Electron-capture collisions at keV energies of boron and other multiply charged ions with atoms and molecules. I. Ar,H2, and He

Single-electron-capture cross sections have been measured for boron ions ${\mathrm{B}}^{q+}$ with initial charges $q=2, 3, \mathrm{and} 4$ incident on helium, molecular hydrogen, and argon gas targets. The cross sections show little dependence on the incident ion energy for the range studied, $6q-23q$ keV. Also reported are double-electron-capture cross sections for ${\mathrm{B}}^{3+}$ incident on ${\mathrm{H}}_2$ and Ar and for ${\mathrm{B}}^{4+}$ incident on He, ${\mathrm{H}}_2$, and Ar, as well as a survey of single-electron-capture cross sections for ions of carbon ($2\le q\le 4$), nitrogen ($2\le q\le 5$), and oxygen $2\le q\le 6$) at the single energies $8q$ keV incident on He and Ar targets. In general, it is found that the cross sections do not vary monotonically with the initial charge state, for a fixed colliding atomic species. Each reaction depends in detail on the level structures of both the incident ion and the target atom or molecule.