Optical transitions of Eu3+ ions in EuCl3 solutions

The optical absorption spectra of EuCl₃ in aqueous and acidic solutions were measured in the visible anduv regions of the spectrum. The concentration as well as the temperature of the solutions were varied to establish an accurate free-ion energy level scheme of Eu³⁺. The energy levels were assigned on the basis of a correlation between the calculated and the experimentally observed transition energies and associated band intensities.