Theoretical investigation of charge transfer in collisions of ${\mathrm{C}}^{6+}$ and ${\mathrm{N}}^{7+}$ ions with H and ${\mathrm{H}}_2$ targets at low to intermediate energy

Recent measurements by Meyer et al. [Phys. Rev. A 32, 3310 (1985)] have revealed that the charge-transfer cross section for ${\mathrm{N}}^{7+}$ +H collisions is much larger than that for ${\mathrm{N}}^{7+}$ +${\mathrm{H}}_2$ collisions below 3 keV/amu, whereas the opposite trend is seen in the measured charge-transfer cross sections for ${\mathrm{C}}^{6+}$ on H and ${\mathrm{H}}_2$ targets. These anomalous experimental findings have been investigated for the first time theoretically, using the traveling-molecular-orbital expansion approach, in the energy range from 0.14 to 9 keV/amu. Our qualitative argument based on adiabatic potentials and corresponding couplings as well as a five-state close-coupling calculation provides support for experimental findings.