Magnetic dipole transitions as standards for Judd–Ofelt parametrization in lanthanide spectra

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 18×10−7𝒟2, 94×10−7𝒟2, and 9×10−7𝒟2 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.