Energy levels and hypersensitivity of samarium(III) in the elpasoliteCs2NaSmCl6

Abstract

Electronic absorption spectra ofneat Cs2NaSmCl6 between 300 and 10 K are reported for the spectral region between 900 and40 000 cm−1. Interpretation of the intricate vibronic structure enables 91 conclusiveand 45 tentative Kramers doublet and quartet energy levels of the4f5 ionSm3+ in this system to be assigned. Configuration interaction assisted crystalfield calculations employing the diagonalization of the combined4f5 and 4f46p1 matrices fit the energy levels better than the conventional4f5 crystal fieldcalculation. The 4f5 calculation is more accurate, however, than for thePr3+ and Nd3+ elpasolite systems, showing the greater importance of intra- rather thaninter-configuration interaction for the more complex electronic structure ofSm3+. The experimental dataset generally shows agreement with that from two-photon excitationspectroscopy and the differences are highlighted. The intensity of structure at and near thezero phonon line of the hypersensitive infrared absorption transition increases relative to the intensity of the vibronic sideband whenz isincreased in Cs2NaSm(Cl1−zBrz)6. This is attributed to the introduction of electric dipole transition intensityinto the pure electronic transition by lowering the site-symmetry ofSmCl63−, or by thepresence of SmCl5Br3−.