XPS studies for NaCl deposited on the Ni(111) surface

Vapor deposited NaCl on the Ni(111) surface was characterized by XPS. Three types of NaCl were found on the surface. First, the NaCl interacted strongly with Ni giving the Nals peak at 1072.2 eV, the C12p peak at 198.8 eV and the NaKLL peak at 494.3 eV. The 494.3 eV peak shifted to 493.4 eV when measured at ∼ 500 K. The energy of the NaKLL peak and the modified Auger parameter for sodium were nearer to those for Na metal than to those for bulk NaCl. The species was assigned to NaCl which was freed from the potential of the NaCl crystal and which had a weakened NaCl bond. The other types were characterized by using H2O as a probe. One set of the peaks, the Nals peak at 1072.8 eV, the C12p peak at 199.6 eV and the NaKLL peak at 497.7 eV, was assigned to NaCl which was in the form of a very thin crystal. The other set, the Nals peak at 1073.5 eV, the C12p peak at 200.1 eV and the NaKLL peak at 498.5 eV, was obtained during crystal growth of NaCl as large islands upon annealing. The energies suffered from the charging effect. The effect of coadsorbing oxygen was also studied.