triplet-triplet transitions

https://doi.org/10.1351/goldbook.T06507
Electronic transitions in which both the initial and final states are triplet states.
Source:
PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2282 (https://doi.org/10.1351/pac199668122223)