AN AES AND SIMS STUDY OF THE EFFECT OF TEMPERATURE ON THE INTERACTION OF OXYGEN WITH AL(100)

Oxygen in chemisorbed, oxide and mixed chemisorbed/oxide layers deposited on Al(100) at 300 K is shown to be essentially immobile with respect to migration across the surface and with respect to diffusion into the subsurface for temperatures up to ∼ 700 K. The immobility of chemisorbed oxygen prevents it from being thermally converted to the oxide for temperatures up to 700 K. It is argued, in accord with the predictions of ab-initio calculations [K.L. Bedford and A.B. Kunz, Phys. Rev. B 25 (1982) 2119], that the immobility of chemisorbed oxygen on Al(100) is consistent with the adsorption of oxygen within or slightly below the surface Al plane at fourfold hollow sites. Increasing the temperature of the Al(100) surface during oxygen adsorption is shown to enhance subsurface oxidation even though increasing the surface temperature in UHV following oxygen adsorption at 300 K does not cause diffusion of oxygen into the subsurface or enhance oxide formation. © 1990.