Abstract
Optical absorption and emission spectra are reported for single crystals of the cubic elpasolite Cs 2NaSmCl 6. The variable temperature spectra obtained at high resolution are assigned using energies and relative intensities. Transitions from the ground level, 6H 5 2 to cystal fi levels of 6H 7 2 - 15 2 , 6F 1 2 - 11 2 , 4G 5 2 - 9 2 , 4F 3 2 , 5 2 , 4I 9 2 , and 6P 3 2 , 5 2 are located and characterized. Intensity calculations are reported for magnetic dipole allowed transitions. The dominance of vibronic intensity in 6H 5 2 → 6F 1 2 - 9 2 and 6P 3 2 , 5 2 transitions is accounted for qualitatively through the ligand polarization model involving quadrupole metal (Sm 3+)-ligand (Cl −) interaction mechanisms. The E u″( 6H 5 2 )→E′( 6H 1 2 ) E u′( 6F 1 2 ) no-phonon transition is postulated to be pure electric quadrupole allowed. The ground state magnetic moment is determined to be very small from magnetic circular dichroism (MCD) spectra. This study has led to the assignment of nearly all of the crystal field levels in the visible and IR region for Cs 2NaSmCl 6. A total of 27 such levels were identified, 17 from no-phonon transitions and the rest from vibronic transitions. The magnetic dipole intensity calculated using intermediate coupling O h wavefunctions along with a crystal field analysis of the splitting pattern was used in the assignment of the levels. Vibronic bands were observed for all transitions and their vibrational symmetries were tentatively assigned. MCD data were used to determine the magnet moment of the ground state.
Published Version
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