The Auger Parameter of Adsorbed Xenon as a Probe of Surface Polarizability

The change in Auger parameter, α (α = Auger kinetic energy minus photoelectron kinetic energy from core levels) between gas phase and adsorbed phase xenon provides an unambiguous measure of final state electronic relaxation in the surface toward the xenon ion. For many surfaces this relaxation is purely electronic polarization in the surface so that the Auger parameter provides a measure of the surface polarizability. Moreover, the Auger parameter for adsorbed xenon can be related to the relaxation energy in core level photoemission with high accuracy. Measurement of the xenon Auger parameter and its sensitivity to surface dielectric properties is illustrated by experiments on a series of oxygen treated Mo(100) surfaces.