Kinetic-energy-assistedHe+-ion neutralization at a solidCO2surface

The neutralization of ${\mathrm{He}}^{+}$ ions at a solid ${\mathrm{CO}}_{2}$ 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 ${\mathrm{He}}^{+}$ 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 ${\mathrm{CO}}_{2}$ molecules in which a significant portion of the initial kinetic energy of the ion is converted to potential energy.