SPECTROSCOPY OF COMPLEX DEFECTS IN CRYSTALS OF KMGF3TL+

Characterization of complex defects, formed by ionizing radiations in single crystals of KMgF3:Tl+, is carried out by means of optical spect roscopy and thermoluminescence experiments. Aggregate defects, formed by association of color centers with Tl+ impurity ions, are found to b e responsible for new absorption bands in the 240-260 nm and 280-340 n m regions. Photoluminescence is obtained at 293 nm under excitation in the former and at 435 nm under excitation in the latter. Studies on t he dependencies of emission spectra on dopant concentration, irradiati on dose and temperature allow for the identification of two different kinds of complex centers and for the discovery of an energy transfer p rocesses occurring between them. Spectrally resolved thermoluminescenc e confirms the coexistence in the samples of aggregate centers involvi ng the Tl+ impurity ions with intrinsic defects induced by irradiation in the host crystal lattice, shows evidence of a complex emission dyn amics and gives further support to the attribution of a luminescence a t 240 nm to an intrinsic emission caused by excitation in the fundamen tal absorption of KMgF3.