LUMINESCENCE OF A SELF-TRAPPED EXCITON IN GEO2 CRYSTAL

The self-trapped exciton (STE) is discovered in the GeO2 Crystal. A PL band at 2.5 eV with a strong Stokes shift is excited only in the fundamental absorption range of GeO2 crystal with the quantum yield about 0.4 and the decay time constant 800 +/- 5 mus at 80 K. The PL thermal quenching occurs at 200 K with the energy about 0.25 eV and the frequency factor 10(7). At 4.5 K the PL decay kinetics splits into two components with time constants 270 mus and 8000 mus, which can be due to a triplet state split in the zero magnetic field. The STE in GeO2 is very similar to a STE in SiO2.