A series of papers by Grieco et al. also refer to ISC in TIPS-Pn solutions. They reported seeing a small population of triplets on a microsecond timescale in a 1 mM solution in CCl 4 . They claimed that the solution was dilute, and that SF must not occur, and thus attributed the triplet formation to ISC. While not as concentrated as the solutions that other studies used to measure SF, 1 mM is still an order of magnitude higher than the dilute solution studied by Walker et al. in which triplets were not observed. If we take k SF measured by Dvořák et al. (4×10 9 M -1 s -1 ), and the upper bound of k ISC measured here, we would expect a triplet yield of 19.2% at 100 ns. 30% of this triplet production comes from ISC, and 70% from SF (Table ). We have used the rate constant from Dvořák et al. rather than the rate constant measured here as the viscosity, and therefore rate of diffusion in CCl 4 is closer to that in chloroform than that in toluene. Grieco et al. did not quantify the amount of triplets observed, so we cannot comment on whether the magnitude of the ISC and SF rates are consistent with their data, but it seems likely that any triplets that were observed were more likely due to SF than to ISC.