A general approach to calculate the individual spectra of species in excited state reactions is presented. Such spectra, which we call species associated spectra, SAS, are recovered from time-resolved emission data sampled at different wavelengths. SAS are presented in this paper for systems that also show ground state heterogeneity. Deconvolutions of single-photon-counting data have been carried out with the technique we call the global-reference method, i.e. global deconvolutions with quenched references, which also is discussed in the paper. Results are presented for global-reference deconvolutions of exponential decays and of fluorescence anisotropy described by anisotropic rotations of heterogeneously emitting systems. Some future projects are also discussed.