Desorption Cross Section of an Adsorbed Oxygen Atom on an Al Surface by Ar⁺ Bombardment

Abstract

The intensity of light emission from excited Al atoms sputtered from a metal surface strongly depends on the degree of oxygen coverage θ of the target surface. Desorption cross section of an adsorbed oxygen atom by Ar⁺ bombardment was obtained for a polycrystalline Al surface by means of a time transient spectroscopic technique. The results obtained is (3.7± 0.2)× 10^-16 cm² for the Al polycrystalline target at the projectile energy of 40 keV. The initial sticking probability s₀ of an adsorbing oxygen atom was estimated and the value obtained agreed to the reported values within experimental errors. A very sharp spike in intensity was found to appear for the resonance line of Al atom sputtered from the Al surface in a transient experiment when the oxygen coverage becomes large (θ ∼ 1) in addition to a decay curve usually observed with a large time constant.