THE CHEMISORPTION OF WATER ONTO NI(100) AND PD(110) - A HREELS STUDY

The adsorption of H2O and D2O on Ni(100) and Pd(110) has been studied using high resolution electron energy loss spectroscopy (HREELS). A series of spectra were measured as a function of coverage, and each series was fit to a set of Gaussian functions to determine the individual loss features contributing to the spectra. By examining the effects of water coverage and the metal surface on these loss features, details about the geometry and bonding of the adsorbed water can be obtained. The analysis indicated that the Pd-OH2 bond is substantially weaker than the Ni-OH2 bond. This difference, along with the structural difference between the (110) and (100) surfaces, greatly influences the adsorption process. The Pd(110) data are consistent with the formation of a bilayer structure on the surface, while the Ni(100) data indicate a more disordered arrangement. These results are also discussed in relation to the rather broad base of work done on the adsorption of water on various single crystal metal surfaces.