Transmission of Low Energy (<10 eV)O+Ions through Several Monolayer Thick Rare Gas Films

We present the first systematic study of the transmission of low energy oxygen ions (<10 eV) through ultrathin films of Ar, Kr, and Xe. For rare gas films adsorbed on an oxidized W(100) surface, we find that a small fraction of ${\mathrm{O}}^{+}$ can penetrate more than 5 ML thick films of Kr and Xe. The attenuation of ${\mathrm{O}}^{+}$ is strongest for Ar overlayers. We attribute the attenuation mainly to elastic scattering of the ions with the rare gas atoms. We suggest that structural characteristics of rare gas films adsorbed on this surface are the cause for low attenuation in the first 1-2 monolayers.