Strickler Berg relation

The second parameter Moi also scales <5 of dipolar compounds and can be evaluated from the absorption spectrum using the Strickler-Berg treatment [338]. Reorganization of this relation results in Eq. (26) [338-340], showing the inverse proportionality between (M01)2 and excitation energy Em, but a direct relation exists between (Mqi)2 and the integral over the absorption band. 

As we noted in Sect. 5.1, the Einstein relationship between absorption and fluorescence (Eq. 5.12) assumes that absorption and emission occur at a single frequency, which is not the case for molecules in solution. However, the overall rate of fluorescence by a molecule with broad absorption and emission bands can be related to the integrated absorption strength by expressions that were developed by Lewis and Kasha [18], Forster [19], Strickler and Berg [20], Birks and Dyson [16] and Ross [21]. 

This relation is only strictly applicable to two-level systems, such as atomic systems, where the transitions have sharp lines and in a medium of refractive index =1. The electric dipole radiation dominates the mechanism of radiative decay in molecular systems. For molecular systems in solution, Strickler and Berg proposed a modified equation that gives good results for the radiative rate [7]... 

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