Journal of Chemical Physics vol:95 issue:5 pages:3099-3106
It is shown that the sum of the intensities for magnetic dipole transitions between crystal-field components of two free-ion levels in lanthanide spectra is almost independent of the symmetry of the environment. A mean theoretical sum value of 18 x 10(-7) D2, 94 x 10(-7) D2, and 9 x 10(-7) D2 for, respectively, the 5D1 <-- 7F0, 5D0 <-- 7F1, and 5D2 <-- 7F1 dipole strengths has been found. Experimental values of the dipole strength for Eu3+ in different lattices support within reasonable limits the theoretically derived sum rule. We therefore propose to use these magnetic dipole transitions in the Eu3+ spectrum as standards for further Judd-Ofelt parametrization.