Influence of Li impurities on the adsorption of D2O on MgO (100)

The aim of the present work is to elucidate the role played by lithium impurities in the D2O adsorption on MgO(1 0 0) surfaces at room temperature and on H and D diffusion processes by using electron stimulated desorption (ESD). The growth of the D2O layer has been studied by recording the intensity of O+, OD+ and D+ desorbed ions. Whereas for undoped MgO surfaces the O+ intensity decreases with coverage, in Li-doped MgO surfaces the intensity increases. These findings together with the observed threshold energy of D+ desorbed ions at 55 +/- 5 eV indicate that adsorbed D2O undergoes preferentially total dissociation on the MgO: Li system. This threshold energy corresponds to the Mg 2p excitation, which means that the D species are bonded to the Mg atoms. (C) 2002 Elsevier Science Ltd. All rights reserved.