Truncation Effects on Crystal Field Calculations for The 4f⁶(Eu³⁺) Configuration in Solids

Abstract

Trivalent europium is an important rare earth element which has many applications in luminescent materials. It is also widely used as an optical structural probe for solid state studies because of its simple sequence of energy levels and well established set of selection rules for transitions. The fluorescence can also be excited easily in the upper ⁵D₀ level with the relatively new Rhodamin 6G dye laser technology. Despite the very extended use of europium, crystal field problems are usually treated for this ion on the limited basis of the 49|SLJM_J> kets in the ⁷F_J multiplet. This of course is sufficient to determine the crystal field parameters, but it is not precise enough when wave vectors are needed to parametrize some important properties such as intensities of fluorescence lines. Then, one should correct the vector composition in a way which may be arbitrary (1).