Electron-capture collisions at keV energies of multiply charged ions of carbon and argon with molecular deuterium

Single- and double-electron-capture cross sections have been measured for ${\mathrm{C}}^{q+}$ with initial charges $2\le q\le 6$ and for ${\mathrm{Ar}}^{q+}$ with initial charges $2\le q\le 12$ incident on molecular deuterium gas targets. The cross sections show little dependence on the incident-ion energy for the range studied $2q-10q$ keV. The single-electron-capture cross sections do not vary monotonically with the initial charge, but show an oscillation about a mean curve, reflecting the projectile electronic structure.