Abstract of Publication No. 273
D. Reinen, W. Rauw, U.
Kesper, M. Atanasov, H U. Güdel, M. Hazenkamp and U. Oetliker
The spectroscopic properties (absorption, luminescence, EPR) of
d2-configurated cations (Fe(VI), Mn(V), Cr(IV)) doped into the
tetrahedral sites of a great variety of oxidic solids are reviewed and
supplemented by new results. Angular overlap model calculations on the basis of
the host site geometry, utilising a modified ligand field theory with different
Racah parameters for e and t2 orbitals, have been performed, which
nicely fit the experimental data. In particular, they give evidence, that - in
the case of Cr(IV) - the E1 State is usually positioned well above
the luminescing triplet state, in agreement with the experiment. Further, the
calculations allow a characterization of the transition-metal-oxygen bond. It is
finally shown, that the doping cation does not necessarily adopt the host site
geometry; geometric criteria are given.