Measurement of the full electron spectrum associated with the Ag N3VV Auger transitions: Evidence for the contribution of multi-electron Auger processes

A multi-stop time-of-flight spectrometer for the measurement of positron annihilation-induced electrons in coincidence with the Doppler-shifted annihilation gamma photon

“…Multiple electron emission following the Auger decay of a core hole forms the foundation for explaining the extra intensity found in the inelastic tail of Auger peaks originating from shallow core levels [20][21][22][23][24]. The intensity and energy distribution of the multiple Auger electrons from different samples can provide an estimate of the strength and role of correlation of core holes with valence holes and valence holes with other valence holes in the photon-, electron-or positron-induced electron emission process.…”

“…The coincidence measurement capabilities, when applied to PAES, are expected to be useful in the study of emergent properties on the surfaces of topological insulators [12] or graphene [13] and in the study of new processes involving positron-surface interactions [14][15][16][17][18]. The application of the multi-electron ToF spectrometer to measure the energies of positron annihilation-induced Auger electrons is expected to resolve the contribution of multi-electron Auger decay pathways of the core or deep valence holes which in turn can give critical information on the strength of electron correlation [19][20][21][22][23][24].…”

Positron Annihilation-Induced Auger Electron Spectroscopy Measurements of a TiO2(110) Surface

“…In PAES, positron beam energies well below the electron work function can be used to initiate the Auger process allowing for the complete elimination of the obscuring secondary electron background found in other similar techniques [2]. Experimental determination of the background-free, spectra of electrons emitted as a result of Auger transitions, down to 0 eV, is important for unravelling the complex, correlated Auger decay pathways of core and deep valence holes [3][4][5][6][7]. PAES studies of TiO 2 (110) can also provide important insights relevant to the understanding of positron-stimulated desorption of O + from TiO 2 (110).…”