Total cross sections for single-electron capture from He by keV ${\mathrm{O}}^{+}$ ${}_{}{}^2{}_{}{}^{}$D° and ${}_{}{}^2{}_{}{}^{}$P° metastable ions turned out to be much smaller than for ${\mathrm{O}}^{+}$ ${}_{}{}^4{}_{}{}^{}$S° ground state ions, despite a larger energy defect for the latter reaction. We suggest that this unexpected behavior is caused by efficient suppression of electron capture into either metastable ion due to a competing, collisionally induced inelastic transition into the companion metastable state.

• Received 21 November 1991

DOI:https://doi.org/10.1103/PhysRevA.45.R4218