Quenching of heterogeneously emitting systems

When a system contains a fluorophore in different environments (e.g. a fluo-rophore embedded in microheterogeneous materials such as sol-gel matrices, polymers, etc.) or more than one fluorophore (e.g. different tryptophanyl residues of a protein), the preceding relations must be modified. If dynamic quenching is predominant, the Stem-Volmer relation should be rewritten as 

---