Molecular and chemical effects in Auger processes induced by molecular ions

The $\mathrm{Al}{L}_{2,3}\mathrm{VV}$ Auger electrons ejected under ${\mathrm{H}}^{+}$ and ${\mathrm{H}}_2^{+}$ ion bombardments were measured at the backward directions. The observed ratio of the Auger-electron yield per proton for ${\mathrm{H}}_2^{+}$ to that for ${\mathrm{H}}^{+}$ ejected from oxidized aluminum foils increases from 1.0±0.1 to 1.6±0.1 with an increase of the projectile energy from 0.25 to 1.2 MeV/amu, whereas the ratio for oxide-free aluminum foils remains approximately constant (1.1±0.1). First-order perturbation theory fails to reproduce the observed results for both targets.