Time-resolved luminescence spectra in colorless anatase TiO2 single crystal

Abstract

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 À6 and 10 À5 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. r

EPR of anatase titanium dioxide under uv light irradiation

“…1) reveals the presence of two types of spintrapping levels which are effectively in relaxation process from the photo-excited state. The appearance of the sextuplets at 100 K suggests that the dominant relaxation process will change at 100 K. We re- Magnetic Field (Gauss) ported a comparable phenomenon in a study on time resolved photoluminescence [8]. Temperature dependence of life time of luminescence has a maximum at about 100 K. The extraordinarily large static dielectric constant of titanium dioxide (~170) [9] suggests that these spin-trapping levels are shallow.…”

On the mechanism of enhanced photocatalytic activity of composite TiO2/carbon nanofilms

“…The decay curve comprises fast and slow time components. The fast time constant is associated with direct formation of STE from free electrons and holes and the slow time constant is related to indirect formation of STE due to phonon assisted emission from traps [36,37]. For a rough estimation of the influence of the carbon film (see Fig.…”

Influence of oxygen vacancies on optical properties of anatase TiO2 thin films

“…The photocatalytic activity of anatase TiO 2 is affected by defect states (oxygen vacancies) in the crystal due to the defect states' influence on the relaxation process of photo-excited carriers [1]. To understand the relationship between the relaxation process and defect states, the timeresolved luminescence measurement is effective.…”