Triplet population

Hence the steady-state population of triplets should increase under heavy-atom perturbation. However, this conclusion is valid only if unimolecular decay is the main route leading to triplet state depopulation. If bimolecular triplet quenching as shown below is more important than unimolecular decay by several orders of magnitude, kd could be increased as much or more than klte without decreasing the steady state triplet population<136) ... 

In both cases discussed above determinations should be made at several different flash intensities and the results extrapolated to 7 = 0 to eliminate errors due to bimolecular triplet processes arising from the high triplet populations. 

Triplet quantum yields for eosin and some other dyes have been determinded by Soep et al. The system to be studied is exposed to a dye laser pulse (with tunable wavelength) and the transient absorb-tion changes in the system due to triplet population are recorded with the light from a dc xenon lamp. 

Unfortunately there are no experimental results which could be compared with these theoretical curves. All experiments reported in the literature are either made with cyanine dyes showing some excited state absorption or with phthalocyanine dyes which have an extremely high intersystem crossing rate so that triplet populations cannot be neglected. 

For the general case, when neither the steady state approximation nor approximations regarding relaxation rates are valid, one has to use computer solutions of a set of rate equations, analogous to those above, including the triplet population. 

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