Direct evidence for low-energy electron emission following O LVV Auger transitions at oxide surfaces

Abstract

Oxygen, the third most abundant element in the universe, plays a key role in the chemistry of condensed matter and biological systems. Here, we report evidence for a hitherto unexplored Auger transition in oxides, where a valence band electron fills a vacancy in the 2s state of oxygen, transferring sufficient energy to allow electron emission. We used a beam of positrons with kinetic energies of $$\sim 1$$ ∼ 1 eV to create O 2s holes via matter-antimatter annihilation. This made possible the elimination of the large secondary electron background that has precluded definitive measurements of the low-energy electrons emitted through this process. Our experiments indicate that low-energy electron emission following the Auger decay of O 2s holes from adsorbed oxygen and oxide surfaces are very efficient. Specifically, our results indicate that the low energy electron emission following the Auger decay of O 2s hole is nearly as efficient as electron emission following the relaxation of O 1s holes in $$\hbox {TiO}_2$$ TiO 2 . This has important implications for the understanding of Auger-stimulated ion desorption, Coulombic decay, photodynamic cancer therapies, and may yield important insights into the radiation-induced reactive sites for corrosion and catalysis.

Plasmon Excitation in the Interaction of Slow Singly Charged Argon Ions with Magnesium

“…The knowledge of these phenomena is not readily accessible through scattering techniques and charge fraction measurements. On the other side, electron emission is one of the main outcomes of these processes, making electron spectroscopy techniques very well-suited to obtain detailed information on electronic processes that occur in ion-solid interaction [13][14][15][16], which can complements the information obtained with other techniques.…”