AUGER LINE-SHAPE MEASUREMENTS USING POSITRON-ANNIHILATION INDUCED AUGER-ELECTRON SPECTROSCOPY

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 la rge secondary electron background in the Auger peak region. In positro n annihilation induced Auger electron spectroscopy (PAES), the core ho les are created by matter-antimatter annihilation and not through coll isional ionization. Measurements are reviewed which indicate that PAES can eliminate the secondary electron background by the use of very lo w (approximately 10 eV) positron beam energies and that PAES has great ly increased surface selectivity due to the trapping of positrons in s urface state prior to annihilation. A new PAES spectrometer has been d eveloped in our laboratory with an energy resolution which is an order of magnitude better than previous PAES spectrometers. The high-resolu tion PAES system has been used to measure the Auger M2,3VV line shape from a clean polycrystalline Cu surface. The atomic-like Auger M2VV an d M3VV features are clearly resolved. Differences observed between the PAES spectra and spectra obtained using electron induced Auger spectr oscopy are discussed.