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Jellium model is well known and used to understand the neutralization of alkali-metal ions on metal surfacesbut we find it cannot explain our experiments for the neutralization of 0.4 keV and 0.8 keV Na+ ions on Al(1 1 1) and Cu(1 1 0) surfaces in grazing incidence. As the exit angle increases neutral fractions on Cu(1 1 0) surface decreases first and then increases which is similar to our previous results at large scattering angles. While for the Al(1 1 1) surface we observe opposite characteristics. This anomalous bell-shaped feature cannot be explained by the Jellium model. One possible explanation is the inner 2p electron promotion at smaller exit angles this may cause the Na* excited states to be generated and produce excess Na+ ions while the similar electronic excitation process is inefficient for the Cu(1 1 0) surface in the present energy range. [ABSTRACT FROM AUTHOR]

[Display omitted] • For both surfaces, the neutral fractions decrease as the incident energy increases. • Neutral fraction on H 2 O/Cu(1 1 0) is lower than that of Cu(1 1 0). • The work function of H 2 O/Cu(1 1 0) is lightly greater than that of clean Cu(1 1 0). keV-energy Na+ ions are scattered from clean and water covered Cu(1 1 0) surfaces in grazing incidence. For both surfaces the pronounced Na° fractions decrease with incident energy. In particular, the lower Na° fraction has been observed for the water covered Cu(1 1 0) surface. The simple calculations using rate equation are presented to compare with the experimental data. The calculation is in agreement with the experimental data. It indicates that the water covered Cu(1 1 0) surface has the slightly higher work function due to water molecules dissociation and forming hydroxyl groups, so that the neutral fraction on water covered Cu(1 1 0) is lower than that on the clean surface. [ABSTRACT FROM AUTHOR]