Enhanced surface sensitivity in AES relative to XPS observed in free argon clusters

The surface-to-bulk intensity ratio in Auger electron spectra has been studied in comparison with core-level photoelectron spectra using free argon clusters of sizes ranging over two orders of magnitude. Enhanced surface sensitivity is observed in L2,3M2,3M2,3 Auger electron spectra compared to 2p photoelectron spectra where electrons of similar kinetic energies were recorded. This is discussed in terms of the effective attenuation length of the electrons.