Phonon sidebands and vibrational properties of Eu3+ doped lead germanate glasses

The phonon sideband spectra of the F-7(0) --> D-5(0) and F-7(0) --> D-5(2) electronic transitions of Eu3+ are reported and assigned on the basis of the vibrational Raman spectra for a series of lead germanate glasses of molar compositions (x-1)PbO . (100-x)GeO2 . 1Eu(2)O(3) with x = 30, 40 and 50 mol%. The samples were prepared by melting the appropriate amount of the oxides at 1100 degrees C for 2 h, and quenching and annealing at temperatures from 320 to 380 degrees C for 15 h. The electron-phonon coupling strength of the Ge-O stretching modes coupled to the F-7(0) --> D-5(2) transition was evaluated by determining the ratio of the intensity of the phonon sideband to the intensity of the zero phonon line. With increasing lead content, the coupling strength appears to increase (within the experimental uncertainties) from 0.010 (x = 30 mol%) to 0.012 (x = 50 mol%). (C) 1997 Elsevier Science B.V.