Ion Stimulated Desorption of Secondary Ions from Ionic Compound Surfaces

The mechanism of secondary ions formation has been investigated during He⁺ bombardment of ionic-compound surfaces. The O⁺ ions desorb from the TiO₂(110) surface via the potential emission as revealed from their energy and angular distributions, while very little O⁺ ejection occurs from the MgO(001), Al₂O₃(0001), and SiO₂ surfaces. The O⁺ ion is caused by the antibonding state with the O $2s$ core hole and its decay via the intra-atomic Auger process, resulting from the strong O $2p$--Ti $3d$ hybridization and the quasiresonant charge exchange between the He $1s$ and O $2s$ states.