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Calculated energy loss of swift He, Li, B, and N ions in Si O 2 , Al 2 O <mml:…

2005; American Physical Society; Volume: 72; Issue: 5 Linguagem: Inglês

10.1103/physreva.72.052902

1538-4446

Santiago Heredia‐Avalos, Rafael Garcia‐Molina, José M. Fernández‐Varea, Isabel Abril,

Ion-surface interactions and analysis

We have calculated the electronic stopping power and the energy-loss straggling parameter of swift He, Li, B, and N ions moving through several oxides, namely $\mathrm{Si}{\mathrm{O}}_{2}$, ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$, and $\mathrm{Zr}{\mathrm{O}}_{2}$. The evaluation of these stopping magnitudes was done in the framework of the dielectric formalism. The target properties are described by means of a combination of Mermin-type energy-loss functions that characterize the response of valence-band electrons, together with generalized oscillator strengths to take into account the ionization of inner-shell electrons. We have considered the different charge states that the projectile can have, as a result of electron capture and loss processes, during its motion through the target. The electron density for each charge state was described using the Brandt-Kitagawa statistical model and, for He and Li ions, also hydrogenic orbitals. This procedure provides a realistic representation of both the excitation properties of the target electrons and the projectile charge density, yielding stopping powers that compare reasonably well with available experimental data above a few tens of keV/amu.