POLARIZED OPTICAL-SPECTRA, TRANSITION LINE STRENGTHS, AND THE ELECTRONIC ENERGY-LEVEL STRUCTURE OF EU(DPA)(3)(3-) COMPLEXES IN SINGLE-CRYSTALS OF HEXAGONAL U0.05(DPA)(3)]CENTER-DOT-NACLO4-CENTER-DOT-10H(2)O

Polarized optical absorption and emission measurements are used to loc ate and assign 52 crystal-field energy levels split out of the 4f(6) e lectronic configuration of EU(3+) in single crystals of Na-3[Yb0.95Eu0 .05(dpa)(3)]. NaClO4 . 10H(2)O (where dpa drop dipicolinate dianion dr op 2,6-pyridinedicarboxylate). In these crystals, each Eu3+ is coordin ated to three dipicolinate (dpa) ligands, and the tris-terdentate Eu(d pa)(3)(3-) chelate structures have trigonal-dihedral (D-3) symmetry. T he combined optical absorption and emission measurements provide acces s to the energy-level structures of 27 different 4f(6)[SL]J multiplet manifolds of Eu3+, and 21 of these multiplet manifolds are represented among the 52 crystal-field levels that are characterized with respect to both location (energy) and symmetry properties. The energy-level d ata obtained from experiment are analyzed in terms of a model Hamilton ian that includes consideration of both isotropic and nonisotropic 4f- electron/crystal-field interactions. A parametrized form of this Hamil tonian is used to perform parametric fits of calculated-to-expenimenta l energy-level data, and the results obtained from these data fits sho w a root mean square (rms) deviation of 9.8 cm(-1) between calculated and observed energies. The Hamiltonian parameters evaluated from the e nergy-level analyses provide information about both the anisotropies a nd the overall strength of the 4f-electron/crystal-field interactions that contribute to the energy-level structure of Eu(dpa)(3)(3-) comple xes. In addition to energy-revel data, the absorption measurements per formed in this study permit the quantitative determination of relative optical line strengths for 22 different Stark-level-to-Stark-level tr ansitions observed in the low-temperature axial absorption spectra of Eu(dpa)(3)(3-) in Na-3[Yb0.95Eu0.05(dpa)(3)]. NaClO4 . 10H(2)O.