Infrared Absorption Study of a Dihydrogen Complex in Anatase TiO2

An infrared absorption study of natural anatase TiO2 is performed. A complex with absorption lines at 3355.9 and 3357.3 cm(-1) is shown to consist of at least two equivalent hydrogen atoms, whereby these features are due to the stretch local vibrational modes of two O-H bonds located in the basal plane of the anatase crystal, forming an angle of approximately 90 degrees. The complex is shown to be electrically active with a level in the upper part of the bandgap. The microscopic model of the defect is discussed.