Oxygen sticking coefficient and sputtering yields at an Al(1 1 1) surface by ion bombardment

The intensities of light emission from the excitation of sputtered particles under the Ar+ ion bombardment of a single crystal Al(1 1 1) target are measured as a function of the partial oxygen pressure, wavelength and beam energy. The photon yields for two Al I lines (309.2 and 396.2 nm) are found to be proportional to the partial pressure up to ∼10×10−6 Torr. Above that, the photon yields start to decrease, as also observed in other measurements. From the pressure and time dependence of the Al I spectral lines, the sputtering yield, S0, and sticking coefficient, cs, of adsorbed oxygen gas on the Al surface are determined directly. For the three argon ion beam energies 10, 15, and 20 kV, the sputtering yields of oxygen atoms from the surface are 0.45, 0.31, and 0.20 respectively. The sticking coefficient of oxygen atoms on the Al surface is estimated as (5.1±0.8)×10−3.