4f yields 4f TRANSITIONS AND CHARGE TRANSFER SPECTRA OF Eu^{3 +} , 4f yields 5d SPECTRA OF Tb^{3 +} , AND ¹S₀ yields ³P₁ SPECTRA OF Pb^{2 +} IN ALKALINE EARTH METAPHOSPHATE GLASSES.

Oscillator strengths and quantum efficiencies of Eu**3** plus in MO-P//2O//5 glasses were measured (M equals Mg, Ca, Sr, or Ba). The ratios of fluorescence from **5D//1 and **5D//0 levels of Eu**3** plus to the **7F multiplet is explained by interaction with the vibrational modes of the various glasses. From the fact that charge transfer spectra of Eu**3** plus , 4f yields 5d spectra of Tb**3** plus , and **1S//0 yields **3P//1 of Pb**2** plus did not show any difference in the wave number of maximum absorption when the network modifier was interchanged, it was concluded that the symmetrical part of the crystal field of the glass is independent of the network modifier. A standard for fluorescence quantum efficiency is proposed.