Kinetic electron emission from Al surfaces by slow ions

Abstract

We measured energy distributions of electrons emitted in the interaction of ${\mathrm{Na}}^{+}$ with Al surfaces at incident ion energies in the range $150--4000\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. The data allow to correlate emission intensities with spectral signatures of electron excitation processes. We find a remarkable contribution to electron emission from asymmetric collisions between incoming ions that have survived neutralization at the surface and target atoms, leading to $\mathrm{Al}\text{\ensuremath{-}}2p$ excitation via a vacancy transfer process. We observe that the total electron emission yields sharp increases by more than an order of magnitude at impact energies above the threshold for this process.