Electron removal from atomic hydrogen by collisions with fully stripped carbon

Total cross sections for charge transfer and impact ionization in ${\mathrm{C}}^{+6\mathrm{}}$-H collisions have been calculated for the range of relative velocities (0.1-10) × ${10}^8$ cm/sec. At the lower velocities [(0.1-2) × ${10}^8$ cm/sec] coupled-state calculations in an impact-parameter approximation were made of the charge-transfer cross sections using a basis set of exact one-electron two-center wave functions. An investigation of the origin dependence of these perturbed stationary-state calculations showed that differences of about 30% in the cross sections occur when the origin is shifted from the target to the ion center. At the higher velocities a classical-trajectory Monte Carlo approach was employed to determine both the charge-transfer and impact-ionization cross sections. The two sets of calculations are in reasonable agreement in the overlapping energy range, and give a comprehensive picture of the overall electron-removal cross section. They show that electron capture dominates in the region between 0.1 × ${10}^8$ and 3 × ${10}^8$ cm/sec with a peak cross section of ∼ 5 × ${10}^{15}$ ${\mathrm{cm}}^2$ at $v\approx 7\times {10}^7$ cm/sec. The capture is predominantly into the $n=4\mathrm{}$ levels of the product ${\mathrm{C}}^{+5\mathrm{}}$ ion. Impact ionization is found to be the most important electron removal process at velocities above 4 × ${10}^8$ cm/sec.