For TIPS-Tn, SF begins to produce the same amount of triplet excitons as the upper limit of ISC at a concentration of 2.1 mM. At 8 mM, this rate of ISC would account for 22% of triplets formed by 8 ns. So as with TIPS-Pn, the assumption of negligible ISC when fitting the bimolecular SF rate constant is potentially invalid. Refitting the deconvoluted concentrations of the 8 mM TA with an ISC rate constant of 8.50 × 10 6 s -1 , gives a bimolecular SF rate constant of (2.0 ± 0.6) × 10 9 M -1 s -1 (supplementary material Sec. S4. 3.3, Fig. 6(d)). Using this adjusted rate at 0.05 mM results in 2.7×10 -10 M of triplets formed due to SF, which is still substantially lower than the limit of detection, so an upper bound of 118 ns for ISC is still valid. As with TIPS-Pn, the 8 mM TIPS-Tn S 1 population decays faster and fits slightly better than without ISC. Given that 8.50 × 10 6 s -1 is an upper bound on the ISC rate constant, the range of bimolecular SF rate constants can now be considered to be between 1.4 × 10 9 M -1 s -1 (lower bound of T 1 concentration, upper bound of ISC) to 3.2×10 9 M -1 s -1 (upper bound of T 1 concentration, no ISC), or (2.3±0.9)×10 9 M -1 s -1 .