However, our specimens are composed of mixed anatase-to-rutile wt% ratios (cf Table ). To them, the direct Eg transition model would suit better . Given this scenario, the apparent optical direct Eg of specimens thermally treated at 250 °C / 8h does not significanty vary with the irradiation time. On the other hand, the apparent direct Eg of specimens thermally treated at 450 °C / 2h experienced a red-shift upon visible-light irradiation, as listed in Tables 1, and Table , enabling visible-light absorption. [This does not necessarily correspond to an actual rigid narrowing of TiO2's Eg, but it might be the consequence of some electronic transitions deriving from intra-gap localised levels.]