Spectroscopy of divalent samarium in LiBaF 3

Abstract

The luminescence of Sm 2+ in LiBaF 3 is investigated. The Sm 2+ ion occupies a centrosymmetric site in this host lattice. The magnetic dipole (MD) and vibrationally induced electric dipole transition probabilities for eight different 5 D J → 7 F J transitions are reported. The ( L + 2 S) 2 matrix elements for the MD allowed transitions are determined and compared with theoretical values for the same transitions on the isoelectronic Eu 3+ ion. The transition probabilities A VIB for the vibrationally induced electric dipole transitions are used to test theoretical models that predict A VIB to be proportional to ( U (2)) 2. The dependence of A VIB on ( U (2)) 2 is in fair agreement with theory. However, also transitions characterized by U (2) = 0 show vibronic side bands, albeit on average three times weaker than for the U (2) ≠ 0 transitions. To explain these vibronics we propose to include higher order perturbations in the theory on vibrationally induced electric dipole transitions.