Laser diagnostics of complicated organic compounds and complexes by saturation fluorimetry

A fundamentally new approach to fluorescence diagnostics of complicated organic compounds and complexes is proposed. This approach is particularly suited to diagnostics of natural organic complexes. It is based on in vivo and in situ measurements of the parameters that govern the photophysical processes in complexes and which depend on the intermolecular and intramolecular interactions. These parameters include the cross section of absorption of the exciting optical (specifically, laser) radiation, the excitation cross section of the fluorescence-emitting molecules in a complex, the quantum yield of a triplet state formed by intercombination conversion, the rate constant of singlet — singlet annihilation, etc. These parameters are determined from the fluorescence saturation curves, i.e. from the dependences of the number of the fluorescence photons on the exciting photon flux. The capabilities of two algorithms for solving the relevant incorrectly posed inverse problem are considered.