Kinetic-energy-assisted He⁺-ion neutralization at a solid CO₂ surface

The neutralization of He⁺ ions at a solid CO₂ surface is investigated by analyzing the energy distribution of electrons ejected from the surface and by use of spin-labeling techniques, specifically the use of electron-spin-polarized He⁺ ions coupled with energy-resolved measurements of the ejected-electron polarization. The data indicate that ion impact leads to efficient electron ejection through formation of an autoionizing collision complex comprised of the incident ion and two neighboring CO₂ molecules in which a significant portion of the initial kinetic energy of the ion is converted to potential energy.