PAES positron annihilation auger electron

PAES (positron annihilation Auger electron spectroscopy) is another technique for producing true AES peak shapes that are free of the secondary electron background. PAES is identical to conventional Auger electron spectroscopy except that the sample excitation is done with a low energy beam of positrons rather than a higher energy beam of electrons. 

Acronyms PAES positron annihilation Auger electron spectroscopy. 

The PAES mechanism, first demonstrated in 1987 [1], can be outlined as follows (1). A positron implanted at low energy diffuses to and gets trapped at the surface. (2). A few percent of the trapped positrons annihilate with core electrons leaving atom in excited state. (3). The atom relaxes via emission of an Auger electron. The PAES mechanism is contrasted with that of electron induced Auger Spectroscopy (EAES) in Figurel2.1. 

The enhanced surface selectivity of PAES stems from the fact that positrons implanted into a metal or semiconductor at low energies have a high probability of diffusing to the surface and becoming trapped in an image-correlation well before they annihilate [3, 9]. The positrons in this well are localized at the surface and annihilate almost exclusively with atoms at the surface. As a result almost all of the Auger electrons originate from the... 

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