OPTICAL-ABSORPTION OF TL+ IONS IN KMGF3 CRYSTALS

Absorption spectra of Tl+-doped KMgF3 single crystals have been measur ed at various temperatures between 9 and 300 K in the V.u.v. region. T hree main bands are found, and they are labelled A, B, C in order of i ncreasing energy because of their close similarities to those of Tl+ i ons in alkali halides. The most striking novelty in KMgF3:Tl+ is given by the clearly resolved structures of the A and C bands, which both e xhibit three components at all temperatures. These structures are rela ted to the Jahn-Teller splitting, due to the interaction of the impuri ty ion with non-cubic lattice vibrations, and to a static distortion o f the host lattice.