| Popis: |
We present the results of low-temperature absorption spectra of Er3+ in frozen dilute aqueous chloride solutions (0.044 M). In order to interpret these spectra we undertook a reinterpretation of the spectra of ErCl3·6H2O, which are very similar to those of frozen solutions. For the surroundings of the Er3+ ion we used the approximate D4d symmetry recently introduced for interpreting the spectra of rare earths in hexahydrated chloride crystals. We carried out new experiments on the crystal to obtain polarization results. With only three crystal field parameters, and diagonalizing the complete hamiltonian, we obtain for 124 Er3+ levels of the crystal a rms deviation σ = 15.8 cm−1 and crystal field parameters B02 = −531±12, B04 = −1075±30 and B06 = 712±28 cm−1; we obtained for 50 Er3+ levels of the frozen solution σ = 13.2 cm−1 with B02 = −458±38, B04 = −1291±51 and B06 = 694±32 cm−1. These results, along with structural considerations, allow us to conclude that Er3+ is eightfold coordinated in frozen aqueous solutions and has a coordination polyhedron of water oxygens arranged in the shape of a square antiprism with D4d symmetry. |
