Under 325nm laser light irradiation at room temperature in O gas, the photoluminescence intensity of pristine anatase TiO2 decreased considerably and then recovered reversibly under the same laser light irradiation at room temperature in vacuum. This furnished important information on the O defects at anatase particle surfaces and could also clarify the origin of largely Stokes shifted broad photoluminescence band in pristine anatase. New reversible photo-induced spectral change was also found in anatase–AgI composites upon replacing the atmosphere (vacuum ↔ O gas) under 325nm laser light irradiation at room temperature. This spectral change might arise from the excitation energy transfer between excitons in AgI domain and photo-induced O defects at the anatase particle surfaces.

Photoluminescence Study of Defects in Pristine Anatase and Anatase-Based Composites. Mochizuki, S., Shimizu, T., Fujishiro, F.: Physica B, 2003, 340-342, 956-9