Lo phonon-plasmon coupling in non-stoichiometric rutile TiO2

The analysis of the infrared reflectivity spectrum of partially reduced rutile TiO_1.96 reveals a plasmon-LO phonon coupling. Pure-phonon and plasmon frequencies and life times are determined by fit with an appropriate model using the factorized form of the dielectric function for the phonon modes added to a plasmon contribution also derived from the factorized form. Results are compared with data obtained in the insulating stoichiometric rutile.