Electronic Resource
College Park, Md.
:
American Institute of Physics (AIP)
The Journal of Chemical Physics
102 (1995), S. 4657-4662
ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
We have investigated the adsorption and thermal conversion of molecular oxygen (O2) states on the TiO2(110) surface by making use of the distinct photodesorption behavior of each adsorption state. Oxygen chemisorbs at the oxygen vacancy defect sites on the annealed TiO2(110) surface at 105 K to a saturation coverage of less than 0.12 monolayers (ML), producing mostly the α-O2 species which is observed to undergo slow photodesorption. Upon heating this surface to above 250 K, the α-O2 is converted to the β-O2 state which can photodesorb at a significantly higher rate. The β-O2 species dissociates above 400 K to produce atomic oxygen, eliminating the oxygen anionic vacancies. Both the α- and β-photodesorption processes have a threshold energy at the TiO2 band gap (3.1 eV), indicating a substrate excitation mediated process. The photodesorption time-profile is fitted with an exponential decay function with a cross section of ∼8×10−17 cm2 for the α-O2 and ∼1.5×10−15 cm2 for the β-O2 species at a photon energy of 3.94 eV. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.469513
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