Absorption and Fluorescence of Sm(III) Complexes with some Terdentate Ligands

Absorption and Fluorescence of Sm(III) Complexes with some Terdentate Ligands

Spectroscopic measurements and theoretical calculations are performed for the four 1 : 3 Sm(III) : ligand solutions. The ligands included in this study are oxidiacetate, iminodiacetate, methyliminodiacetate and dipicolinate. The oscillator strengths for the $4f{\to}4f$ multiplet-to-multiplet transitions are empirically determined from the absorption spectra. The intensity parameters ${\Omega}_{\lambda}\;({\lambda}=2,\;4,\;6)$ of $Sm^{3+}$(aquo) and ${SmL_3}^{3-}$ complexes are also evaluated by applying the Judd-Ofelt theorem to the observed oscillator strengths. The values of the intensity parameters are compared and discussed in term of structural properties of the complexes. In addition, the fluorescence spectra are reported for the Sm(III) complex systems under mild alkaline condition. The excitation from the $^6H_{5/2}$ ground state to any excited states lying above the emitting energy level $(^4G_{5/2})$ produces four fluorescence bands, following nonradiative transitions from a certain excited state to the $^4G_{5/2}$ state. The ratios of oscillator strengths of ${SmL_3}^{3-}$ complexes to that of $Sm^{3+}$(aquo) are also evaluated from the fluorescence spectra and compared to the results obtained from the absorption bands.