Interference Effect in Resonant Double-Charge Transfer

Total cross sections for charge transfer in ${\mathrm{Mg}}^{+}$-Mg and ${\mathrm{Mg}}^{++}$-Mg collisions have been measured in the energy range of 1.2-1000 keV. The cross section for resonant double-charge transfer shows a pronounced structure which can be understood as an effect of phase interference between two resonant charge-transfer channels. This is substantiated quantitatively by a model calculation.