title: Control of a surface photochemical process by fractal electron transport across the surface: O(2) photodesorption from TiO(2)(110).
abstract: The photodesorption of O(2) from TiO(2)(110) has been found to exhibit fractal kinetic behavior. The rate coefficient for photodesorption is measured throughout the entire experiment and is shown to decrease by a factor of approximately 100 over a time period of approximately 250 s. A model is proposed in which the electrons associated with O-vacancy defects on the surface percolate from vacancy site to vacancy site via the filled orbitals at these sites to neutralize photoproduced holes. This electron percolation, causing electron-hole recombination, reduces the efficiency of charge transfer between a photoproduced hole and an O(2)(-)(a) species localized at a vacancy defect site, causing the rate of O(2) photodesorption to follow a fractal rate law. We postulate that the fractal electron conduction path across the surface is one-dimensional.
authors.affiliation: Surface Science Center, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: Tracy L
authors.initials: TL
authors.lastname: Thompson
authors.forename: John T
authors.initials: JT
authors.lastname: Yates