Electron binding energies of core levels in caesium adsorbed on a nickel (100) surface

Electron binding energies obtained from X-ray photoemission and workfunctions obtained from UV photoemission have been recorded for caesium adsorbed on nickel (100) at coverages from 0.1 to >1.0 monolayer. Analysis of coverage as a function of Cs⁺ dose suggests a sticking coefficient of 0.5 for Cs⁺ on nickel (100) in submonolayer range and 0.05 above a monolayer of deposited caesium. The binding energy of the caesium 3d_5/2 level, referred to the Fermi energy of the adsorption system, is 726.0+or-0.2 eV, independent of coverage. Comparison of binding energies of atomic caesium and caesium adsorbed at saturation coverage shows that the total change in electron binding energy, Delta E_B, depends on the core levels studied (5s to 3s); subtracting a modified relaxation energy yields a solid state shift in binding energy of 2-4 eV.