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The aim of the present work was to study D218O reactivity at room temperature with (100) surfaces of MgO single crystals doped with either Ni or Co by Electron Stimulated Desorption (ESD) in the 5-1000 eV range. The reactivity was studied on both as-grown and after thermochemical reduction (TCR) samples. It was observed that Ni2+ and Co2+ metallic ions are present in the surface as substitutional ions and, that during TCR, precipitates and oxygen vacancies are formed, influencing water adsorption. The Ni and Co impurities also have a strong influence on the diffusion parameters of the dissociated H and D atoms. The growth of the D218O layer was studied by recording the intensities of the ESD O+, OD+, and D+ desorbed ions. The influence of the electron bombardment on the adsorption was also analyzed and the total cross-section (e.g. ions plus neutrals) for the ESD detected ions was determined. Charging effects at the surface due to incident electrons were taken into account in the determination of the absolute values of desorbed ion kinetic energies. A detailed analysis of the kinetic energy distribution of the 16O+ and 18O+ ions was performed. The O+ ion distribution exhibits the usual bimodal structure for both doped and undoped MgO surfaces, which is associated with the presence of two O surface sites. One of the O sites corresponds to the stoichiometric oxygen from the MgO lattice, and the other to defect regions and/or oxygen from the dissociated D218O . This bimodal structure is strongly affected by the energy of the incident electrons as well as by the amount of the adsorbed species. The minimum electron energy to desorb ions, i.e. the threshold energy, is determined for the O+, OD+, and D+ desorbed ions. These thresholds are related with the specific local bond of the neutrals with the surface atoms, and are discussed on the basis of the Feibelmann-Knotek mechanism as well as the secondary electron yield. |