Analysis of the absorption spectra 4fN+1to 4fN5d-6s of rare-earth ions in the cubic field. II. Eu2+ion in alkali-earth chalcogenides

For pt.I see ibid., vol.12, p.4081 (1979). The excitation spectra of MgS:Eu 2+ phosphors were measured at 300 and 80K. Two distinct bands assigned to the 8 Gamma 4 (t 2g ) and 8 Gamma 3 (e g ) bands appear for lower concentrations of Eu 2+ ions and in addition, two bands assigned to the 8 Gamma 1 (6s) and 6 Gamma 4 (t 2g ) bands are observed for higher concentrations of Eu 2+ ions. The shapes of the absorption spectra 4f 7 to 4f 6 5d-6s of an Eu 2+ ion in MgS are calculated by using the energy matrix for the 4f N 5d-6s configurations and the atomic spectrum data for a free Eu 2+ ion. Comparison between the observed and calculated results confirms the band assignment and leads to the determination of some energy parameters.