ABSTRACT

Here τi is the intrinsic lifetime of the excitation residing on molecule i (i.e. the fluorescence lifetime one would observe for the isolated molecule), wij is the pairwise energy transfer rate and Fi is the rate of excitation of the molecule i by the external source (the photon flux multiplied by the absorption cross section). The master equation system (C3.4.4) allows one to calculate the complete dynamics of energy migration between all molecules in an ensemble, but the computation can become quite complicated if the number of molecules is large. Moreover, it is commonly the case that the ensemble contains molecules of two, three or more spectral types, and experimentally it is practically impossible to distinguish the contributions of individual molecules from each spectral pool.