BACKGROUND-FREE AUGER LINE-SHAPE OF AG N2.3VV MEASURED WITH POSITRON-ANNIHILATION INDUCED AUGER-ELECTRON SPECTROSCOPY

Auger spectra for the Ag(100) N2.3VV transition obtained utilizing pos itron annihilation induced Auger electron spectroscopy (PAES) are pres ented. This low energy transition of Ag is difficult to separate from the large secondary background which is present using electron induced Auger electron spectroscopy (EAES) and has not been studied extensive ly. In our measurements, the secondary electron background is eliminat ed by utilizing a positron beam whose energy is below the energy range of the of the Auger electrons. Measurements of the temperature depend ence of PAES intensity, I-PAES and positronium fraction, f(PS), indica te that I-PAES is proportional to the quantity(I - f(PS)). Electron en ergy spectra taken at high temperature (f(PS) approximate to 1) clearl y demonstrate that the prominent low energy tail (LET) present in the PAES spectra is associated with Auger transitions and is not due to se condary electrons induced by collisions with the primary positron beam . The Auger line shape of the N2.3VV transition of Ag(100) is accounte d for in terms of the convolution of the density of states of the N-2. 3 core levels and the density of states of the correlated two-hole fin al states estimated from the N,, XPS core level spectra and the Auger line shape of the M4VV transition. In addition, possible mechanisms le ading to the production of the LET including a N2N3V transition follow ed by a N3V-VVV transition and/or electron energy loss during the esca pe from the topmost layer are discussed.