ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Energies and intensities of 114, 101, and 76 f–f absorption transitions of Er3+ are determined by high-resolution spectroscopy in the closely related host lattices Cs3Lu2Cl9, Cs3Lu2Br9, and Cs3Y2I9, respectively. The observed trends in the energy-level structure reflect the increasing covalency and the length of the Er3+–X− bond. The decreasing Coulomb repulsion of the 4f electrons, spin–orbit coupling, and crystal-field potential reduces the energy splittings of the SL, SLJ, and SLJMJ states by 0.5%, 0.5%, and 25%, respectively, along the series Cl–Br–I. Energy-level calculations that include crystal-field and correlation crystal-field terms in the effective Hamiltonian, reproduce most of the experimentally found trends. Root-mean-square standard deviations of 18.0, 19.2, and 21.9 cm−1 are reached in least-squares fits to the experimental crystal-field energies. The f–f transition intensities increase along the series Cl–Br–I as a result of the decreasing energy of the f–d bands. In the iodide compound, where the first f–d bands are as low as 30 000 cm−1, this influence is especially pronounced for the f–f absorptions at higher energy. The quality of the wavefunctions obtained in the energy-level calculations is not sufficient to reliably calculate the relative absorption intensities of individual crystal-field components within a given multiplet transition. This deficiency is ascribed to small deviations of the actual coordination geometry of Er3+ from the C3v point group symmetry that was assumed in the calculation. Intensities are analyzed on the level of multiplet-to-multiplet transitions using the Judd–Ofelt formalism. © 1999 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.479139
Permalink
