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 ⁶H_5/2 (ground) multiplet and for emissive transitions originating from the ⁴G_5/2 (excited) multiplet.