n-Type doping of TiO2 with atomic hydrogen-observation of the production of conduction band electrons by infrared spectroscopy

Irradiation of powdered TiO2 by atomic hydrogen has been shown to produce electron–hole pairs in the TiO2. The electronic excitation from shallow traps is measured in the IR region by absorption spectroscopy, where IR photons excite H-atom derived electrons into the conduction band continuum. The activation energy for atomic H diffusion into the TiO2 crystal lattice is low: 0.09 ± 0.01 eV. D atom substitution for H does not influence the kinetics of production of shallow-trap electrons nor of their decay.