OPTICAL SPECTROSCOPY OF EU3+ DOPED ZINC BORATE GLASSES

Zinc borate binary glasses of composition 4ZnO.3B2O3 undoped and doped with 0.5% mol of Eu3+ were prepared from the melt giving rise to samp les of excellent optical quality. In the present work we use the spect roscopic properties of the Eu3+ to obtain information about the struct ural and dynamic features of our system. Different optical techniques such as site selection, excitation spectroscopy and lifetime measureme nts as well as Raman spectroscopy were used to study the local environ ment of the Eu3+ ion in these glasses. No energy transfer is observed at our concentration and moreover non-radiative relaxation from the ex cited 5D0 state to the F-7(J) manifold is not important. A broad distr ibution of slightly different environments of the Eu3+ ion is reflecte d in the trend of the Stark splittings of the F-7(J) state and in the crystal field parameters for the individual sites as a function of the excitation wavelength. Phonon sidebands are observed in the excitatio n and luminescence spectra of the Eu3+ impurity. We make an attempt to assign these sidebands to coupling of the vibrational modes of the st ructural units containing the Eu3+ ion. The strength of the electron-p honon coupling is evaluated and compared with the result obtained for related systems.