Auger electron emission in the interaction of slow Na+ ions with Al surfaces

We present energy distributions of electrons emitted in the interaction of Na+ ions with Al surfaces as a function of incident ion energy in the range 300-2000 eV. We discuss the Auger spectra of Sodium, which show several lines due to decay in vacuum of projectiles, singly and doubly excited in the 2p shell by electron promotion in close encounters with target atoms. Our results indicate that the double vacancy production is in close relation with the Al-2p electron excitation via an autoexcitation mechanism.