Electron impact desorption of ions from gas-covered Si(111) surfaces

The electron impact desorption of ions was investigated using approx.100-eV electrons from Si(111) surfaces covered with O2, H2O, CO, NO, HC1, H2S, and NH3. The observed ions are O+ from Si-O2 and Si-NO; H+ and O+ from Si-H2O; and Cl+ from Si-HCl. The ion yields, energy distributions of ions, and electron energy dependence of relative ion yields are reported. It is found that O2, H2O, and NO adsorb in a single state, respectively, and HCl adsorbs in at least two states