Absorption, monitoring triplet state population

We should keep in mind that the population of the l (triplet) levels isoenergetic with the initially excited j> state may be also monitored, either by transient absorption or by resonant emmision. In the cases... 

Since in most real experiments the population of the radiative states is monitored by the intensity of the (spectrally unresolved) fluorescence (emitted from the s > and u > levels) we are essentially interested in the overall population p s+Pun- Similarly the overall population of the optically nonactive levels p + p (which may be monitored by transient absorption or by emission within the triplet manifold) is of interest. 

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