Dominant hydrogen complex in natural anatase TiO2.

A study combining vibrational spectroscopy and first-principles theory is presented for a hydrogen-related defect in natural anatase TiO 2 that is characterized by an O–H vibrational mode at 3373 cm − 1 (10 K). Based on complementary Raman scattering, IR absorption, electron paramagnetic resonance, and secondary ion mass spectrometry data supported also by ab initio calculations, it is tentatively proposed that the defect responsible for the 3373 cm − 1 line includes two hydroxyl units located next to a substitutional iron atom, Fe Ti H 2. The defect may exist in at least two charge states, whereby the 3373 cm − 1 line is associated with the positive charge state of the complex. [ABSTRACT FROM AUTHOR]