RESONANTLIKE DESORPTION OF NEGATIVE-IONS BY CORE-LEVEL EXCITATION UNDER ELECTRON-BOMBARDMENT

Electron-stimulated desorption of positive and negative hydrogen ions from hydrogenated GaAs surfaces has been studied as a function of impa ct electron energy. Well-defined peaks in the negative ion yield are o bserved at incident electron energies close to Ga and As core-level bi nding energies, suggesting that resonantlike core-level electronic tra nsitions involving matrix atoms are most likely responsible for such b ehavior. We propose that the formation and subsequent breakup of super excited molecular complexes containing a core hole can lead directly t o the ejection of negative ions.