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. (c) 2007 Published by Elsevier B.V.