AVS 46th International Symposium
    Surface Science Division Monday Sessions
       Session SS1+EM-MoM

Paper SS1+EM-MoM9
Photoconversion of Adsorbed Oxygen States On TiO@sub 2@(110)

Monday, October 25, 1999, 11:00 am, Room 606

Session: Chemistry on Oxides
Presenter: C.L. Perkins, Pacific Northwest National Laboratory
Authors: C.L. Perkins, Pacific Northwest National Laboratory
M.A. Henderson, Pacific Northwest National Laboratory
Correspondent: Click to Email
By means of postirradiation temperature programmed desorption we have investigated further the states of oxygen adsorbed on rutile TiO@sub 2@. Previous work has shown that annealing the (110) surface in vacuum produces isolated bridging oxygen vacancies, and that these vacancies are intimately connected with molecular and dissociative oxygen adsorption channels. We find that at 120 K illumination of the oxygen exposed surface with photons having energies above the band gap (>3.6 eV) results in depletion of the molecular oxygen state observed at 410 K in TPD, in contrast to the remaining oxygen destined for the dissociative channel. An unusual effect of water overlayers on the O/TiO@sub 2@(110) system is explored. For thick overlayers (> 2 ML), it is possible to generate via UV irradiation a previously unobserved oxygen TPD state. Cross sections for the photoconversion of oxygen into this state are measured, and specific mechanisms for the process are proposed.