Time-resolved luminescence spectra in colorless anatase TiO2 single crystal

Time-resolved luminescence was measured on a colorless anatase single crystal under pulsed-laser excitation. The time evolution of luminescence is composed of fast and slow components with time constants of 10−6 and 10−5 s, respectively. The fast component corresponds to a direct formation of STE. Some traps near the conduction band give a retardation effect on the slow component. The traps are occupied by conduction electrons at low temperatures and the trapped electron can be excited thermally at temperatures higher than 100 K. They compete with non-radiative recombination process. A possible model for the relaxation process is proposed.