Optical absorption and emission spectra of Cs2NaHoCl6

Abstract

Optical absorption and emission spectra are reported for the cubic Cs2NaHoCl6 elpasolite system. Detailed energy and intensity analyses of the high-resolution, variable-temperature spectra allow characterization of the crystal field energy level structure associated with eleven of the Ho3+ term levels. The term levels included in these analyses are 5I8, 5I7, 5F5, 5F4, 5S2, 5F3, 5F2, 3K8, 5G6, 5G5, and 3K7. Intensity calculations are reported for both the pure magnetic dipole transitions and the vibronically induced electric dipole transitions associated with the ν3(t1u), ν4(t1u), and ν6(t2u) vibrational modes of the octahedral (Oh) HoCl63− chromophoric moiety of the Cs2NaHoCl6 system. The electric dipole intensity model used in these calculations includes contributions from both the static-coupling and dynamic-coupling Ho3+-ligand interaction mechanisms. Excellent agreement between observed and calculated intensities is found, and the theoretically calculated intensity results proved crucial to our detailed analysis and assignment of the observed spectra.