Auger spectra of Mg, Al, and Si excited by low−energy electron and argon−ion bombardment have been measured and compared. The Auger spectra obtained under ion bombardment are interpreted as a combination of Auger production in excited sputtered species and bulk atoms. Under argon−ion bombardment at these low energies, L2,3 level ionization occurs in the target through an electron promotion mechanism. No L1 level ionization occurs (to first order), and the cross section for double L2,3 level ionization is also small at these ion energies, so no Auger transitions originating from such states result.