Abstract
We studied absorption and emission transitions in the visible range through three distinct electronic midgap states in nanocrystalline rutile TiO2 using absorption spectroscopy, “conventional” photoluminescence (PL) spectroscopy, synchronous luminescence spectroscopy for the first time, and complementary methods. We have used free exciton in rutile as an intrinsic midgap state (obtained under the subbandgap photoexcitation at 430 nm) to assign luminescence bands of “green light” (ca. 520 nm) and “green–yellow light” (ca. 560 nm) at 25 °C. Further, we utilized water in the vapor phase as spectroscopic probe to learn about origin of visible emission in rutile. Visible photoluminescence is increased by factor ×20 after water desorption and reversibly decreased (quenched) upon water adsorption in air under ambient conditions. Preferential quenching of “green–yellow light” by adsorbed water occurs versus “green light” as originating from surface vs subsurface oxygen vacancies. Water “adsorption/desorption” was...
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
