OPTICAL-SPECTRA AND ELECTRONIC-STATE STRUCTURE OF -XDYX(DPA)(3)]CENTER-DOT-NACLO4-CENTER-DOT-10H(2)O CRYSTALS( IN HEXAGONAL NA)

Polarized optical absorption and emission measurements are used to loc ate and assign 91 crystal-field energy levels split out of the 4f(9) e lectronic configuration of Dy3+ in hexagonal Na-3[Yb1-xDyx(dpa)(3)]. N aClO4 . 10H(2)O (x = 0.05, 0.2, 1; dpa = dipicolinate dianion = 2,6-py ridinedicarboxylate). The absorption measurements span the 300-1800 nm wavelength range, and the emission measurements span the 470-775 nm w avelength range. The combined absorption and emission measurements pro vide access to the energy-level structures of 35 4f(9) [SL]J multiplet manifolds of Dy3+, which include all multiplet manifolds with baricen ter energies < 33 000 cm(-1) above ground. The site symmetry of the Dy 3+ ions in hexagonal Na-3[Yb1-xDyx(dpa)(3)]. NaClO4 . 10H(2)O is D-3, and all crystal-field levels split out of the 4f(9)(Dy3+) electronic c onfiguration are Kramers doublets with either E' or E '' symmetry in t he D-3 double-rotation group. Among the 187 crystal-field levels predi cted for the 35 multiplet manifolds examined in this study, 91 are bot h located and assigned (with respect to crystal-field symmetry type, E ' or E '', and principal [SL]J multiplet parentage). The 91 assigned l evels are analyzed in terms of a model Hamiltonian that includes consi deration of both isotropic and non-isotropic 4f-electron/crystal-field interactions. A parametrized form of this Hamiltonian is used to perf orm parametric fits of calculated-to-experimental energy-level data, a nd the results obtained from these fits show an rms deviation of 6.3 c m(-1) between calculated and observed energies, The interaction parame ters evaluated from these energy-level data fits are compared to those for Dy3+ in other systems, with particular attention given to Dy(oda) (3)(3-) in Na-3[Dy(oda)(3)]. 2NaClO(4) . 6H(2)O (where oda = oxydiacet ate). The crystal-field energy-level structures of Dy(oda)(3)(3-) and Dy(dpa)(3)(3-) show significant differences, and these differences are discussed in terms of the ligand moieties that are present in the res pective complexes. Among the more than 150 spectral features observed and assigned in the unpolarized axial absorption spectra of Na-3[Dy(dp a)(3)]. NaClO4 . 10H(2)O, 46 are sufficiently well-resolved to permit quantitative determinations of transition line strengths, and these li ne strengths are reported and discussed.