If we add in an ISC rate constant of 8.50 × 10 6 s -1 (time constant of 118 ns) we reach a total T 1 concentration (from ISC and SF) of 1.6 × 10 -8 M at 8 ns, which matches the noise limit. Hence the ISC rate constant of TIPS-Tn in toluene should be smaller than 8.50 × 10 6 s -1 , or the time constant should be longer than 118 ns. This rate constant corresponds to an ISC quantum yield of 11% at 0.05 mM. Figure shows the experimental and modeled TA data around the triplet peak maximum at 508 nm. The modeled data include artificial noise from a Gaussian distribution with the same standard deviation as the experimental TA data. On close inspection, the experimental TA data around 508 nm does in fact show some shape change over 8 ns, consistent with the trend in the modeled data due to an increasing triplet population. The magnitude of this increase in the experimental data over 8 ns is about 2.3% of the GSB magnitude, which is approximately equivalent to 0.041 mOD. An upper bound of 0.049 mOD T 1 absorption is therefore a reasonable estimate.