Fluorescence Spectrum and the Energy Levels of the Sm2+ Ion

Abstract

Sm²⁺ which occurs as impurity in very small concentrations in LaCl₃ has a very distinctive fluorescence spectrum which resembles in all details that of Eu³⁺. Excitation is through the very strong continuous absorption to 4f⁵5d in the visible. The energy is transferred to the stable states ⁵D₀ and ⁵D₁ of the 4f⁶ configuration separated by 1330 cm^—1 from which emission to the components of the ground multiplet ⁷F is observed. The fact that in all cases the spatial degeneracy is completely removed shows that the field around the Sm²⁺ ion has low symmetry even though the La³⁺ ion which it replaces is in an hexagonal field.