EXCITONIC MECHANISM OF LUMINESCENCE EXCITATION OF RARE-EARTHS AND TRANSITION-METALS IN SOLIDS

We review here some new aspects of the spectroscopic properties of solids doped with transition metal (TM) and rare earth (RE) ions. The main emphasis is given to the evidence of binding of excitons by these ions, and to the impact of such "external excited states" on the efficiency of intra-ion transitions of REs and TMs. It is concluded that TM-, RE-bound excitons are a common feature in solids, and due to the impurity Auger processes play an important role in intra-ion excitation.