Total Cross Sections For Electron-impact Ionization Research Articles

Low-Energy Inelastic Collisions of Multiply Charged Ions with Electrons and Hydrogen Atoms

This paper reports the status of current studies, primarily at ORNL, on low energy inelastic collisions of multicharged ions. A few specific measurements and theoretical predictions, which are discussed in other publications, are cited to illustrate present levels of understanding. Recent cross section measurements are presented for ionization of multiply charged ions by electron impact, and for electron capture by multiply charged ions from hydrogen atoms at low energies. For the alkali-like transition-series ions, Ti+3, Zr+3, and Hf+3, the excitation of an inner-shell electron, followed by autoionization (excitation-autoionization) dominates the total electron-impact ionization cross-section by more than an order of magnitude. For electron capture, the total cross-sections for C+q + H and O+q + H collisions (3 ⩽ q ⩽ 6) have been measured at energies ranging from 10-700 eV amu-1. For these few-electron systems at low energies, the capture cross-sections do not scale with ionic charge, or vary uniformly with velocity. Where detailed theory is available, agreement is generally satisfactory.