Polarized absorption spectra of Eu(BrO3)(3)center dot 9H(2)O

The polarized absorption spectra of europium bromate enneahydrate Eu(BrO3)(3) . 9H(2)O 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 D-3h 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 8(0)(2) = 205 cm(-1), B-0(4) = -279 cm(-1), B-0(6) = -557 cm(-1) and B-6(6) = -872 cm(-1). Because of the weak crystal field felt by the EU(3+) 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 F-7(0) level obey the \Delta J\ = 2, 4, 6 selection rules of the Judd-Ofelt theory. Comparison with other EU(3+) 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.