EN
The room temperature IR- and Raman spectra of the different M_{3}RE(PO_{4})_{2} (M = K, Rb; RE = La, Eu, Gd) double phosphates were analysed and used to interpret the vibronic side band structure in the photoluminescence spectra. The intraconfigurational 4f-4f electronic transitions in the photoluminescence spectra of the Eu^{3+} doped M_{3}RE(PO_{4})_{2} were analysed in detail. The crystal field fine structure of the ^{5}D_{0} → ^{7}F_{J} (J=0-4) transitions was analysed accounting for the information on the crystal structure. The effect of the temperature as well as the alkali host cation was evaluated. Finally, a preliminary crystal field energy level scheme for the ^{7}F_{J} (J=0-4) ground term was deduced from the analysis of the photo-luminescence as well as IR- and Raman spectra.