1 research outputs found
Non-Band-Gap Photoexcitation of Hydroxylated TiO<sub>2</sub>
The photochemistry of TiO<sub>2</sub> has been studied intensively
since it was discovered that TiO<sub>2</sub> can act as a photocatalyst.
Nevertheless, it has proven difficult to establish the detailed charge-transfer
processes involved, partly because the excited states involved are
difficult to study. Here we present evidence of the existence of hydroxyl-induced
excited states in the conduction band region. Using two-photon photoemission,
we show that stepwise photoexcitation from filled band gap states
lying 0.8 eV below the Fermi level of rutile TiO<sub>2</sub>(110)
excites hydroxyl-induced states 2.73 eV above the Fermi level that
has an onset energy of ∼3.1 eV. The onset is shifted to lower
energy by the coadsorption of molecular water, which suggests a means
of tuning the energy of the excited state