Auger line shape measurements using positron annihilation induced Auger electron spectroscopy

Abstract

Conventional methods of Auger electron spectroscopy (AES) make use of energetic electron or photon beams to create the core-hole excitations that lead to the Auger transition. The energetic beams result in a large secondary electron background in the Auger peak region. In positron annihilation induced Auger electron spectroscopy (PAES), the core holes are created by matter-antimatter annihilation and not through collisional ionization. Measurements are reviewed which indicate that PAES can eliminate the secondary electron background by the use of very low (∼10 eV) positron beam energies and that PAES has greatly increased surface selectivity due to the trapping of positrons in surface state prior to annihilation. A new PAES spectrometer has been developed in our laboratory with an energy resolution which is an order of magnitude better than previous PAES spectrometers. The high-resolution PAES system has been used to measure the Auger M 2,3 VV line shape from a clean polycrystalline Cu surface. The atomic-like Auger M 2 VV and M 3 VV features are clearly resolved. Differences observed between the PAES spectra and spectra obtained using electron induced Auger spectroscopy are discussed.