Application of the Eu3+ ion for site symmetry determination

Abstract

A scheme has been developed to determine the site symmetry of rare earth compounds on the basis of the number and polarization of the peaks in the Eu3+ absorption spectrum for the magnetic dipole allowed D-5(1)<--F-7(0) transition and the electric dipole allowed D-5(2)<--F-7(0), 5D4<-- 7F0 and 5L6 <-- 7F0 transitions. The Eu3+ ion is chosen as probing ion because of its non-degenerate ground state 7F0 and the well-separated (2S+1)L(J) multiplets. For the luminescence spectrum, an adapted scheme is presented. In this way it is possible to discriminate between all non-centrosymmetric crystallographic point groups. For rare earth compounds in solutions the scheme has to be adapted, because no polarised spectra can be recorded, only the number of spectral peaks can be counted.