Optical absorption and emission spectra of Tb in hexagonal crystals of Na3[Tb(pyridine-2,6-dicarboxylate)3] · NaClO4 · 10H2O

We have measured and analyzed the polarized orthoaxial luminescence and absorption spectra of Tb³⁺ and Eu³⁺ in single crystals of trigonal Na₃[Ln(dpa)₃]·NaClO₄·10H₂O (dpa = 2,6-pyridinedicarboxylate, the dianion of dipicolinic acid). Differential linear polarization (σvs. π) is measured in the orthoaxial luminescence and absorption spectra. A semiempirically derived energy level scheme is developed for the crystal field components of the Tb³⁺ (⁷F_j (J = 0–6), ⁶D₄, ⁶D₃, ⁵G₈, ⁶L₁₀, ⁶D₂) ⁶G₅) and the Eu³⁺ (⁷F_j (J = 0–6), ⁶D_j (J = 0–3) multiplets.