The role of Coster-Kronig transitions in the ionization of surface atoms

Since Coster-Kronig transitions for isolated atoms are often characterized by higher transition rates than other types of Auger emission, it is important to consider the quantitative effect of these transitions on the Auger electron spectroscopy of solid surfaces. We find that cross sections for the electron impact ionization of L and M shells of surface atoms are augmented by core electron vacancy production due to Coster-Kronig transitions. In the case of L2,3 shell ionization of adsorbed Cl, and L1 contribution is calculated to be about 17% of the total cross section for incident electron energies which exceed four times the L2,3 ionization energy. The M1 and M2,3 ionizations account for about 25% of the total M4,5 ionization cross section for Ba when the energies of the incident electrons exceed the subshell ionization thresholds. Calculated cross sections exhibit good agreement with experimental values for the above elements when the effects of Coster-Kronig transitions are included. It is also shown...