Optical spectra and crystal-field analyses of samarium in the centrosymmetric hexakis(antipyrine)samarium(III) tri-iodide and tri-perchlorate systems

Abstract

Optical absorption and emission measurements are reported for single crystals of Sm(AP)6I3 and Sm(AP)6(ClO4)3 (where AP denotes an antipyrine ligand molecule). Crystal-field energy levels split out of the 4f 5 electronic configuration of Sm3+ are located and assigned from the locations and polarizations of magnetic-dipole origin (no-phonon) lines observed in the optical spectra. The energy levels are analyzed in terms of a parametric hamiltonian that assumes D 3d crystal-field symmetry at the Sm3+ sites. Crystal-field interaction parameters obtained from calculated-versus-experimental energy level fits are reported and compared for the Sm(AP)6I3 and Sm(AP)6(ClO4)3 systems. Good data fits are obtained for both systems, and the rank-two and rank-four crystalfield parameters are reasonably well-determined by these fits. The rank-six parameters are less well-determined. The values determined for the rank-four crystal-field parameters are essentially identical for the tri-iodide and triperchlorate systems; however, the magnitude of the rank-two parameter for Sm(AP)6I3 is twice that for Sm(AP)6(ClO4)3. Magnetic-dipole line strengths are calculated for absorptive transitions originating from crystal-field levels of the 6H5/2 (ground) multiplet and for emissive transitions originating from the 4G5/2 (excited) multiplet.