QUANTUM UP-CONVERSION OF TM3-HO3+ ION-PAIRS IN CSCDBR3( AND TM3+)

In CsCdBr3 the trivalent rare-earth (RE) ions substitute the divalent Cd ions. For reasons of charge compensation and the quasilinear struct ure of the lattice, only two types of ion pairs are found predominantl y, the weakly coupled symmetric pair RE(3+)-Cd vacancy-RE(3+) and the strongly coupled asymmetric pair RE(3+)-RE(3+)-Cd vacancy. Only the la tter one showed up-conversion, which was studied for a Tm3+ crystal do ped with small impurities of Ho3+. The results are compared with those for Pr3+. The results show that the fluorescence dynamics cannot be d escribed by ion-ion cross relaxation but need the inclusion of electro nic host lattice excitations.