Auger-Electron Emission Resulting from the Annihilation of Core Electrons with Low-Energy Positrons

We report the first demonstration of positron-induced Auger-electron spectroscopy. A beam of low-energy (10¹ eV) positrons was used to create core holes at the surface of Ni and Cu by matterantimatter annihilation. Estimates are developed for the probability of positrons annihilating with a $3p$ electron found to be as high as 3.7(7)×{}10^-2 in Ni. The implications of the extremely high signal to background are discussed and several important advantages of this process for surface analysis are suggested.