Several interpretations have been previously proposed, for the constitution of the luminescent centres, built with copper and silver impurities in zinc and cadmium sulfides. For each of them, the spectral distribution of the radiative recombination probabilities must be characteristic. So, the authors have recently established that, in this case, the vibro‐electronic and the donor—acceptor theories are not suitable, and that a centre model with a band of excited states would be more convenient to explain the results. Starting from this scheme of recombination, it is shown that it leads to a parallelism between the distribution of the emitted energy and the localization degree of the luminescent processes. The reduction of the sample dimension is a selective way to act on the spectral diversity in the localization of the mechanisms. The spectral changes in the emission probabilities and especially in the intensity which are expected from the evolution of this unusual parameter, must be specific of the model. The observed shifts of the emission spectra and the recorded modifications of the radiative lifetime distribution, give the first proof, directly showing the validity of a model with an excited states band and allows to suggest an explanation of the characteristic shape of the lifetime repartition τ(λ).