Energy Spectra of ion-induced Auger electrons under channeling conditions

We have measured the secondary-electron energy spectra resulting from 3.0- and 3.5-MeV ${\mathrm{H}}^{+}$ bombardment of a single-crystal silicon target under Si channeling and nonchanneling conditions. The energy degradation of Si $K$-shell Auger electrons observed in the secondary-electron spectra has been successfully interpreted by a theoretical model based on the ion-beam shadowing effect and on the Poisson distribution of the inelastic scattering suffered by the electrons. The relationship between the mean free path for inelastic scattering and the mean energy of excitations produced by 1.6-keV electrons in the Si crystal was obtained from a comparison between the measured and calculated energy spectra of the energy-degraded Si $K$-shell Auger electrons. This relationship gives a mean excitation energy of 44.2± 3.5 eV when the mean free path for inelastic scattering is assumed to be $\lambda =32\mathrm{}$ Å, as given by theory.