“…This can be attributed to the fact that the He + ions are formed with thermal energies leading to a very small component of ion energy perpendicular to the surface. (No similar low-energy feature was observed at an argon film [10].) The majority of the incident atoms, however, are deexcited by Auger deexcitation, also referred to as surface Penning ionization, which results in the production of highly-polarized (P e $ 1) electrons with energies in the range 7-10 eV.…”