In the case of a rapid photochemical process, a new theoretical result relating time-resolved emission spectroscopy data to three physical parameters of the chemical system has been recently proposed. This previous work, based on a simulation study, is experimentally evidenced in the present paper, using europium/acetate as a model system. The comparison of the emission spectra obtained upon direct excitation of europium (394 nm) and by use of the “antenna effect” (266 nm) evidences the occurring of a back-dissociation of excited europium complexes to form solvated excited free europium ions.