Sensitivity of positron-annihilation-induced Auger-electron spectroscopy to the top surface layer

Abstract
We present the first study of positron-annihilation-induced Auger-electron emission from a well defined overlayer-metal system. A 0.5 monolayer of S on Cu(110) produced a fourfold reduction in the positron induced Cu M2,3VV Auger peak. The attenuation is accounted for by theoretical calculations indicating that the positron surface state is displaced away from the Cu surface by the S overlayer, decreasing the annihilation rate of positrons with Cu core electrons.