Light absorption and photoluminescence of Eu3+ ions in CaF2 crystals

From optical transmittance and photoluminescence measurements of natural crystals CaF2:Eu was established the correlation between energy states diagram of Eu3+ ion and the structure of these bands. Photon absorption in this material occurs at electronic transitions from the 7F0 level on the G, D, L configuration levels of Eu3+ ion. Because 7F1 level population is much smaller than the 7F0 fundamental level population, the photon absorption intensity which involving 7F1 level is not evident in absorption spectra at room temperature. CaF2:Eu3+ crystal photoluminescence is determined by electron radiative transitions from 5D0 level to the low energy levels 7F0, 7F2 and, perhaps, 7F3. (authors)