Fluorescence line narrowing spectroscopy of Eu3+ in a niobium tellurite glass

The relationship between optical properties and local structure has been studied in a niobium tellurite glass of molar composition 4.0Nb(2)O(5)-87.0TeO(2)-8.5Al(2)O(3)-0.5Eu(2)O(3) using both broadband and laser-induced fluorescence line narrowing techniques. From the broad band excitation and emission spectra information about the local symmetry and the main lanthanide-ligand vibrational modes of the Eu3+ ions in this matrix was obtained. Under laser selective excitation in the F-7(0)-->D-5(0) inhomogeneous band the site-dependent luminescence of the Eu3+ ions allow us to analyze the distribution of local environments for the lanthanide ion in the nobium tellurite glass. Moreover, the energies of the Stark components of the F-7(1) and F-7(2) multiplets were obtained as a function of the excitation energy and a crystal field analysis was carried out assuming a C-2v site symmetry. From the calculated crystal field parameters B-kq the ratios B-22/B-20 and B-44/B-40 for each excitation energy were obtained and compared with the values calculated using the geometric model proposed by Brecher and Riseberg.