AVS 47th International Symposium
    Surface Science Tuesday Sessions
       Session SS2-TuA

Paper SS2-TuA2
Electron-Stimulated Oxidation of Al(111)

Tuesday, October 3, 2000, 2:20 pm, Room 209

Session: Stimulated Processes and Excitations
Presenter: V. Zhukov, University of Pittsburgh
Authors: V. Zhukov, University of Pittsburgh
I. Popova, University of Pittsburgh
J.T. Yates, Jr., University of Pittsburgh
Correspondent: Click to Email
The electron stimulated dissociative adsorption of O@sub 2@ on Al(111) has been studied at surface temperatures from 90 to 300 K. A rastering electron beam technique has been used to deliver electrons with energies from ~1 to 200 eV to the aluminum surface during O@sub 2@ exposure. Experimental evidence for the presence of an O@sub 2@ precursor was found for the oxidized Al(111) surface at low temperature. Precursor adsorption energy of 70-80 meV was estimated from the temperature variation of the oxide growth rate, stimulated by 100 eV electrons. The effect was found to be proportional to the primary beam current. A threshold electron energy of 7 ± 0.5 eV for the electron stimulated oxidation was observed when utilizing electrons with variable energies. This threshold value is in agreement with the 6.8 eV electron attachment cross-section resonance for the gaseous O@sub 2@ species. In contrast to the significant increase of oxidation rate on the oxide-precovered aluminum surface, no effect of electrons was found on the initial stages of oxide growth on the clean Al(111) surface over the temperature range studied. This suggests that the O@sub 2@ precursor is stabilized on oxide clusters.