MULTIPLY CHARGED IONS FROM ELECTRON-BOMBARDMENT OF SIO2

We present the first systematic measurements of the emission of multiply charged substrate Si ions from SiO2 under electron bombardment. The electron energy dependences of the ion yields show structure related to the Si 2p and O 1s thresholds, but delayed in energy. The ion yields do not follow core-ionization cross sections. The energy distributions of Si ions are a few eV wide, while those of O+ extend to >25 eV. The results are consistent with a mechanism involving Auger decay from a core hole in the presence of additional electronic excitations. © 1990 The American Physical Society.