Decay kinetics of the triplet luminescence from self-trapped excitons in CdMoO4 and ZnWO4



Decay kinetics of the intrinsic luminescence from the triplet excited state of self-trapped excitons in CdMoO4 and ZnWO4 has been investigated in a wide temperature range between 7 and 300 K. The measurements are carried out under low-density excitation with the fourth harmonics (266 nm) of a Nd:YAG laser. The decay curves show two decay components, fast and slow, at T < 40 K in CdMoO4 and at T < 15 K in ZnWO4. At higher temperatures, the decay curves in both materials are well described by single-exponential functions. A three-level model consisting of two excited states separated by an energy D and a ground state is applied to explain the temperature dependences of fast and slow decay times. From the fit to the experimental data, we obtain D = 3.7 ± 0.5 meV for CdMoO4 and 2.1 ± 0.3 meV for ZnWO4.