Fine Structure in the Optical Spectra of Divalent Europium in the Alkaline Earth Sulfates

Abstract

Fine structure has been observed in the fluorescence and excitation spectra of Eu+2 in and in the fluorescence spectrum of Eu+2 in . The fine structure in the fluorescence of Eu+2 in is identified as a zero phonon line with many sharp phonon replicas. The fine structure in its excitation spectrum is due to the closely spaced energy levels in the excited state produced by a strong exchange interaction splitting of the 4f65d states. The fine structure in the fluorescence of Eu+2 in is due to the normal splitting of the 4f7 excited state and the dominance of 4f7 → 4f7 transitions.