Simple way to test the validity of 2S+1LJ barycenters of rare earth ions (e.g. 4f2, 4f3 and 4f6 configurations)

New zinc borate glasses of composition 4PbO·2ZnO·5B2O3· and 2PbO·4ZnO·5B2O3 doped with Pr3+, Nd3+, Eu3+, Dy3+, Ho3+ and Er3+ were prepared. Absorption and luminescence spectra were measured and the Judd-Ofelt parameters were calculated. The spectroscopic behaviour appears to be strongly influenced by the presence of the highly polarizable Pb2+ ion. The values of stimulated emission cross sections for selected laser transition appear to be relatively high, suggesting that these materials can be considered as interesting candidates for optical applications.