Auger electron-ion coincidence study for H2O adsorbed on SiO2/Si(111) at 80 K

Electron stimulated ion desorption induced by core level excitations has been studied for H2O condensed on a SiO2/Si(111) surface at 80 K [H2O/SiO2/Si(111)] by using Auger electron-ion coincidence spectroscopy. The coincidence H+ yield from the H2O/SiO2/Si(111) was found to be enhanced al the electron kinetic energies corresponding to O(KVV) Auger transitions. This result presents direct and clear evidence of an Auger stimulated ion desorption mechanism accompanied by the cleavage of a covalent bond. A KVNBVNB Auger process is concluded to lead to ion desorption less efficiently than KVBVNB and KVBVB processes (V-NB and V-B represent the non-bonding and bonding valence orbitals, respectively).