Kinetic electron emission from Al surfaces by slow ions

We measured energy distributions of electrons emitted in the interaction of Na + with Al surfaces at incident ion energies in the range 150– 4000 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 Al-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.

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