Key points are not available for this paper at this time.
In two possible symmetry sites exist for the Eu+3 ions, namely S6 and C2. The emission spectrum is primarily due to ions but two additional lines are reported corresponding to emissions. The lines were identified by their long lifetime relative to the C2 emission and represent the Stark splitting of the transition. This is a pure magnetic dipole transition in S6 symmetry and consequently has a low oscillator strength. The absorption transition due to has also been identified. Similar results have been found for the low temperature form of , which is isostructural with .
Forest et al. (Wed,) studied this question.