Excitation Resonances for the Production of Metastable Atoms in Low-Energy Argon Ion-Atom Collisions

Metastable argon atoms are found to be forward scattered along with ground-state atoms after ${\mathrm{Ar}}^{+}$ + Ar charge-transferring collisions. Using a detection technique involving Penning ionization of acetylene, it was found that the cross section for metastable excitation has a magnitude of the order of ${10}^{-3\mathrm{}}$ ${\mathrm{\AA }}^2$ and exhibits two distinct low-energy resonances as a function of incident ${\mathrm{Ar}}^{+}$ energy.