ISC is potentially much faster for TIPS-Tn than TIPS-Pn, which can partly be explained by the smaller difference in energies between S 1 and T 1 . ISC may make a significant contribution to T 1 formation at higher concentrations, or faster rates of SF, than for TIPS-Pn. There are few studied in the literature about ISC in TIPS-Tn. For the very high concentrations of TIPS-Tn solutions studied previously (300 mM), the rate of SF (or excimer formation) would be sufficiently fast to far outcompete ISC. also reported the TA of a 0.51 mM solution of TIPS-Tn in chloroform. They set an upper limit of 6% triplet formation over 3 µs, which they attributed entirely to ISC. Using the rate constants found here, we predict a triplet yield of 12-13% over the singlet lifetime, of which ∼20% is in fact due to SF. More significantly, the higher rate constant of ISC can lead to the overestimation of SF rate constants or yields. In the case of the 8 mM solution studied here, including ISC shifted the SF rate constant from (2.6 ± 0.6) × 10 9 M -1 s -1 to (2.0±0.6)×10 9 M -1 s -1 , and the SF triplet yield from 18-28% to 13-23%. ISC could continue to contribute significantly to T 1 formation up to 35 mM, where ∼5% of triplet formation is predicted to be due to ISC. ) and (5). Also shown are the triplet yields predicted using the upper bound of the ISC rate constant in this study.