Charge-transfer transitions of transition metal impurities in oxides

Abstract We have made predictions of the energies of optical absorption and emission of transition metals in MgO and CaO. The calculations are for those transitions in which substitutional Mn, Fe, Co or Ni ions change their charge state. Whilst agreement with experiment is good in some cases, it is less good in others, possibly because of doubts about the species and transitions responsible for the observed bands. The results support the conclusion of our previous work (Stoneham and Sangster 1981) that the electron affinity of MgO is negative.