Site-selective spectroscopy in Eu: lanthanum magnesium aluminate

Pulsed resonance emission spectra for La_1-xEu_xMgAl₁₁O₁₉ are reported under excitation into the non-degenerate ⁵D₀ « ⁷F₀ transition of Eu³⁺ at 77 K. Emission spectra recorded under continuous-wave excitation into the same transition at liquid helium temperature were also examined. These results show clear evidence for the existence of only two distinct substitutional site distributions for Eu³⁺, with their ⁵D₀ « ⁷F₀ transitions between 577 and 579 nm. The suggestion of a third site distribution ca. 576 nm is also reported. Discrepancies concerning the number of Eu³⁺ substitutional sites and the positions of their corresponding ⁵D₀ å ⁷F₀ peaks reported in other studies are addressed in the light of our results.