Surface effects on energies of Auger electrons from Xe(111)

The XeN4,5O2,3O2,3 Auger spectrum of a Xe crystal grown on Pd(111) is found to consist of two atomiclike subspectra from surface and bulk Xe atoms, respectively, separated by ΔA=0.79±0.05 eV. This surface Auger-electron shift is three times as large as the simultaneously studied surface shift of the Xe $4d$ core-level photoemisson lines. We explain these surface shifts in terms of a reduced dielectric screening of the positive hole states in surface atoms as compared with the bulk.