Coadsorption of Cesium and Oxygen on Ni(100). I. Cesium Probing of Ni-O Bonding.

摘要

Low energy electron diffraction (LEED) and work function measurements have been used to study the interaction of Cs and O on (100) surfaces of Ni. Deposition of Cs on oxygen-chemisorbed Ni(100) changed the structure of the O array. The work function of this surface showed a minimum at 0.14 monolayer of Cs coverage and a maximum at 0.29 monolayer. On the other hand, Cs on oxidized Ni(100) could not change the oxygen arrangement at all, and the work function remained constant after reaching a minimum value. These two types of behavior of Cs can be used to probe the bonding states of O on metal surfaces. Our results suggest that the c(2X2) structure of O on Ni(100) is simple chemisorption rather than receonstruction and that the c(2X2) coexists with regions of disordered NiO on Ni(100). While LEED intensity variations detect primarily the chemisorbed c(2x2), other measurements like work function, ion neutralization and sticking coefficient should detect both kinds of Ni-O bonding. (Author)