Journal of physics-condensed matter vol:8 issue:9 pages:1267-1279
The polarized absorption spectra of europium bromate enneahydrate Eu(BrO3)3.9H2O have been recorded at ambient temperature and at 77 K between 16 500 and 36 000 cm(-1). The site symmetry is approximated by a D3h symmetry. 63 crystal field levels have been assigned. The energy level scheme is parametrized in terms of 20 free ion parameters and four crystal field parameters. The crystal field parameters are B20 = 205 cm(-1), B40 = -279 cm(-1), B60 = -557 cm(-1) and B66 = -872 cm(-1). Because of the weak crystal field felt by the Eu3+ ion, J-mixing is not very important in the bromate matrix. A consequence is that most of the observed induced electric dipole transitions starting from the 7F0 level obey the DeltaJ = 2, 4, 6 selection rules of the Judd-Ofelt theory. Comparison with other Eu3+ systems enables us to conclude that a tricapped trigonal prism as a coordination polyhedron (C.N. = 9) results in weak crystal fields, regardless of the chemical nature of the ligands.