus leading to the triplet-triplet @A00043@.
Source: PAC, 1984, 56, 231. (Nomenclature, symbols, units and their usage in spectrochemical analysis-Part VI: molecular luminescence spectroscopy) on page 234 [Terms] [Paper]