Optical absorption and laser excited fluorescence spectra of LaF<SUB>3</SUB>:Eu<SUP>3+</SUP>

The optical absorption spectrum of LaF3:Eu3+ single crystal at liquid nitrogen temperature (LNT) showed two groups of lines around 5240 and 4640 &#197; which are attributed to the Stark levels associated with the 5D1 and 5D2 of Eu3+. The fluorescence spectrum of this system at LNT excited with the 4580 and 5145 &#197; lines of the Ar+ laser revealed 12 groups of lines originating in the Stark components of 5D0,1,2 and terminating in those of the 7F0,1,2,3,4,5 levels. Most of the Stark components of the energy levels of the LaF3:Eu3+ system lying below 20000 cm&#8722;1 could be determined from these spectra. The polarizations of the lines indicate a C2v site symmetry, and all the observed Stark components are categorized under the symmetry species of this group